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WO2011001571A1 - Wavelength-variable laser light source and method for driving same - Google Patents

Wavelength-variable laser light source and method for driving same Download PDF

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Publication number
WO2011001571A1
WO2011001571A1 PCT/JP2010/002043 JP2010002043W WO2011001571A1 WO 2011001571 A1 WO2011001571 A1 WO 2011001571A1 JP 2010002043 W JP2010002043 W JP 2010002043W WO 2011001571 A1 WO2011001571 A1 WO 2011001571A1
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WIPO (PCT)
Prior art keywords
ring
optical
optical waveguide
wavelength
optical amplifier
Prior art date
Application number
PCT/JP2010/002043
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French (fr)
Japanese (ja)
Inventor
石坂政茂
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日本電気株式会社
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Publication date
Priority claimed from JP2009153700A external-priority patent/JP5240095B2/en
Application filed by 日本電気株式会社 filed Critical 日本電気株式会社
Publication of WO2011001571A1 publication Critical patent/WO2011001571A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/14—External cavity lasers
    • H01S5/141—External cavity lasers using a wavelength selective device, e.g. a grating or etalon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/02—Structural details or components not essential to laser action
    • H01S5/022—Mountings; Housings
    • H01S5/023—Mount members, e.g. sub-mount members
    • H01S5/02325—Mechanically integrated components on mount members or optical micro-benches
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/14—External cavity lasers
    • H01S5/141—External cavity lasers using a wavelength selective device, e.g. a grating or etalon
    • H01S5/142—External cavity lasers using a wavelength selective device, e.g. a grating or etalon which comprises an additional resonator

Definitions

  • the present invention relates to a light source used for optical communication, optical information processing, optical interconnection, and the like, and more particularly to a wavelength tunable laser light source having a wavelength tunable function and a driving method thereof.
  • Wavelength division multiplex communication increases the capacity by increasing the number of wavelengths.
  • WDM Wavelength Division Multiplexing
  • expansion of communication capacity with more flexibility is being actively studied, coupled with progress in ROADM (Reconfigurable Optical Add / Drop Multiplexing), optical cross-connect by wavelength routing, and the like.
  • ROADM Reconfigurable Optical Add / Drop Multiplexing
  • wavelength resources are not only used for capacity expansion, but are also actively used for improving network functions.
  • the expansion of the communication capacity and the enhancement of the functions of the communication system enable the provision of a low-cost and highly secure communication service in relation to each other.
  • a tunable laser is one of the key devices important in constructing such a communication system.
  • a plurality of fixed wavelength light sources having a fixed wavelength interval are arranged side by side, and the cost of maintenance management backup light sources (for the number of wavelengths) is particularly large, which hinders cost reduction of the system. It was a factor.
  • the types of the light sources can be integrated into one, so that the reduction of the system cost is greatly advanced.
  • a wavelength tunable light source having a high switching speed is an indispensable element for realizing a new network function even in wavelength routing.
  • Non-Patent Document 1 As a wavelength tunable light source that can cover the C (Conventional) band or the L (Long) band, a movable MEMS mirror (Micro Electro Mechanical Systems Mirror) is used.
  • Non-Patent Document 1 is published by Berger et al. Although the wavelength tunable light source of Non-Patent Document 1 shows relatively good light output characteristics, there are concerns about its practicality in terms of manufacturing cost and impact resistance. Further, the mode stability of a DBR (distributed reflection type) laser is improved and further integrated with a modulator. Although reported in Non-Patent Document 2 by Mason et al., There are problems in terms of cost reduction and reliability.
  • DBR distributed reflection type
  • a tunable light source using a planar optical circuit (PLC) as an external resonator is relatively easy to manufacture and does not have a movable part like MEMS. Therefore, it is excellent in terms of production yield and reliability (particularly vibration resistance) and is considered suitable for mass production, and several configurations have been proposed at present.
  • PLC planar optical circuit
  • the wavelength tunable range is determined by the wavelength tunable range of the ring-type external resonator and the gain band of the semiconductor amplifier. For this reason, there is a structural limitation in performing wavelength tuning over a wide range with high output.
  • DWDM wavelength division multiplex transmission system
  • a communication wavelength band is mainly divided into a C band and an L band, and a large number of wavelength signal lights are assigned to a wavelength range of about 40 nm.
  • many tunable lasers are being developed based on a wavelength range of 40 nm.
  • CWDM Coarse WDM
  • the present invention has been made to solve the above problems, and provides a wavelength tunable laser light source capable of expanding the wavelength tunable range with a relatively simple configuration, and a driving method thereof. For the purpose.
  • a wavelength tunable laser light source includes a first input port, a second input port, and an output port, and a wavelength tunable filter capable of moving a wavelength spectrum peak of transmitted light intensity;
  • a first optical amplifier having one end optically connected to the first input port;
  • a second optical amplifier having one end optically connected to the second input port and having a gain wavelength spectrum different from that of the first optical amplifier;
  • an optical mirror provided on the end face of the output port and having a predetermined reflectance and transmittance.
  • a wavelength tunable laser light source driving method is the above-described wavelength tunable laser light source driving method, wherein the first optical amplifier and the second light are selected according to a desired wavelength. It is characterized in that current is injected into one of the amplifiers and at the same time no current is injected into the other.
  • the present invention it is possible to provide a wavelength tunable laser light source capable of expanding the wavelength tunable range with a relatively simple configuration, and a driving method thereof.
  • FIG. 2 is a schematic diagram showing a schematic configuration of a wavelength tunable laser light source according to Embodiment 1.
  • FIG. 3 is a schematic diagram illustrating a state of a resonance path of a light wave when one optical amplifier is driven in the wavelength tunable laser light source according to the first embodiment.
  • FIG. 3 is a schematic diagram illustrating a state of a resonance path of a light wave when one optical amplifier is driven in the wavelength tunable laser light source according to the first embodiment.
  • 6 is a schematic diagram showing a schematic configuration of a wavelength tunable laser light source according to Embodiment 2.
  • FIG. FIG. 5 is a schematic diagram showing a state of a resonance path of a light wave when one optical amplifier is driven in the wavelength tunable laser light source according to the second embodiment.
  • FIG. 5 is a schematic diagram showing a state of a resonance path of a light wave when one optical amplifier is driven in the wavelength tunable laser light source according to the second embodiment.
  • 6 is a schematic diagram illustrating a schematic configuration of a wavelength tunable laser light source according to Embodiment 3.
  • FIG. 10 is a schematic diagram illustrating a state of a resonance path of a light wave when one optical amplifier is driven in the wavelength tunable laser light source according to the third embodiment.
  • FIG. 10 is a schematic diagram illustrating a state of a resonance path of a light wave when one optical amplifier is driven in the wavelength tunable laser light source according to the third embodiment.
  • 6 is a schematic diagram illustrating a schematic configuration of a wavelength tunable laser light source according to Embodiment 4.
  • FIG. 6 is a schematic diagram showing a schematic configuration of a wavelength tunable laser light source according to Embodiment 5.
  • FIG. 10 is a schematic diagram showing a schematic configuration of a wavelength tunable laser light source
  • the wavelength tunable laser light source of the present invention has a wavelength tunable external resonator that can move the wavelength spectrum peak of transmitted light intensity, and a gain medium that can vary the gain spectrum.
  • the wavelength is varied by changing both the loss spectrum of the external resonator and the gain spectrum of the gain medium.
  • variable wavelength external resonator having a periodic transmission spectrum and the variable gain function configured to selectively change the gain wavelength distribution are used for controlling the oscillation wavelength.
  • the wavelength variable range can be increased as compared with the control using only the variable external resonator as proposed so far.
  • the wavelength tunable laser light source of the present invention includes an external resonator having at least two or more input ports and one or more output ports, and at least two or more connected to the input ports of the external resonator.
  • Gain medium At this time, it is preferable to use two types of gain media having different gain wavelength spectra. Thereby, the wavelength band of laser oscillation can be divided into a short wave side and a long wave side. Therefore, as compared with the conventional case where only one type of gain medium is used, a large gain intensity can be obtained over a wide band, and high-power laser oscillation can be realized.
  • the external resonator has a small variable amount, but enables highly accurate wavelength control.
  • the gain variable function cannot perform fine and high-precision control, but can change the gain by a large variable amount. For this reason, the external resonator can be used for fine adjustment of the wavelength, and the variable gain function can be used for coarse adjustment of the wavelength.
  • the wavelength variable range is large and the wavelength variable operation with high accuracy is possible.
  • the wavelength tunable laser light source of the present invention can have a simple configuration in which two types of gain media are connected in parallel to an external resonator as described above.
  • two types of gain media a system is used in which one of them is driven while the other is not driven, but functions as an absorption passive region. Therefore, it is not necessary to control a particularly complicated gain medium, and the wavelength control of laser oscillation can be easily performed.
  • the wavelength tunable laser light source of the present invention can use a ring-type optical waveguide as the wavelength tunable resonator and two semiconductor amplifiers having different gain spectra as the gain variable medium.
  • a ring-type optical waveguide as the wavelength tunable resonator and two semiconductor amplifiers having different gain spectra as the gain variable medium.
  • the wavelength tunable laser light source of the present invention can change the oscillation wavelength of the laser beam to be output by electrical drive control.
  • the laser light source is composed of a gain medium and a resonator.
  • the oscillation wavelength is mostly changed by tuning the resonance wavelength of the resonator by external control.
  • a resonator generally has transmission or reflection characteristics having a certain wavelength period. Therefore, the tuning range is limited to the wavelength period interval near the peak of the gain wavelength distribution of the gain medium. Even if the wavelength period interval of the resonator is expanded by some method, the optical output is determined according to the gain distribution, so that the optical output is reduced as the tuning range is expanded.
  • the wavelength tunable laser light source of the present invention employs a system in which two gain media having different gain wavelength distributions are provided, and each gain medium is selectively driven according to the oscillation wavelength band to be output. This makes it possible to expand the wavelength variable range without sacrificing the light output.
  • FIG. 1 is a schematic diagram illustrating a schematic configuration of a wavelength tunable laser light source according to the first embodiment.
  • the wavelength tunable laser light source according to the present embodiment includes a wavelength tunable resonator using a planar optical circuit in which a silicon layer is a core layer and an upper silicon oxide film is a cladding layer on an SOI (Silicon on Insulator) substrate 10; It has a configuration in which a semiconductor optical amplifier is hybrid-mounted. Details are described below.
  • the wavelength tunable laser light source includes a wavelength tunable resonator 1, and a first semiconductor optical amplifier 11 and a second semiconductor optical amplifier 12 that are connected in parallel to the wavelength tunable resonator 1, respectively.
  • the wavelength tunable resonator 1 is capable of moving the wavelength spectrum peak of transmitted light intensity, and is also referred to as a wavelength tunable external resonator or a wavelength tunable filter.
  • the wavelength tunable resonator 1 has two input ports and one output port.
  • the tunable resonator 1 includes a ring resonator 2 in which a plurality of ring optical waveguides are optically coupled, and optically via the ring resonator 2 and the optical waveguide. And a 3 dB multiplexer / demultiplexer 16 connected thereto.
  • the first ring-type optical waveguide 21 and the second ring-type optical waveguide 22 are arranged close to the SOI substrate 10 so as to be optically coupled with a predetermined strength.
  • the first ring optical waveguide 21 and the second ring optical waveguide 22 are disposed adjacent to each other along the waveguide direction.
  • the second ring-type optical waveguide 22 has a slightly different peripheral length from the first ring-type optical waveguide 21 and has a different optical path length.
  • a heater 23 for changing the refractive index of the waveguide is formed in a part of the first ring type optical waveguide 21.
  • a heater 24 for changing the refractive index of the waveguide is formed in a part of the second ring type optical waveguide 22.
  • the heaters 23 and 24 are positioned in a range where the temperature of the core layer of the waveguide can be changed, such as above, below, or beside the ring optical waveguide.
  • heaters 23 and 24 are disposed above the first ring optical waveguide 21 and the second ring optical waveguide 22, respectively.
  • an electrode structure other than the heater may be used as long as the electrode structure is used for tuning the wavelength characteristics by changing the refractive index of the waveguide.
  • the first ring-type optical waveguide 21 and the second ring-type optical waveguide 22 constitute the ring-type resonator 2.
  • the ring resonator 2 is a double ring resonator in which two ring optical waveguides are arranged in close proximity to each other in cascade.
  • the second ring-type optical waveguide 22 is disposed close to the optical waveguide 20 so as to be optically coupled. Both ends of the optical waveguide 20 are connected to the input optical waveguide 15 of the 3 dB multiplexer / demultiplexer 16.
  • the output end of the output optical waveguide 17 of the 3 dB multiplexer / demultiplexer 16 is provided with a dielectric multilayer film 18 so as to have a predetermined reflectance.
  • the dielectric multilayer film 18 becomes an optical mirror (semi-mirror) having a predetermined reflectance and transmittance suitable for causing laser oscillation in the wavelength tunable resonator 1 and allowing the laser to be output to the outside.
  • the dielectric multilayer film 18 is formed so as to have a reflectance of 20%, for example.
  • the wavelength tunable resonator 1 is provided with the 3 dB multiplexer / demultiplexer 16 having two input port ends and one output port end.
  • the 3 dB multiplexer / demultiplexer 16 having two input port ends and one output port end is referred to as a 2 ⁇ 1 3 dB multiplexer / demultiplexer 16.
  • the 2 ⁇ 1 3 dB multiplexer / demultiplexer 16 is formed so as to be optically connected to the second ring optical waveguide 22 of the ring resonator 2 via the optical waveguide 20.
  • the output optical waveguide 17 of the 3 dB multiplexer / demultiplexer 16 becomes the output port of the wavelength tunable resonator 1.
  • a dielectric multilayer film 18 which is an optical mirror having a predetermined reflectance and transmittance is provided on the end face of the output port.
  • the portion of the optical waveguide 20 that is coupled to the second ring optical waveguide 22 is formed in a straight line.
  • the first ring-type optical waveguide 21 of the ring-type resonator 2 is disposed close to the optical waveguide 19 so as to be optically coupled.
  • two semiconductor amplifiers first semiconductor optical amplifier 11 and second semiconductor optical amplifier 12 having different gain spectra are disposed so as to be optically coupled to each other. That is, the optical waveguide 19 is optically connected to the first semiconductor optical amplifier 11 at one end and the second semiconductor optical amplifier 12 at the other end, and optically coupled to the first ring optical waveguide 21. It is formed to do.
  • the optical waveguide 19 serves as two input ports of the wavelength tunable resonator 1.
  • the portion of the optical waveguide 19 that is coupled to the first ring optical waveguide 21 is formed in a straight line.
  • the first semiconductor optical amplifier 11 has a gain spectrum on the short wave side and is provided so as to be optically joined to one input port of the wavelength tunable resonator 1.
  • the second semiconductor optical amplifier 12 has a gain spectrum on the long wave side and is provided so as to be optically joined to the other input port of the wavelength tunable resonator 1.
  • the first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12 are optically connected to each other via an optical waveguide 19. Further, highly reflective films 13 and 14 are formed on the opposite end faces of the first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12, respectively.
  • the 3 dB multiplexer / demultiplexer 16 is configured to have a minimum loss at 3 dB, but other multiplexer / demultiplexers can of course be used as the 3 dB multiplexer / demultiplexer 16.
  • FIGS. 2A and 2B are schematic diagrams showing the state of the resonance path of the light wave when one of the optical amplifiers is driven in the wavelength tunable laser light source according to the first embodiment.
  • FIG. 2A is a schematic diagram illustrating an oscillation operation in a long wave band
  • FIG. 2B is a schematic diagram illustrating an oscillation operation in a short wave band.
  • the second semiconductor optical amplifier 12 having a long-waveband gain spectrum is turned on (a state in which a driving current is injected), and the first semiconductor optical amplifier 11 having a short-wave gain spectrum is turned off (a driving current is reduced).
  • FIG. 2A shows the path of the light wave when the injection is not performed.
  • the components that resonate with both the first ring-type optical waveguide 21 and the second ring-type optical waveguide 22 are indicated by dotted lines. Propagate such a route. That is, from the second semiconductor optical amplifier 12, the optical waveguide 19, the first ring optical waveguide 21, the second ring optical waveguide 22, the optical waveguide 20, the input optical waveguide 15, and the 3 dB multiplexer / demultiplexer 16 are sequentially provided. It propagates to the output optical waveguide 17 via. Then, a part of the stimulated emission light propagated on the semi-reflective end face made of the dielectric multilayer film 18 is reflected, and returns to the second semiconductor optical amplifier 12 through the reverse path again. That is, laser oscillation occurs in the resonance path 41 indicated by the dotted line of the wavelength tunable resonator 1.
  • components of the stimulated emission light output from the second semiconductor optical amplifier 12 that do not resonate with the first ring-type optical waveguide 21 and the second ring-type optical waveguide 22 are non-resonant as indicated by the one-dot chain line. Propagates through the resonance path 42. That is, the light is input from the second semiconductor optical amplifier 12 to the first semiconductor optical amplifier 11 via the optical waveguide 19. At this time, the first semiconductor optical amplifier 11 is in an OFF state, and the input non-resonant component is absorbed and does not return to the second semiconductor optical amplifier 12.
  • FIG. 2B shows the path of the light wave when the drive current is not injected.
  • the component that resonates with both the first ring optical waveguide 21 and the second ring optical waveguide 22 is indicated by a dotted line.
  • Propagate such a route That is, from the first semiconductor optical amplifier 11, the optical waveguide 19, the first ring-type optical waveguide 21, the second ring-type optical waveguide 22, the optical waveguide 20, the input optical waveguide 15, and the 3 dB multiplexer / demultiplexer 16 are sequentially provided. It propagates to the output optical waveguide 17 via. Then, a part of the stimulated emission light propagated on the semi-reflecting end face made of the dielectric multilayer film 18 is reflected, and returns to the first semiconductor optical amplifier 11 along the reverse path again. That is, laser oscillation occurs in the resonance path 43 indicated by the dotted line of the wavelength tunable resonator 1.
  • the stimulated emission light output from the first semiconductor optical amplifier 11 components that do not resonate with the first ring-type optical waveguide 21 and the second ring-type optical waveguide 22 are non-resonant as shown by the one-dot chain line. Propagates through the resonance path 44. That is, the light is input from the first semiconductor optical amplifier 11 to the second semiconductor optical amplifier 12 via the optical waveguide 19. At this time, the second semiconductor optical amplifier 12 is in an OFF state, and the input non-resonant component is absorbed and does not return to the first semiconductor optical amplifier 11.
  • the wavelength tunability in the short wave band is a double ring type resonance consisting of the first ring type optical waveguide 21 and the second ring type optical waveguide 22. This is possible within the range of the FSR of the instrument.
  • the wavelength tunable laser light source of the present embodiment changes both the gain spectrum of the first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12 and the loss spectrum of the wavelength tunable resonator 1.
  • the wavelength is varied. That is, in addition to the wavelength tunability by the wavelength tunable resonator 1, the wavelength tunability by two semiconductor optical amplifiers is newly used for wavelength control of laser oscillation. Thereby, the selection range of the wavelength of the light to output can be made wider.
  • the first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12 are selectively driven according to the oscillation wavelength band to be output. This makes it possible to expand the wavelength variable range without sacrificing the light output.
  • the first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12 may be controlled so as to drive one according to a desired wavelength and not drive the other while driving one. No complicated control is required.
  • the first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12 having different gain wavelength spectra are connected in parallel to the wavelength variable resonator 1.
  • the gain variable function obtained by selectively driving the first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12 is combined with the wavelength variable resonator 1 to control the wavelength of laser oscillation. .
  • a large gain intensity can be obtained over a wide band, and high-power laser oscillation can be realized.
  • wavelength tunable resonator 1 that can change the peak position of the loss spectrum within a predetermined range and the gain variable function that can greatly change the gain spectrum shape, particularly the peak position of the gain spectrum, can be used.
  • the wavelength tunable range is large and high output wavelength tunability can be realized by using the control.
  • the wavelength tunable resonator 1 is used for fine adjustment of the wavelength
  • the two semiconductor optical amplifiers can be used for coarse adjustment of the wavelength as a gain variable medium having a large variable amount. Therefore, highly accurate wavelength variable operation is possible.
  • the case where the 2 ⁇ 1 3 dB multiplexer / demultiplexer 16 is used has been described as an example.
  • the 2 ⁇ 2 3 dB multiplexer having two input port ends and two output port ends is used.
  • a duplexer can also be used.
  • one of the two output port ends is subjected to antireflection processing, and the other output port end is provided with a high reflection mirror.
  • a 1 ⁇ 2 3 dB multiplexer / demultiplexer having one input port end and two output port ends connected to each other may be provided.
  • non-reflection processing is applied to one output port end of the 2 ⁇ 2 3 dB multiplexer / demultiplexer, and two output port ends of the 1 ⁇ 2 3 dB multiplexer / demultiplexer are mutually connected to the other output port end.
  • the loop mirror composed of the closed loop waveguide formed by the 1 ⁇ 2 3 dB multiplexer / demultiplexer functions as if it is a high reflection mirror.
  • FIG. 3 is a schematic diagram showing a schematic configuration of the wavelength tunable laser light source according to the second embodiment.
  • the wavelength tunable resonator 1 having a configuration different from that of the first embodiment is provided in the wavelength tunable laser light source.
  • the wavelength tunable resonator 1 according to the present embodiment includes a ring resonator 2 in which a plurality of ring optical waveguides are optically coupled, and optical via the ring resonator 2 and the optical waveguide.
  • an optical switch 52 connected thereto is, instead of the 3 dB multiplexer / demultiplexer 16 of the first embodiment, an optical switch 52 is formed in this embodiment. Since other configurations are the same as those in the first embodiment, description thereof is omitted.
  • the wavelength tunable resonator 1 having two input ports and one output port includes a first semiconductor optical amplifier 11 and a second semiconductor optical amplifier 11 having different gain wavelength spectra.
  • the semiconductor optical amplifiers 12 are connected in parallel.
  • 2 ⁇ 2 having two input port ends and two output port ends so as to be optically connected via the second ring-type optical waveguide 22 and the optical waveguide 20 of the ring-type resonator 2.
  • the optical switch 52 is provided. Specifically, both ends of the optical waveguide 20 disposed so as to be optically coupled to the second ring optical waveguide 22 of the ring resonator 2 are two input optical waveguides of the optical switch 52. 15 are connected to each other.
  • the output end of at least one of the output optical waveguides 17 is provided with a dielectric multilayer film 18 so as to have a predetermined reflectance.
  • the dielectric multilayer film 18 is formed so as to have a reflectance of 20%, for example.
  • the output optical waveguide 17 provided with the dielectric multilayer film 18 serves as an output port of the wavelength tunable resonator 1.
  • a heater 51 for changing the refractive index of the waveguide is formed above the optical waveguide constituting the optical switch 52.
  • FIGS. 4A and 4B are schematic diagrams showing the state of the resonance path of the light wave when one of the optical amplifiers is driven in the wavelength tunable laser light source according to the second embodiment.
  • FIG. 4A is a schematic diagram showing an oscillation operation in a long wave band
  • FIG. 4B is a schematic diagram showing an oscillation operation in a short wave band.
  • the second semiconductor optical amplifier 12 having a long-waveband gain spectrum is turned on (a state in which a driving current is injected), and the first semiconductor optical amplifier 11 having a short-wave gain spectrum is turned off (a driving current is reduced).
  • FIG. 4A shows a light wave path when the injection is not performed.
  • the components that resonate with both the first ring-type optical waveguide 21 and the second ring-type optical waveguide 22 are indicated by dotted lines. Propagate such a route. That is, the optical switch 52 is sequentially passed from the second semiconductor optical amplifier 12 through the optical waveguide 19, the first ring optical waveguide 21, the second ring optical waveguide 22, the optical waveguide 20, and the input optical waveguide 15. Propagate to. In the optical switch 52, the path is adjusted by the heater 51 so that the light is output to the output optical waveguide 17 on the side where the dielectric multilayer film 18 is provided.
  • the path of the optical switch 52 is adjusted in accordance with the semiconductor optical amplifier on the side where the drive current is injected so that the output optical waveguide 17 on the side where the dielectric multilayer film 18 is provided can obtain a desired optical output. Is switched. Thereafter, a part of the stimulated emission light propagated on the semi-reflecting end face made of the dielectric multilayer film 18 is reflected, and returns to the second semiconductor optical amplifier 12 through the reverse path again. That is, laser oscillation occurs in the resonance path 61 indicated by the dotted line of the wavelength tunable resonator 1.
  • components of the stimulated emission light output from the second semiconductor optical amplifier 12 that do not resonate with the first ring-type optical waveguide 21 and the second ring-type optical waveguide 22 are non-resonant as indicated by the one-dot chain line. Propagates through the resonance path 62. That is, the light is input from the second semiconductor optical amplifier 12 to the first semiconductor optical amplifier 11 via the optical waveguide 19. At this time, the first semiconductor optical amplifier 11 is in an OFF state, and the input non-resonant component is absorbed and does not return to the second semiconductor optical amplifier 12.
  • laser oscillation occurs due to the gain distribution on the long wave side, and the wavelength variation in the long wave band is a double ring type resonance composed of the first ring type optical waveguide 21 and the second ring type optical waveguide 22. This is possible within the range of the FSR of the instrument.
  • the first semiconductor optical amplifier 11 having the gain spectrum in the short wave band is turned on (the state in which the drive current is injected), and the second semiconductor optical amplifier 12 having the gain spectrum on the long wave side is turned off.
  • FIG. 4B shows a lightwave path when the drive current is not injected.
  • the component that resonates with both the first ring optical waveguide 21 and the second ring optical waveguide 22 is indicated by a dotted line.
  • the optical switch 52 is sequentially passed from the second semiconductor optical amplifier 12 through the optical waveguide 19, the first ring optical waveguide 21, the second ring optical waveguide 22, the optical waveguide 20, and the input optical waveguide 15. Propagate to.
  • the path is adjusted by the heater 51 so that the light is output to the output optical waveguide 17 on the side where the dielectric multilayer film 18 is provided.
  • the path of the optical switch 52 is adjusted in accordance with the semiconductor optical amplifier on the side where the drive current is injected so that the output optical waveguide 17 on the side where the dielectric multilayer film 18 is provided can obtain a desired optical output. Is switched. Thereafter, a part of the stimulated emission light propagated on the semi-reflecting end face made of the dielectric multilayer film 18 is reflected, and returns to the first semiconductor optical amplifier 11 along the reverse path again. That is, laser oscillation occurs in the resonance path 63 indicated by the dotted line of the wavelength tunable resonator 1.
  • the stimulated emission light output from the first semiconductor optical amplifier 11 components that do not resonate with the first ring-type optical waveguide 21 and the second ring-type optical waveguide 22 are non-resonant as shown by the one-dot chain line. It propagates through the resonance path 64. That is, the light is input from the first semiconductor optical amplifier 11 to the second semiconductor optical amplifier 12 via the optical waveguide 19. At this time, the second semiconductor optical amplifier 12 is in an OFF state, and the input non-resonant component is absorbed and does not return to the first semiconductor optical amplifier 11.
  • the wavelength tunability in the short wave band is a double ring type resonance consisting of the first ring type optical waveguide 21 and the second ring type optical waveguide 22. This is possible within the range of the FSR of the instrument.
  • variable wavelength resonator 1 having a configuration in which the ring type resonator 2 is combined with the optical switch 52 is used.
  • the optical switch 52 instead of the 3 dB multiplexer / demultiplexer 16, it is possible to avoid the 3 dB excess loss that occurs in principle in the 3 dB multiplexer / demultiplexer 16. Therefore, the internal excess loss of the wavelength tunable resonator 1 can be reduced in the wavelength tunable laser light source. Further, the same effects as those of the first embodiment can be obtained.
  • FIG. 5 is a schematic diagram showing a schematic configuration of a wavelength tunable laser light source according to the third embodiment.
  • the wavelength tunable resonator 1 having a configuration different from that of the first embodiment is provided in the wavelength tunable laser light source.
  • the wavelength tunable resonator 1 of the present embodiment includes a ring resonator 3 in which a plurality of ring optical waveguides are optically coupled, and optical via the ring resonator 3 and the optical waveguide. And a 3 dB multiplexer / demultiplexer 16 connected to each other.
  • the ring resonator 3 of the present embodiment has three ring optical waveguides (first ring optical waveguide 31, first ring optical waveguide 31).
  • the wavelength tunable resonator 1 having two input ports and one output port includes a first semiconductor optical amplifier 11 and a second semiconductor optical amplifier 11 having different gain wavelength spectra.
  • the semiconductor optical amplifiers 12 are connected in parallel.
  • the SOI substrate 10 includes a second ring-type optical waveguide 32 and a third ring-type optical waveguide 33 that are optically coupled to the first ring-type optical waveguide 31. They are arranged close to each other so as to be optically coupled through the waveguide 37.
  • the optical waveguide 37 is formed in a straight line.
  • the optical waveguide 37 includes a second ring optical waveguide 32 and a third ring optical waveguide 33 at positions symmetrical to each other with respect to the optical proximity coupling position with the first ring optical waveguide 31.
  • the second ring-type optical waveguide 32 and the third ring-type optical waveguide 33 are slightly different in peripheral length from the first ring-type optical waveguide 31 and have different optical path lengths.
  • a heater 34 for changing the refractive index of the waveguide is formed in a part of the first ring type optical waveguide 31.
  • the heater 35 for changing the refractive index of the waveguide is changed to a part of the second ring type optical waveguide 32, and the refractive index of the waveguide is changed to a part of the third ring type optical waveguide 33.
  • the heater 36 for making it form is each formed.
  • the heaters 34, 35, and 36 are located in a range in which the temperature of the core layer of the waveguide can be changed, such as above, below, or beside the ring optical waveguide.
  • heaters 34, 35, and 36 are disposed above the ring-type optical waveguides, respectively.
  • an electrode structure other than the heater may be used as long as the electrode structure is used for tuning the wavelength characteristics by changing the refractive index of the waveguide.
  • the ring resonator 3 in which three ring optical waveguides are optically connected to each other through the linear optical waveguide 37 is used.
  • An optical waveguide 38 is disposed close to the second ring optical waveguide 32 of the ring resonator 3 so as to be optically coupled.
  • the optical waveguide 39 is disposed close to the third ring optical waveguide 33 of the ring resonator 3 so as to be optically coupled.
  • the optical waveguides 38 and 39 are both connected to the 2 ⁇ 1 3 dB multiplexer / demultiplexer 16 and serve as input optical waveguides for the 3 dB multiplexer / demultiplexer 16.
  • a dielectric multilayer film 18 is applied to the output end of the output optical waveguide 17 of the 3 dB multiplexer / demultiplexer 16 so as to have a predetermined reflectance.
  • the dielectric multilayer film 18 is applied so as to have a reflectance of 20%, for example.
  • the portion of the optical waveguide 38 that is coupled to the second ring type optical waveguide 32 and the portion of the optical waveguide 39 that is coupled to the third ring type optical waveguide 33 are linearly formed.
  • the optical waveguide 19 is disposed close to the first ring optical waveguide 31 of the ring resonator 3 so as to be optically coupled.
  • two semiconductor amplifiers first semiconductor optical amplifier 11 and second semiconductor optical amplifier 12
  • first semiconductor optical amplifier 11 and second semiconductor optical amplifier 12 having different gain spectra are optically coupled to both ends of the optical waveguide 19, respectively. Is arranged.
  • the portion of the optical waveguide 19 that is coupled to the first ring optical waveguide 31 is formed in a straight line.
  • FIGS. 6A and 6B are schematic diagrams showing the state of the resonance path of the light wave when one of the optical amplifiers is driven in the wavelength tunable laser light source according to the third embodiment.
  • FIG. 6A is a schematic diagram showing an oscillation operation in a long wave band
  • FIG. 6B is a schematic diagram showing an oscillation operation in a short wave band.
  • the second semiconductor optical amplifier 12 having a long-waveband gain spectrum is turned on (a state in which a driving current is injected), and the first semiconductor optical amplifier 11 having a short-wave gain spectrum is turned off (a driving current is reduced).
  • FIG. 6A shows the path of the light wave when it is not injected.
  • the components that resonate with both the first ring-type optical waveguide 31 and the third ring-type optical waveguide 33 are indicated by dotted lines. Propagation through various routes. That is, the second semiconductor optical amplifier 12 is sequentially passed through the optical waveguide 19, the first ring optical waveguide 31, the optical waveguide 37, the third ring optical waveguide 33, the optical waveguide 39, and the 3 dB multiplexer / demultiplexer 16. Then, it propagates to the output optical waveguide 17. Then, a part of the stimulated emission light propagated on the semi-reflective end face made of the dielectric multilayer film 18 is reflected, and returns to the second semiconductor optical amplifier 12 through the reverse path again. That is, laser oscillation occurs in the resonance path 81 indicated by the dotted line of the wavelength tunable resonator 1.
  • components of the stimulated emission light output from the second semiconductor optical amplifier that do not resonate with the first ring-type optical waveguide 31 and the third ring-type optical waveguide 33 are non-resonant as indicated by the alternate long and short dash line.
  • Propagate path 82 That is, the light is input from the second semiconductor optical amplifier 12 to the first semiconductor optical amplifier 11 via the optical waveguide 19. At this time, the first semiconductor optical amplifier 11 is in an OFF state, and the input non-resonant component is absorbed and does not return to the second semiconductor optical amplifier 12.
  • laser oscillation occurs due to the gain distribution on the long wave side, and the wavelength variation of the long wave band is a double ring resonator composed of the first ring optical waveguide 31 and the third ring optical waveguide 33. This is possible within the range of FSR.
  • the first semiconductor optical amplifier 11 having a short-waveband gain spectrum is turned on (a state in which a drive current is injected), and the second semiconductor optical amplifier 12 having a long-wave gain spectrum is turned off ( FIG. 6B shows the lightwave path when the drive current is not injected.
  • the component that resonates with both the first ring type optical waveguide 31 and the second ring type optical waveguide 32 is indicated by a dotted line.
  • the first semiconductor optical amplifier 11 is sequentially passed through the optical waveguide 19, the first ring optical waveguide 31, the optical waveguide 37, the second ring optical waveguide 32, the optical waveguide 38, and the 3 dB multiplexer / demultiplexer 16. Then, it propagates to the output optical waveguide 17. Then, a part of the stimulated emission light propagated on the semi-reflecting end face made of the dielectric multilayer film 18 is reflected, and returns to the first semiconductor optical amplifier 11 along the reverse path again. That is, laser oscillation occurs in the resonance path 83 indicated by the dotted line of the wavelength tunable resonator 1.
  • components of the stimulated emission light output from the first semiconductor optical amplifier 11 that do not resonate with the first ring-type optical waveguide 31 and the second ring-type optical waveguide 32 are non-resonant as indicated by a one-dot chain line. Propagates through the resonance path 84. That is, the light is input from the first semiconductor optical amplifier 11 to the second semiconductor optical amplifier 12 via the optical waveguide 19. At this time, the second semiconductor optical amplifier 12 is in an OFF state, and the input non-resonant component is absorbed and does not return to the first semiconductor optical amplifier 11.
  • the wavelength variation of the short wave band is a double ring resonator composed of the first ring type optical waveguide 31 and the second ring type optical waveguide 32. This is possible within the range of FSR.
  • the ring resonator 3 in which the ring optical waveguides are optically coupled via the linear optical waveguide 37 is used.
  • the optical coupling between the ring type optical waveguides can be eliminated. That is, the optical coupling in the wavelength tunable resonator 1 is unified to the optical coupling between the ring type optical waveguide and the linear optical waveguide.
  • the wavelength tunable resonator 1 includes the optical coupling between the ring type optical waveguides and the optical coupling between the ring type optical waveguide and the linear optical waveguide, each coupling strength has a certain level. It is necessary to set the relationship, and stricter manufacturing control is required from the viewpoint of manufacturing accuracy.
  • the wavelength tunable resonator 1 is unified to optical coupling between the ring optical waveguide and the linear optical waveguide, so that the optical coupling between each linear optical waveguide and the ring optical waveguide is integrated.
  • the strength can be set the same in each part. Therefore, the manufacturing control can be made easier. Further, the same effects as those of the first embodiment can be obtained.
  • the third embodiment can be used in combination with the first and second embodiments as appropriate. That is, in the present embodiment, the case where the 2 ⁇ 1 3 dB multiplexer / demultiplexer 16 is used in combination with the ring resonator 3 having three ring optical waveguides has been exemplarily described. However, the present invention is not limited to this.
  • the optical switch 52 shown in the second embodiment may be combined with the ring resonator 3 having three ring optical waveguides.
  • a 2 ⁇ 2 3 dB multiplexer / demultiplexer may be used in combination.
  • FIG. 7 is a schematic diagram showing a schematic configuration of a wavelength tunable laser light source according to the fourth embodiment.
  • a wavelength tunable laser light source that enables miniaturization of the wavelength tunable resonator 1 having two ring optical waveguides and a 3 dB multiplexer / demultiplexer as main components will be described.
  • the wavelength tunable resonator 1 having a configuration different from that of the first embodiment is provided in the wavelength tunable laser light source. Since other configurations are the same as those in the first embodiment, description thereof is omitted. That is, in the present embodiment, similarly to the first embodiment, the wavelength tunable resonator 1 having at least two input ports and one output port includes the first semiconductor optical amplifier 11 having different gain wavelength spectra. The second semiconductor optical amplifier 12 is connected in parallel.
  • the wavelength tunable resonator 1 includes a ring resonator 120 in which two ring optical waveguides having different peripheral lengths are optically connected to each other via an optical waveguide, and the ring resonator 120. And a 3 dB multiplexer / demultiplexer 117 optically connected to each other.
  • the optical waveguide 125 is disposed adjacent to each other so as to be optically coupled to each of the first ring optical waveguide 121 and the second ring optical waveguide 122. That is, one optical waveguide 125 is disposed close to each of the first ring optical waveguide 121 and the second ring optical waveguide 122, whereby the first ring optical waveguide 121 and the second ring optical waveguide 125 are disposed.
  • the optical waveguide 122 is optically connected to each other.
  • the second ring-type optical waveguide 122 has a slightly different peripheral length from the first ring-type optical waveguide 121, and is different in optical path length.
  • the ring resonator 120 is configured by the first ring optical waveguide 121 and the second ring optical waveguide 122 that are optically coupled via the optical waveguide 125.
  • a 2 ⁇ 2 3 dB multiplexer / demultiplexer 117 having two input port ends and two output port ends is disposed in close proximity so as to be optically coupled. That is, the first ring optical waveguide 121 and the second ring optical waveguide 122 are arranged close to each other so as to be optically coupled to the two output optical waveguides 118 and 119 of the 3 dB multiplexer / demultiplexer 117, respectively.
  • the input optical waveguides 115 and 116 of the 3 dB multiplexer / demultiplexer 117 have one ends of two semiconductor optical amplifiers (first semiconductor optical amplifier 11 and second semiconductor optical amplifier 12) having different gain spectra, respectively.
  • the two input optical waveguides 115 and 116 of the 3 dB multiplexer / demultiplexer 117 serve as input ports of the wavelength tunable resonator 1.
  • high reflection films (high reflection dielectric films) 13 and 14 are provided on the opposite end surfaces of the first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12, respectively. It has become.
  • optical waveguide 125 that optically connects the two ring-type optical waveguides is disposed close to the optical waveguide for extracting light wave power so as to be optically coupled.
  • the optical multiplexer / demultiplexer 131 is disposed close to the optical waveguide 125 so as to be optically coupled.
  • An optical antireflection film (not shown) is applied to end faces of the output optical waveguides 132 and 133 of the optical multiplexer / demultiplexer 131 (output optical waveguide ends 134 and 135, respectively).
  • the signal is output from the driven semiconductor optical amplifier.
  • the stimulated emission light is branched into two by a 3 dB multiplexer / demultiplexer 117.
  • the 3 dB multiplexer / demultiplexer 117 only the wavelength component resonating with the first ring optical waveguide 121 and the second ring optical waveguide 122 is again 3 dB multiplexed / divided via the optical waveguide 125. Return to Waver 117. Then, the feedback is made to the driven semiconductor optical amplifier.
  • a highly reflective film is added to one end of the semiconductor optical amplifier, a light wave having a specific wavelength reciprocates between the wavelength tunable resonator 1 including the ring resonator 120 and the semiconductor optical amplifier.
  • laser oscillation occurs.
  • the laser oscillation light is partially coupled to the optical multiplexer / demultiplexer 131 and output from the optical waveguide end face 135 to the outside.
  • the oscillation wavelength can be tuned by the heaters 123 and 124 that are added to the first ring-type optical waveguide 121 and the second ring-type optical waveguide 122 and change the effective refractive index of the waveguide.
  • the wavelength tunable resonator 1 having two ring optical waveguides and a 3 dB multiplexer / demultiplexer 117 as main components can be miniaturized. Further, the same effects as those of the first embodiment can be obtained.
  • FIG. 8 is a schematic diagram showing a schematic configuration of a wavelength tunable laser light source according to the fifth embodiment.
  • an example of a wavelength tunable laser light source having a configuration in which a 2 ⁇ 2 directional coupler type switch is added to the fourth embodiment as means for improving the output light intensity will be described.
  • the wavelength tunable resonator 1 having a configuration different from that of the fourth embodiment is provided in the wavelength tunable laser light source. Since other configurations are the same as those in the fourth embodiment, description thereof is omitted. That is, in the present embodiment, as in the fourth embodiment, the wavelength tunable resonator 1 having at least two input ports and one output port includes the first semiconductor optical amplifier 11 having different gain wavelength spectra. The second semiconductor optical amplifier 12 is connected in parallel.
  • the wavelength tunable resonator 1 of the present embodiment includes a ring resonator 120 in which two ring optical waveguides having different peripheral lengths are optically connected to each other via an optical waveguide, and the ring resonator 120. And a 2 ⁇ 2 3 dB multiplexer / demultiplexer 117 optically connected to each other, and a 2 ⁇ 2 optical switch 150 having two input port ends and two output port ends.
  • the optical waveguide 125 is formed on the SOI substrate 10 so as to be optically coupled to each of the first ring optical waveguide 121 and the second ring optical waveguide 122, as in the fourth embodiment.
  • the ring resonator 120 is configured by being arranged close to each other.
  • the first ring optical waveguide 121 and the second ring optical waveguide 122 are arranged close to each other so as to be optically coupled to the two output optical waveguides 118 and 119 of the 3 dB multiplexer / demultiplexer 117, respectively. Has been.
  • the input optical waveguides 115 and 116 of the 3 dB multiplexer / demultiplexer 117 have one ends of two semiconductor optical amplifiers (first semiconductor optical amplifier 11 and second semiconductor optical amplifier 12) having different gain spectra, respectively. Are optically connected.
  • the other ends of the two semiconductor optical amplifiers are connected to the two input optical waveguides 151 and 152 of the optical switch 150, respectively.
  • the optical switch 150 is a Mach-Zehnder optical switch including two 3 dB multiplexers / demultiplexers 153 and 157, two optical waveguides 154 and 155, and a phase shifter 156.
  • a heater may be used as in the second embodiment.
  • the output end of at least one of the output optical waveguides is provided with a dielectric multilayer film (dielectric film) (not shown) so as to have a predetermined reflectance.
  • a dielectric film having an optical reflectivity of about 5% to 10% is applied to the output optical waveguide end 160 of the output optical waveguide 158, for example.
  • the output optical waveguide end 160 provided with the dielectric film becomes an output port of the wavelength tunable resonator 1.
  • the wavelength tunable laser light source When either the first semiconductor optical amplifier 11 having the short-wave gain spectrum or the second semiconductor optical amplifier 12 having the long-wave gain spectrum is driven, the signal is output from the driven semiconductor optical amplifier.
  • the stimulated emission light propagates through the ring resonator 120 and returns again to the semiconductor optical amplifier on the side where only a specific wavelength light component is driven.
  • the phase of the stimulated emission light guided from the driven semiconductor optical amplifier to the 3 dB multiplexer / demultiplexer 153 of the optical switch 150 is guided by the phase shifter 156 to the output optical waveguide end 160. Then, a part of the light wave component reflected at the output optical waveguide end 160 returns again to the driven semiconductor optical amplifier.
  • an optical resonator is formed between the ring resonator 120 and the output optical waveguide end 160 across the driven semiconductor optical amplifier, and laser oscillation occurs, and the output light is output to the output optical waveguide. It is output from the waveguide end 160.
  • the tunable wavelength band of the laser oscillation light is appropriately selected by operating only one of the two semiconductor optical amplifiers (the first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12) having different gain wavelength bands. It is possible.
  • the output light intensity can be improved in this embodiment. Further, the same effects as those of the first and fourth embodiments can be obtained.
  • FIG. 9 is a schematic diagram showing a schematic configuration of a wavelength tunable laser light source according to the sixth embodiment.
  • an example of a wavelength tunable laser light source in which an optical modulator that converts an electric signal into an optical signal is integrated will be described.
  • the tunable resonator 1 includes a ring resonator 120 in which two ring optical waveguides having different peripheral lengths are optically connected to each other via the optical waveguide, and the ring resonator 120. And a 2 ⁇ 2 3 dB multiplexer / demultiplexer 117 optically connected to each other.
  • the optical waveguide 125 is formed on the SOI substrate 10 so as to be optically coupled to each of the first ring optical waveguide 121 and the second ring optical waveguide 122, as in the fourth embodiment.
  • the ring resonator 120 is configured by being arranged close to each other.
  • the first ring optical waveguide 121 and the second ring optical waveguide 122 are arranged close to each other so as to be optically coupled to the two output optical waveguides 118 and 119 of the 3 dB multiplexer / demultiplexer 117, respectively.
  • heaters 123 and 124 for changing the effective refractive index of the waveguide are formed above the first ring-type optical waveguide 121 and the second ring-type optical waveguide 122, respectively.
  • each of the semiconductor optical amplifier 111 and the optical modulator 112 is optically connected to the input optical waveguides 115 and 116 of the 3 dB multiplexer / demultiplexer 117, respectively.
  • a high reflection film 113 is added to the other end of the semiconductor optical amplifier 111.
  • an antireflection film 114 is added to the other end of the optical modulator 112.
  • the semiconductor optical amplifier 111 When the semiconductor optical amplifier 111 is driven, the stimulated emission light output from the semiconductor optical amplifier 111 propagates through the input optical waveguide 115 and is branched in two directions by the 3 dB multiplexer / demultiplexer 117.
  • the light waves branched by the 3 dB multiplexer / demultiplexer 117 propagate only through the output optical waveguides 118 and 119, respectively, and only light waves having wavelength components that resonate with the first ring optical waveguide 121 and the second ring optical waveguide 122, respectively.
  • a laser wave is oscillated by the reciprocation of the light wave between the high reflection film 113 and the ring resonator 120 via the semiconductor optical amplifier 111, and a part of the oscillation light is optically modulated. It is configured to pass through the device 112 and output to the outside.
  • the wavelength tunable laser light source includes the ring resonator 120 in which two ring optical waveguides having different peripheral lengths are optically connected to each other via the optical waveguide, and the ring resonator 120
  • a wavelength tunable resonator 1 including a 2 ⁇ 2 3 dB multiplexer / demultiplexer 117 optically connected, and a semiconductor optical amplifier 111 and an optical modulator 112 connected in parallel to the wavelength tunable resonator 1 are provided.
  • the optical modulator 112 can be integrated in the same form as the semiconductor optical amplifier 111. Therefore, the mounting process can be shared and the cost can be reduced.
  • the present invention is a light source used for optical communication, optical information processing, optical interconnection, and the like, and can be used for a wavelength variable laser light source having a wavelength variable function and a driving method thereof.

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Abstract

Disclosed is a wavelength-variable laser light source, wherein the wavelength-variable range is expanded with a relatively simple configuration. A method for driving such wavelength-variable laser light source is also provided. The wavelength-variable laser light source is provided with: a wavelength-variable resonator (1), which has a first input port, a second input port and an output port, and can move the wavelength spectral peak of the transmitting light intensity; a first semiconductor optical amplifier (11) having one end thereof optically connected to the first input port of the wavelength-variable resonator (1); a second semiconductor optical amplifier (12), which has one end thereof optically connected to the second input port of the wavelength-variable resonator (1) and has a gain wavelength spectrum different from that of the first semiconductor optical amplifier (11); and a dielectric multilayer film (18) which is provided on the end surface of the output port of the wavelength-variable resonator (1) and has predetermined reflection ratio and transmissivity.

Description

波長可変レーザ光源、及びその駆動方法Wavelength tunable laser light source and driving method thereof
　本発明は、光通信、光情報処理及び光インターコネクション等に用いられる光源であり、特に波長可変機能を有する波長可変レーザ光源、及びその駆動方法に関するものである。 The present invention relates to a light source used for optical communication, optical information processing, optical interconnection, and the like, and more particularly to a wavelength tunable laser light source having a wavelength tunable function and a driving method thereof.
　近年、インターネットのトラフィックは急速に増加しており、これに対応すべく通信容量拡大の技術も進展している。波長分割多重通信（ＷＤＭ：Wavelength Division Multiplexing）は、波長数を増やすことにより大容量化を行うものである。ＷＤＭは、ＲＯＡＤＭ（Reconfigurable Optical Add/Drop Multiplexing）、波長ルーティングによる光クロスコネクト等の進展とあいまって、より柔軟性に優れた通信容量の拡大が活発に検討されている。これは、波長資源を単に容量拡大のみに使用するのではなく、ネットワーク機能の向上にも積極的に利用していくものである。通信容量の拡大と通信方式の高機能化は、相互に関連して、低コストで安全性の高い通信サービスの提供を可能にするものである。波長可変レーザは、このような通信システムを構築する上で重要なキーデバイスの一つである。 In recent years, Internet traffic has been increasing rapidly, and technology to expand communication capacity has also been developed in response to this. Wavelength division multiplex communication (WDM: Wavelength Division Multiplexing) increases the capacity by increasing the number of wavelengths. In WDM, expansion of communication capacity with more flexibility is being actively studied, coupled with progress in ROADM (Reconfigurable Optical Add / Drop Multiplexing), optical cross-connect by wavelength routing, and the like. In this method, wavelength resources are not only used for capacity expansion, but are also actively used for improving network functions. The expansion of the communication capacity and the enhancement of the functions of the communication system enable the provision of a low-cost and highly secure communication service in relation to each other. A tunable laser is one of the key devices important in constructing such a communication system.
　従来の波長分割多重システムでは、一定の波長間隔を有する複数の固定波長光源を並べて対応しており、特に保守管理用バックアップ光源（波長数分）のコストは、システムの低コスト化を阻害する大きな要因となっていた。波長可変光源の適用により、光源の種類を一つに統合することができるので、システムコストの低減が大きく進展することになる。また、切り替え速度の速い波長可変光源は、波長ルーティングにおいても新しいネットワーク機能の実現に必要不可欠な要素となっている。 In conventional wavelength division multiplexing systems, a plurality of fixed wavelength light sources having a fixed wavelength interval are arranged side by side, and the cost of maintenance management backup light sources (for the number of wavelengths) is particularly large, which hinders cost reduction of the system. It was a factor. By applying the wavelength tunable light source, the types of the light sources can be integrated into one, so that the reduction of the system cost is greatly advanced. In addition, a wavelength tunable light source having a high switching speed is an indispensable element for realizing a new network function even in wavelength routing.
　Ｃ（Ｃｏｎｖｅｎｔｉｏｎａｌ）帯域またはＬ（Ｌｏｎｇ）帯域をカバーできる波長可変光源には、可動ＭＥＭＳミラー（Ｍｉｃｒｏ Ｅｌｅｃｔｒｏ Ｍｅｃｈａｎｉｃａｌ Ｓｙｓｔｅｍｓ Ｍｉｒｒｏｒ）を用いたものが、Ｊｉｌｌ　Ｄ．Ｂｅｒｇｅｒ等により、非特許文献１に発表されている。非特許文献１の波長可変光源は、比較的良好な光出力特性を示しているものの、製作コストや耐衝撃性の点でその実用性が懸念されている。また、ＤＢＲ（分布反射型）レーザのモード安定性を高めて、更に変調器と集積化したものがＢ．Ｍａｓｏｎ等により、非特許文献２に報告されているが、低コスト化や信頼性の点で課題がある。 As a wavelength tunable light source that can cover the C (Conventional) band or the L (Long) band, a movable MEMS mirror (Micro Electro Mechanical Systems Mirror) is used. Non-Patent Document 1 is published by Berger et al. Although the wavelength tunable light source of Non-Patent Document 1 shows relatively good light output characteristics, there are concerns about its practicality in terms of manufacturing cost and impact resistance. Further, the mode stability of a DBR (distributed reflection type) laser is improved and further integrated with a modulator. Although reported in Non-Patent Document 2 by Mason et al., There are problems in terms of cost reduction and reliability.
　一方、平面光回路（ＰＬＣ）を外部共振器として用いた波長可変光源では、製作が比較的容易でＭＥＭＳのように可動部を持たない。そのため、製作歩留まり、信頼性（特に耐振動性）の点で優れており、量産性に適していると考えられ、現在のところ幾つかの構成が提案されている。リング型外部共振器と半導体増幅器を用いた構成としては、Ｈ．Ｙａｍａｚａｋｉ等により、非特許文献３において報告されている。非特許文献３の報告によれば、可動部をもたない波長可変光源としては、波長可変範囲、光出力等の面で良好な特性が得られている。 On the other hand, a tunable light source using a planar optical circuit (PLC) as an external resonator is relatively easy to manufacture and does not have a movable part like MEMS. Therefore, it is excellent in terms of production yield and reliability (particularly vibration resistance) and is considered suitable for mass production, and several configurations have been proposed at present. As a configuration using a ring-type external resonator and a semiconductor amplifier, H.K. Reported in Non-Patent Document 3 by Yamazaki et al. According to the report of Non-Patent Document 3, as a wavelength variable light source having no movable part, good characteristics are obtained in terms of wavelength variable range, light output, and the like.
　しかしながら、非特許文献３に提案された構成の波長可変光源では、リング型外部共振器の波長可変範囲と半導体増幅器の利得帯域で波長可変範囲が決まってしまう。そのため、高出力でより広範囲の波長可変を行うには、構成上の限界がある。 However, in the wavelength tunable light source having the configuration proposed in Non-Patent Document 3, the wavelength tunable range is determined by the wavelength tunable range of the ring-type external resonator and the gain band of the semiconductor amplifier. For this reason, there is a structural limitation in performing wavelength tuning over a wide range with high output.
　光通信における高密度波長多重伝送方式（ＤＷＤＭ：Ｄｅｎｓｅ　ＷＤＭ）では、通信波長帯を主にＣ帯域とＬ帯域に分け、それぞれ、およそ４０ｎｍ程度の波長範囲に多くの波長信号光を割り当てている。現在では、多くの波長可変レーザが４０ｎｍの波長範囲を基準に開発が進んでいる。しかし、Ｃ，Ｌ両帯域を一つの光源でカバーできる波長可変範囲８０ｎｍ以上の波長可変レーザは殆どない。また、およそ２０ｎｍ間隔で信号光波長を設定するＣＷＤＭ（Ｃｏａｓｅ　ＷＤＭ）方式では、より広範囲な波長可変が要求されることになる。 In a high-density wavelength division multiplex transmission system (DWDM: Dense WDM) in optical communication, a communication wavelength band is mainly divided into a C band and an L band, and a large number of wavelength signal lights are assigned to a wavelength range of about 40 nm. Currently, many tunable lasers are being developed based on a wavelength range of 40 nm. However, there are few wavelength tunable lasers having a wavelength tunable range of 80 nm or more that can cover both C and L bands with a single light source. Further, in the CWDM (Coarse WDM) system in which signal light wavelengths are set at intervals of about 20 nm, a wider range of wavelength variation is required.
　本発明は、上記のような問題点を解決するためになされたものであり、比較的簡単な構成で、波長可変範囲を拡大することが可能な波長可変レーザ光源、及びその駆動方法を提供することを目的とする。 The present invention has been made to solve the above problems, and provides a wavelength tunable laser light source capable of expanding the wavelength tunable range with a relatively simple configuration, and a driving method thereof. For the purpose.
　本発明の第１の態様にかかる波長可変レーザ光源は、第１入力ポート、第２入力ポート、及び出力ポートを有し、透過光強度の波長スペクトルピークを移動させることのできる波長可変フィルターと、一端が前記第１入力ポートと光学的に接続された第１光増幅器と、一端が前記第２入力ポートと光学的に接続され、前記第１光増幅器と利得波長スペクトルの異なる第２光増幅器と、前記出力ポートの端面に設けられ、所定の反射率及び透過率を有する光学ミラーと、を備えるものである。 A wavelength tunable laser light source according to the first aspect of the present invention includes a first input port, a second input port, and an output port, and a wavelength tunable filter capable of moving a wavelength spectrum peak of transmitted light intensity; A first optical amplifier having one end optically connected to the first input port; a second optical amplifier having one end optically connected to the second input port and having a gain wavelength spectrum different from that of the first optical amplifier; And an optical mirror provided on the end face of the output port and having a predetermined reflectance and transmittance.
　また、本発明の第２の態様にかかる波長可変レーザ光源の駆動方法は、上述の波長可変レーザ光源の駆動方法であって、所望する波長に応じて、前記第１光増幅器及び前記第２光増幅器のうちの一方に電流注入を行うと同時に、他方には電流注入を行わないことを特徴とするものである。 A wavelength tunable laser light source driving method according to the second aspect of the present invention is the above-described wavelength tunable laser light source driving method, wherein the first optical amplifier and the second light are selected according to a desired wavelength. It is characterized in that current is injected into one of the amplifiers and at the same time no current is injected into the other.
　本発明によれば、比較的簡単な構成で、波長可変範囲を拡大することが可能な波長可変レーザ光源、及びその駆動方法を提供することができる。 According to the present invention, it is possible to provide a wavelength tunable laser light source capable of expanding the wavelength tunable range with a relatively simple configuration, and a driving method thereof.
実施の形態１に係る波長可変レーザ光源の概略構成を示す模式図である。2 is a schematic diagram showing a schematic configuration of a wavelength tunable laser light source according to Embodiment 1. FIG. 実施の形態１に係る波長可変レーザ光源において、片方の光増幅器を駆動させた場合の光波の共振経路の様子を示す模式図である。FIG. 3 is a schematic diagram illustrating a state of a resonance path of a light wave when one optical amplifier is driven in the wavelength tunable laser light source according to the first embodiment. 実施の形態１に係る波長可変レーザ光源において、片方の光増幅器を駆動させた場合の光波の共振経路の様子を示す模式図である。FIG. 3 is a schematic diagram illustrating a state of a resonance path of a light wave when one optical amplifier is driven in the wavelength tunable laser light source according to the first embodiment. 実施の形態２に係る波長可変レーザ光源の概略構成を示す模式図である。6 is a schematic diagram showing a schematic configuration of a wavelength tunable laser light source according to Embodiment 2. FIG. 実施の形態２に係る波長可変レーザ光源において、片方の光増幅器を駆動させた場合の光波の共振経路の様子を示す模式図である。FIG. 5 is a schematic diagram showing a state of a resonance path of a light wave when one optical amplifier is driven in the wavelength tunable laser light source according to the second embodiment. 実施の形態２に係る波長可変レーザ光源において、片方の光増幅器を駆動させた場合の光波の共振経路の様子を示す模式図である。FIG. 5 is a schematic diagram showing a state of a resonance path of a light wave when one optical amplifier is driven in the wavelength tunable laser light source according to the second embodiment. 実施の形態３に係る波長可変レーザ光源の概略構成を示す模式図である。6 is a schematic diagram illustrating a schematic configuration of a wavelength tunable laser light source according to Embodiment 3. FIG. 実施の形態３に係る波長可変レーザ光源において、片方の光増幅器を駆動させた場合の光波の共振経路の様子を示す模式図である。FIG. 10 is a schematic diagram illustrating a state of a resonance path of a light wave when one optical amplifier is driven in the wavelength tunable laser light source according to the third embodiment. 実施の形態３に係る波長可変レーザ光源において、片方の光増幅器を駆動させた場合の光波の共振経路の様子を示す模式図である。FIG. 10 is a schematic diagram illustrating a state of a resonance path of a light wave when one optical amplifier is driven in the wavelength tunable laser light source according to the third embodiment. 実施の形態４に係る波長可変レーザ光源の概略構成を示す模式図である。6 is a schematic diagram illustrating a schematic configuration of a wavelength tunable laser light source according to Embodiment 4. FIG. 実施の形態５に係る波長可変レーザ光源の概略構成を示す模式図である。6 is a schematic diagram showing a schematic configuration of a wavelength tunable laser light source according to Embodiment 5. FIG. 実施の形態６に係る波長可変レーザ光源の概略構成を示す模式図である。10 is a schematic diagram showing a schematic configuration of a wavelength tunable laser light source according to Embodiment 6. FIG.
　本発明の波長可変レーザ光源は、透過光強度の波長スペクトルピークを移動させることのできる波長可変外部共振器と、利得スペクトルを可変できる利得媒質とを有している。そして、外部共振器の損失スペクトルと、利得媒質の利得スペクトルとの両方を変化させることにより、波長可変を行うものである。 The wavelength tunable laser light source of the present invention has a wavelength tunable external resonator that can move the wavelength spectrum peak of transmitted light intensity, and a gain medium that can vary the gain spectrum. The wavelength is varied by changing both the loss spectrum of the external resonator and the gain spectrum of the gain medium.
　すなわち、周期的な透過スペクトルを有する波長可変外部共振器と、利得の波長分布を選択的に変更できる構成の利得可変機能との両方を、発振波長の制御に利用する。これにより、これまで提案されているような可変外部共振器のみを用いた制御に比べて、波長可変範囲を大きくすることができる。 That is, both the variable wavelength external resonator having a periodic transmission spectrum and the variable gain function configured to selectively change the gain wavelength distribution are used for controlling the oscillation wavelength. As a result, the wavelength variable range can be increased as compared with the control using only the variable external resonator as proposed so far.
　具体的には、本発明の波長可変レーザ光源は、少なくとも２つ以上の入力ポートと１つ以上の出力ポートを有する外部共振器と、外部共振器の入力ポートに接続された少なくとも２つ以上の利得媒質とを備えている。このとき、利得波長スペクトルの異なる２種類の利得媒質を用いることが好ましい。これにより、レーザ発振の波長帯を短波側と長波側に分けて使用することができる。従って、従来のように１種類の利得媒質のみを使用する場合に比べて、広い帯域にわたって大きな利得強度を得ることができ、高出力のレーザ発振を実現できる。 Specifically, the wavelength tunable laser light source of the present invention includes an external resonator having at least two or more input ports and one or more output ports, and at least two or more connected to the input ports of the external resonator. Gain medium. At this time, it is preferable to use two types of gain media having different gain wavelength spectra. Thereby, the wavelength band of laser oscillation can be divided into a short wave side and a long wave side. Therefore, as compared with the conventional case where only one type of gain medium is used, a large gain intensity can be obtained over a wide band, and high-power laser oscillation can be realized.
　外部共振器は、可変量は小さいが高精度の波長制御が可能である。一方、利得可変機能は、細かく高精度な制御は出来ないが、可変量の大きな利得可変が可能である。そのため、外部共振器を波長の微調整として、また、利得可変機能を波長の粗調整として用いることができる。このように、外部共振器と利得可変機能とを組み合わせて用いることによって、波長可変範囲が大きく、かつ、高精度な波長可変動作が可能である。 The external resonator has a small variable amount, but enables highly accurate wavelength control. On the other hand, the gain variable function cannot perform fine and high-precision control, but can change the gain by a large variable amount. For this reason, the external resonator can be used for fine adjustment of the wavelength, and the variable gain function can be used for coarse adjustment of the wavelength. As described above, by using the external resonator and the gain variable function in combination, the wavelength variable range is large and the wavelength variable operation with high accuracy is possible.
　ここで、本発明の波長可変レーザ光源は、前述したように、２種類の利得媒質が外部共振器に並列して接続された単純な構成とすることができる。この２種類の利得媒質には、一方を駆動させている間、他方は駆動させずに吸収受動領域として機能させる方式が採用される。そのため、特に複雑な利得媒質の制御が必要とならず、レーザ発振の波長制御を簡易に行うことができる。 Here, the wavelength tunable laser light source of the present invention can have a simple configuration in which two types of gain media are connected in parallel to an external resonator as described above. For these two types of gain media, a system is used in which one of them is driven while the other is not driven, but functions as an absorption passive region. Therefore, it is not necessary to control a particularly complicated gain medium, and the wavelength control of laser oscillation can be easily performed.
　また、本発明の波長可変レーザ光源は、波長可変共振器としてリング型光導波路、利得可変媒質として利得スペクトルの異なる２つの半導体増幅器をそれぞれ用いることができる。リング型導波路と２つの半導体増幅器とを同じ化合物半導体基板上に形成することによって、モノリシック集積した波長可変レーザ機能を１つのチップ上に実現することが可能である。そのため、ハイブリット形成時における複雑なモジュール組み立てが必要とならず、低コスト化を図ることができる。 The wavelength tunable laser light source of the present invention can use a ring-type optical waveguide as the wavelength tunable resonator and two semiconductor amplifiers having different gain spectra as the gain variable medium. By forming the ring-type waveguide and the two semiconductor amplifiers on the same compound semiconductor substrate, it is possible to realize a monolithically integrated wavelength tunable laser function on one chip. Therefore, complicated module assembly at the time of hybrid formation is not required, and cost reduction can be achieved.
　このように、本発明の波長可変レーザ光源は、出力するレーザ光の発振波長を電気的な駆動制御により変化させることができる。通常、レーザ光源は利得媒質と共振器から構成されている。特に、波長可変レーザ光源においては、共振器の共振波長を外部制御によりチューニングすることによって発振波長を変化させる場合がほとんどである。共振器は、一般に、ある一定の波長周期をもつ透過あるいは反射特性を有している。そのため、利得媒質の利得波長分布のピーク近傍で、その波長周期間隔にチューニング範囲が限定されることになる。また、共振器の波長周期間隔を何らかの方法で拡大したとしても、利得分布に応じて光出力が決まるため、チューニング範囲の拡大と共に、光出力が低下することになる。 Thus, the wavelength tunable laser light source of the present invention can change the oscillation wavelength of the laser beam to be output by electrical drive control. Usually, the laser light source is composed of a gain medium and a resonator. In particular, in a tunable laser light source, the oscillation wavelength is mostly changed by tuning the resonance wavelength of the resonator by external control. A resonator generally has transmission or reflection characteristics having a certain wavelength period. Therefore, the tuning range is limited to the wavelength period interval near the peak of the gain wavelength distribution of the gain medium. Even if the wavelength period interval of the resonator is expanded by some method, the optical output is determined according to the gain distribution, so that the optical output is reduced as the tuning range is expanded.
　一方、本発明の波長可変レーザ光源では、異なる利得波長分布を有する２つの利得媒質を備え、出力させる発振波長帯に応じて、それぞれの利得媒質を選択的に駆動する方式を採用している。これにより、光出力を犠牲にすることなく波長可変範囲を拡大することが可能となる。 On the other hand, the wavelength tunable laser light source of the present invention employs a system in which two gain media having different gain wavelength distributions are provided, and each gain medium is selectively driven according to the oscillation wavelength band to be output. This makes it possible to expand the wavelength variable range without sacrificing the light output.
　以下、本発明を適用した具体的な実施の形態について、図面を参照しながら詳細に説明する。ただし、本発明が以下の実施形態に限定されるものではない。また、説明の明確化のため、必要に応じて重複説明は省略されている。尚、各図において同一の符号を付されたものは同様の要素を示しており、適宜、説明が省略されている。 Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. For the sake of clarification, duplicate explanation is omitted as necessary. In addition, what attached | subjected the same code | symbol in each figure has shown the same element, and description is abbreviate | omitted suitably.
実施の形態１．
　本発明の第１の実施の形態に係る波長可変レーザ光源の構成について、図１を参照して詳細に説明する。図１は、実施の形態１に係る波長可変レーザ光源の概略構成を示す模式図である。本実施の形態の波長可変レーザ光源は、ＳＯＩ（Ｓｉｌｉｃｏｎ　ｏｎ　ｉｎｓｕｌａｔｏｒ）基板１０には、シリコン層をコア層とし、その上部のシリコン酸化膜をクラッド層とする平面光回路による波長可変共振器と、半導体光増幅器とがハイブリット実装された構成を有している。以下にその詳細を述べる。 Embodiment 1 FIG.
The configuration of the wavelength tunable laser light source according to the first embodiment of the present invention will be described in detail with reference to FIG. FIG. 1 is a schematic diagram illustrating a schematic configuration of a wavelength tunable laser light source according to the first embodiment. The wavelength tunable laser light source according to the present embodiment includes a wavelength tunable resonator using a planar optical circuit in which a silicon layer is a core layer and an upper silicon oxide film is a cladding layer on an SOI (Silicon on Insulator) substrate 10; It has a configuration in which a semiconductor optical amplifier is hybrid-mounted. Details are described below.
　図１において、波長可変レーザ光源は、波長可変共振器１と、この波長可変共振器１にそれぞれ並列して接続された第１の半導体光増幅器１１及び第２の半導体光増幅器１２とを備えている。波長可変共振器１は、透過光強度の波長スペクトルピークを移動させることを可能とするもので、波長可変外部共振器、あるいは波長可変フィルターともいう。波長可変共振器１は、２つの入力ポートと１つの出力ポートを有している。また、本実施の形態では、波長可変共振器１は、複数のリング型光導波路が光学的に結合されたリング型共振器２と、このリング型共振器２と光導波路を介して光学的に接続された３ｄＢ合分波器１６とを有する。 In FIG. 1, the wavelength tunable laser light source includes a wavelength tunable resonator 1, and a first semiconductor optical amplifier 11 and a second semiconductor optical amplifier 12 that are connected in parallel to the wavelength tunable resonator 1, respectively. Yes. The wavelength tunable resonator 1 is capable of moving the wavelength spectrum peak of transmitted light intensity, and is also referred to as a wavelength tunable external resonator or a wavelength tunable filter. The wavelength tunable resonator 1 has two input ports and one output port. In the present embodiment, the tunable resonator 1 includes a ring resonator 2 in which a plurality of ring optical waveguides are optically coupled, and optically via the ring resonator 2 and the optical waveguide. And a 3 dB multiplexer / demultiplexer 16 connected thereto.
　具体的には、ＳＯＩ基板１０には、第１のリング型光導波路２１と第２のリング型光導波路２２とが、所定の強さで光学結合するように近接して配置されている。第１のリング型光導波路２１と第２のリング型光導波路２２は、導波路方向に沿って隣接して配置されている。第２のリング型光導波路２２は、第１のリング型光導波路２１と周囲長が僅かに異なっており、光路長が異なっている。第１のリング型光導波路２１の一部には、導波路の屈折率を変化させるためのヒータ２３が形成されている。同様に、第２のリング型光導波路２２の一部には、導波路の屈折率を変化させるためのヒータ２４が形成されている。ヒータ２３、２４は、リング型光導波路の上、下、または横など、導波路のコア層の温度を変化させることが可能な範囲に位置されている。ここでは、第１のリング型光導波路２１と第２のリング型光導波路２２の上部に、ヒータ２３、２４がそれぞれ配設されている。なお、リング型光導波路近傍にヒータを設ける場合について説明したが、導波路の屈折率を変化させて波長特性をチューニングするための電極構造であればヒータ以外のものを用いてもよい。 Specifically, the first ring-type optical waveguide 21 and the second ring-type optical waveguide 22 are arranged close to the SOI substrate 10 so as to be optically coupled with a predetermined strength. The first ring optical waveguide 21 and the second ring optical waveguide 22 are disposed adjacent to each other along the waveguide direction. The second ring-type optical waveguide 22 has a slightly different peripheral length from the first ring-type optical waveguide 21 and has a different optical path length. A heater 23 for changing the refractive index of the waveguide is formed in a part of the first ring type optical waveguide 21. Similarly, a heater 24 for changing the refractive index of the waveguide is formed in a part of the second ring type optical waveguide 22. The heaters 23 and 24 are positioned in a range where the temperature of the core layer of the waveguide can be changed, such as above, below, or beside the ring optical waveguide. Here, heaters 23 and 24 are disposed above the first ring optical waveguide 21 and the second ring optical waveguide 22, respectively. In addition, although the case where the heater is provided in the vicinity of the ring type optical waveguide has been described, an electrode structure other than the heater may be used as long as the electrode structure is used for tuning the wavelength characteristics by changing the refractive index of the waveguide.
　このように、第１のリング型光導波路２１と第２のリング型光導波路２２とによって、リング型共振器２が構成されている。このリング型共振器２は、２つのリング型光導波路が近接して縦列配置された２重リング型共振器となる。 Thus, the first ring-type optical waveguide 21 and the second ring-type optical waveguide 22 constitute the ring-type resonator 2. The ring resonator 2 is a double ring resonator in which two ring optical waveguides are arranged in close proximity to each other in cascade.
　第２のリング型光導波路２２には、光導波路２０が光学的に結合するように近接して配置されている。この光導波路２０の両端は、３ｄＢ合分波器１６の入力光導波路１５に接続されている。そして、３ｄＢ合分波器１６の出力光導波路１７の出力端は、所定の反射率になるように誘電体多層膜１８が施されている。誘電体多層膜１８は、波長可変共振器１内でレーザ発振を起こさせるとともに、レーザを外部に出力可能とするのに適した所定の反射率及び透過率を有する光学ミラー（半ミラー）となる。ここでは、例えば２０％の反射率となるように、誘電体多層膜１８が形成されている。 The second ring-type optical waveguide 22 is disposed close to the optical waveguide 20 so as to be optically coupled. Both ends of the optical waveguide 20 are connected to the input optical waveguide 15 of the 3 dB multiplexer / demultiplexer 16. The output end of the output optical waveguide 17 of the 3 dB multiplexer / demultiplexer 16 is provided with a dielectric multilayer film 18 so as to have a predetermined reflectance. The dielectric multilayer film 18 becomes an optical mirror (semi-mirror) having a predetermined reflectance and transmittance suitable for causing laser oscillation in the wavelength tunable resonator 1 and allowing the laser to be output to the outside. . Here, the dielectric multilayer film 18 is formed so as to have a reflectance of 20%, for example.
　このように、波長可変共振器１には、２つの入力ポート端と１つの出力ポート端とを有する３ｄＢ合分波器１６が設けられている。以下では、２つの入力ポート端と１つの出力ポート端とを有する３ｄＢ合分波器１６を、２×１の３ｄＢ合分波器１６と呼ぶこととする。２×１の３ｄＢ合分波器１６は、リング型共振器２の第２のリング型光導波路２２と光導波路２０を介して光学的に接続するように形成されている。そして、３ｄＢ合分波器１６の出力光導波路１７が、波長可変共振器１の出力ポートとなる。この出力ポートの端面に、所定の反射率及び透過率を有する光学ミラーである誘電体多層膜１８が設けられている。なお、第２のリング型光導波路２２と結合する部分の光導波路２０は、直線状に形成されている。 As described above, the wavelength tunable resonator 1 is provided with the 3 dB multiplexer / demultiplexer 16 having two input port ends and one output port end. Hereinafter, the 3 dB multiplexer / demultiplexer 16 having two input port ends and one output port end is referred to as a 2 × 1 3 dB multiplexer / demultiplexer 16. The 2 × 1 3 dB multiplexer / demultiplexer 16 is formed so as to be optically connected to the second ring optical waveguide 22 of the ring resonator 2 via the optical waveguide 20. The output optical waveguide 17 of the 3 dB multiplexer / demultiplexer 16 becomes the output port of the wavelength tunable resonator 1. A dielectric multilayer film 18 which is an optical mirror having a predetermined reflectance and transmittance is provided on the end face of the output port. The portion of the optical waveguide 20 that is coupled to the second ring optical waveguide 22 is formed in a straight line.
　一方、リング型共振器２の第１のリング型光導波路２１には、光導波路１９が光学的に結合するように近接して配置されている。この光導波路１９の両端には、利得スペクトルの異なる２つの半導体増幅器（第１の半導体光増幅器１１、第２の半導体光増幅器１２）が、それぞれ光学的に結合するように配置されている。すなわち、光導波路１９は、その一端において第１の半導体光増幅器１１と、他端において第２の半導体光増幅器１２とに互いに光学的に接続し、かつ第１のリング型光導波路２１と光学結合するように形成されている。この光導波路１９が、波長可変共振器１の２つの入力ポートとなる。なお、第１のリング型光導波路２１と結合する部分の光導波路１９は、直線状に形成されている。 On the other hand, the first ring-type optical waveguide 21 of the ring-type resonator 2 is disposed close to the optical waveguide 19 so as to be optically coupled. At both ends of the optical waveguide 19, two semiconductor amplifiers (first semiconductor optical amplifier 11 and second semiconductor optical amplifier 12) having different gain spectra are disposed so as to be optically coupled to each other. That is, the optical waveguide 19 is optically connected to the first semiconductor optical amplifier 11 at one end and the second semiconductor optical amplifier 12 at the other end, and optically coupled to the first ring optical waveguide 21. It is formed to do. The optical waveguide 19 serves as two input ports of the wavelength tunable resonator 1. The portion of the optical waveguide 19 that is coupled to the first ring optical waveguide 21 is formed in a straight line.
　第１の半導体光増幅器１１は、短波側の利得スペクトルを有し、波長可変共振器１の一方の入力ポートと光学的に接合するように設けられている。また、第２の半導体光増幅器１２は、長波側の利得スペクトルを有し、波長可変共振器１の他方の入力ポートと光学的に接合するように設けられている。第１の半導体光増幅器１１と第２の半導体光増幅器１２は、光導波路１９を介して互いに光学的に接続している。更に、第１の半導体光増幅器１１及び第２の半導体光増幅器１２の反対側の端面には、高反射膜１３、１４がそれぞれ形成されている。 The first semiconductor optical amplifier 11 has a gain spectrum on the short wave side and is provided so as to be optically joined to one input port of the wavelength tunable resonator 1. The second semiconductor optical amplifier 12 has a gain spectrum on the long wave side and is provided so as to be optically joined to the other input port of the wavelength tunable resonator 1. The first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12 are optically connected to each other via an optical waveguide 19. Further, highly reflective films 13 and 14 are formed on the opposite end faces of the first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12, respectively.
　なお、３ｄＢ合分波器１６は、３ｄＢのときに損失が最小になる構成となっているが、３ｄＢ合分波器１６として、他の合分波器を用いることも勿論できる。 The 3 dB multiplexer / demultiplexer 16 is configured to have a minimum loss at 3 dB, but other multiplexer / demultiplexers can of course be used as the 3 dB multiplexer / demultiplexer 16.
　続いて、本実施の形態の波長可変レーザ光源の動作機構について、図２Ａ及びＢを用いて詳細に説明する。図２Ａ及びＢは、実施の形態１に係る波長可変レーザ光源において、片方の光増幅器を駆動させた場合の光波の共振経路の様子を示す模式図である。図２Ａは長波帯での発振動作を示す模式図であり、図２Ｂは短波帯での発振動作を示す模式図である。 Subsequently, an operation mechanism of the wavelength tunable laser light source according to the present embodiment will be described in detail with reference to FIGS. 2A and 2B. 2A and 2B are schematic diagrams showing the state of the resonance path of the light wave when one of the optical amplifiers is driven in the wavelength tunable laser light source according to the first embodiment. FIG. 2A is a schematic diagram illustrating an oscillation operation in a long wave band, and FIG. 2B is a schematic diagram illustrating an oscillation operation in a short wave band.
　長波帯の利得スペクトルを有する第２の半導体光増幅器１２をＯＮ状態（駆動電流を注入した状態）にすると共に、短波側の利得スペクトルを有する第１の半導体光増幅器１１をＯＦＦ状態（駆動電流を注入しない状態）にした場合の光波の経路を、図２Ａに示す。 The second semiconductor optical amplifier 12 having a long-waveband gain spectrum is turned on (a state in which a driving current is injected), and the first semiconductor optical amplifier 11 having a short-wave gain spectrum is turned off (a driving current is reduced). FIG. 2A shows the path of the light wave when the injection is not performed.
　第２の半導体光増幅器１２から出力された誘導放出光の波長スペクトル成分の中で、第１のリング型光導波路２１と第２のリング型光導波路２２の両方に共振する成分は、点線に示すような経路を伝搬する。すなわち、第２の半導体光増幅器１２から、光導波路１９、第１のリング型光導波路２１、第２のリング型光導波路２２、光導波路２０、入力光導波路１５、３ｄＢ合分波器１６を順に経由して、出力光導波路１７へと伝搬する。そして、誘電体多層膜１８からなる半反射端面で伝搬した誘導放出光の一部が反射し、再び逆の経路を辿って第２の半導体光増幅器１２に戻ることになる。すなわち、波長可変共振器１の点線で示す共振経路４１でレーザ発振が生じる。 Among the wavelength spectrum components of the stimulated emission light output from the second semiconductor optical amplifier 12, the components that resonate with both the first ring-type optical waveguide 21 and the second ring-type optical waveguide 22 are indicated by dotted lines. Propagate such a route. That is, from the second semiconductor optical amplifier 12, the optical waveguide 19, the first ring optical waveguide 21, the second ring optical waveguide 22, the optical waveguide 20, the input optical waveguide 15, and the 3 dB multiplexer / demultiplexer 16 are sequentially provided. It propagates to the output optical waveguide 17 via. Then, a part of the stimulated emission light propagated on the semi-reflective end face made of the dielectric multilayer film 18 is reflected, and returns to the second semiconductor optical amplifier 12 through the reverse path again. That is, laser oscillation occurs in the resonance path 41 indicated by the dotted line of the wavelength tunable resonator 1.
　一方、第２の半導体光増幅器１２から出力された誘導放出光の中で、第１のリング型光導波路２１と第２のリング型光導波路２２に共振しない成分は、一点鎖線に示すような非共振経路４２を伝搬する。すなわち、第２の半導体光増幅器１２から、光導波路１９を経由して、第１の半導体光増幅器１１に入力されることになる。この時、第１の半導体光増幅器１１はＯＦＦ状態であり、入力された非共振成分は吸収されて、第２の半導体光増幅器１２に戻ることはない。 On the other hand, components of the stimulated emission light output from the second semiconductor optical amplifier 12 that do not resonate with the first ring-type optical waveguide 21 and the second ring-type optical waveguide 22 are non-resonant as indicated by the one-dot chain line. Propagates through the resonance path 42. That is, the light is input from the second semiconductor optical amplifier 12 to the first semiconductor optical amplifier 11 via the optical waveguide 19. At this time, the first semiconductor optical amplifier 11 is in an OFF state, and the input non-resonant component is absorbed and does not return to the second semiconductor optical amplifier 12.
　従って、この動作においては、長波側の利得分布によりレーザ発振が生じ、その長波帯域の波長可変が、第１のリング型光導波路２１と第２のリング型光導波路２２からなる２重リング型共振器のフリースペクトラムレンジ（ＦＳＲ）の範囲で可能となる。 Therefore, in this operation, laser oscillation occurs due to the gain distribution on the long wave side, and the wavelength variation in the long wave band is a double ring type resonance composed of the first ring type optical waveguide 21 and the second ring type optical waveguide 22. This is possible within the free spectrum range (FSR) of the instrument.
　これに対し、短波帯の利得スペクトルを有する第１の半導体光増幅器１１をＯＮ状態（駆動電流を注入した状態）にすると共に、長波側の利得スペクトルを有する第２の半導体光増幅器１２をＯＦＦ状態（駆動電流を注入しない状態）にした場合の光波の経路を、図２Ｂに示す。 On the other hand, the first semiconductor optical amplifier 11 having the gain spectrum in the short wave band is turned on (the state in which the drive current is injected), and the second semiconductor optical amplifier 12 having the gain spectrum on the long wave side is turned off. FIG. 2B shows the path of the light wave when the drive current is not injected.
　第１の半導体光増幅器１１から出力された誘導放出光の波長スペクトル成分の中で、第１のリング型光導波路２１と第２のリング型光導波路２２の両方に共振する成分は、点線に示すような経路を伝搬する。すなわち、第１の半導体光増幅器１１から、光導波路１９、第１のリング型光導波路２１、第２のリング型光導波路２２、光導波路２０、入力光導波路１５、３ｄＢ合分波器１６を順に経由して、出力光導波路１７へと伝搬する。そして、誘電体多層膜１８からなる半反射端面で伝搬した誘導放出光の一部が反射し、再び逆の経路を辿って第１の半導体光増幅器１１に戻ることになる。すなわち、波長可変共振器１の点線で示す共振経路４３でレーザ発振が生じる。 Among the wavelength spectrum components of the stimulated emission light output from the first semiconductor optical amplifier 11, the component that resonates with both the first ring optical waveguide 21 and the second ring optical waveguide 22 is indicated by a dotted line. Propagate such a route. That is, from the first semiconductor optical amplifier 11, the optical waveguide 19, the first ring-type optical waveguide 21, the second ring-type optical waveguide 22, the optical waveguide 20, the input optical waveguide 15, and the 3 dB multiplexer / demultiplexer 16 are sequentially provided. It propagates to the output optical waveguide 17 via. Then, a part of the stimulated emission light propagated on the semi-reflecting end face made of the dielectric multilayer film 18 is reflected, and returns to the first semiconductor optical amplifier 11 along the reverse path again. That is, laser oscillation occurs in the resonance path 43 indicated by the dotted line of the wavelength tunable resonator 1.
　一方、第１の半導体光増幅器１１から出力された誘導放出光の中で、第１のリング型光導波路２１と第２のリング型光導波路２２に共振しない成分は、一点鎖線に示すような非共振経路４４を伝搬する。すなわち、第１の半導体光増幅器１１から、光導波路１９を経由して、第２の半導体光増幅器１２に入力されることになる。この時、第２の半導体光増幅器１２はＯＦＦ状態であり、入力された非共振成分は吸収されて、第１の半導体光増幅器１１に戻ることはない。 On the other hand, in the stimulated emission light output from the first semiconductor optical amplifier 11, components that do not resonate with the first ring-type optical waveguide 21 and the second ring-type optical waveguide 22 are non-resonant as shown by the one-dot chain line. Propagates through the resonance path 44. That is, the light is input from the first semiconductor optical amplifier 11 to the second semiconductor optical amplifier 12 via the optical waveguide 19. At this time, the second semiconductor optical amplifier 12 is in an OFF state, and the input non-resonant component is absorbed and does not return to the first semiconductor optical amplifier 11.
　従って、この動作においては、短波側の利得分布によりレーザ発振が生じ、その短波帯域の波長可変が、第１のリング型光導波路２１と第２のリング型光導波路２２からなる２重リング型共振器のＦＳＲの範囲で可能となる。 Therefore, in this operation, laser oscillation occurs due to the gain distribution on the short wave side, and the wavelength tunability in the short wave band is a double ring type resonance consisting of the first ring type optical waveguide 21 and the second ring type optical waveguide 22. This is possible within the range of the FSR of the instrument.
　このように、本実施の形態の波長可変レーザ光源は、第１の半導体光増幅器１１と第２の半導体光増幅器１２とによる利得スペクトルと、波長可変共振器１の損失スペクトルとの両方を変化させることにより、波長可変を行う。すなわち、波長可変共振器１による波長可変に加え、新たに、２つの半導体光増幅器による波長可変が、レーザ発振の波長制御に利用されることとなる。これにより、出力させる光の波長の選択範囲をより広くすることができる。このとき、本実施の形態では、出力させる発振波長帯に応じて、第１の半導体光増幅器１１と第２の半導体光増幅器１２を選択的に駆動するようにする。これにより、光出力を犠牲にすることなく波長可変範囲を拡大することが可能となる。なお、第１の半導体光増幅器１１と第２の半導体光増幅器１２は、所望する波長に応じて一方を駆動させ、一方を駆動させている間、他方を駆動させないように制御すればよいので、特に複雑な制御は必要ない。 As described above, the wavelength tunable laser light source of the present embodiment changes both the gain spectrum of the first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12 and the loss spectrum of the wavelength tunable resonator 1. Thus, the wavelength is varied. That is, in addition to the wavelength tunability by the wavelength tunable resonator 1, the wavelength tunability by two semiconductor optical amplifiers is newly used for wavelength control of laser oscillation. Thereby, the selection range of the wavelength of the light to output can be made wider. At this time, in the present embodiment, the first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12 are selectively driven according to the oscillation wavelength band to be output. This makes it possible to expand the wavelength variable range without sacrificing the light output. The first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12 may be controlled so as to drive one according to a desired wavelength and not drive the other while driving one. No complicated control is required.
　以上のように、本実施の形態では、互いに利得波長スペクトルの異なる第１の半導体光増幅器１１と第２の半導体光増幅器１２とを、波長可変共振器１に並列接続させている。そして、第１の半導体光増幅器１１と第２の半導体光増幅器１２とを選択的に駆動することで得られる利得可変機能を、波長可変共振器１と組み合わせてレーザ発振の波長制御を行っている。これにより、簡便な構成にもかかわらず、出力させる光の波長の選択範囲をより広くすることができる。また、広い帯域にわたって大きな利得強度を得ることができ、高出力のレーザ発振を実現できる。これは、損失スペクトルのピーク位置を所定の範囲で変えることができる波長可変共振器１と、利得スペクトル形状、特に利得スペクトルのピーク位置を大きく変えることができる利得可変機能との両方を発信波長の制御に利用して、波長可変範囲が大きく、かつ、高出力の波長可変を実現できるからである。さらに、波長可変共振器１を波長の微調整として用いる一方、２つの半導体光増幅器を可変量の大きい利得可変媒質として波長の粗調整に用いることができる。そのため、高精度な波長可変動作が可能である。 As described above, in the present embodiment, the first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12 having different gain wavelength spectra are connected in parallel to the wavelength variable resonator 1. The gain variable function obtained by selectively driving the first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12 is combined with the wavelength variable resonator 1 to control the wavelength of laser oscillation. . Thereby, it is possible to widen the selection range of the wavelength of the light to be output in spite of a simple configuration. In addition, a large gain intensity can be obtained over a wide band, and high-power laser oscillation can be realized. This is because both the wavelength tunable resonator 1 that can change the peak position of the loss spectrum within a predetermined range and the gain variable function that can greatly change the gain spectrum shape, particularly the peak position of the gain spectrum, can be used. This is because the wavelength tunable range is large and high output wavelength tunability can be realized by using the control. Furthermore, while the wavelength tunable resonator 1 is used for fine adjustment of the wavelength, the two semiconductor optical amplifiers can be used for coarse adjustment of the wavelength as a gain variable medium having a large variable amount. Therefore, highly accurate wavelength variable operation is possible.
　なお、本実施の形態では、２×１の３ｄＢ合分波器１６を用いる場合について例示的に説明をしたが、２つの入力ポート端と２つの出力ポート端とを有する２×２の３ｄＢ合分波器を用いることもできる。２×２の３ｄＢ合分波器を用いる場合は、２つの出力ポート端のうち、一方の出力ポート端に無反射処理を施し、他方の出力ポート端に高反射ミラーを設ける。あるいは、高反射ミラーの代わりに、１つの入力ポート端と、相互に接続された２つの出力ポート端とを有する１×２の３ｄＢ合分波器を設けてもよい。すなわち、２×２の３ｄＢ合分波器の一方の出力ポート端に無反射処理を施し、他方の出力ポート端には、１×２の３ｄＢ合分波器の２つの出力ポート端が相互に接続された閉ループ状の導波路からなるループミラーを設けてもよい。この１×２の３ｄＢ合分波器によって構成された閉ループ状の導波路からなるループミラーが、高反射ミラーであるかのように機能することとなる。 In this embodiment, the case where the 2 × 1 3 dB multiplexer / demultiplexer 16 is used has been described as an example. However, the 2 × 2 3 dB multiplexer having two input port ends and two output port ends is used. A duplexer can also be used. In the case of using a 2 × 2 3 dB multiplexer / demultiplexer, one of the two output port ends is subjected to antireflection processing, and the other output port end is provided with a high reflection mirror. Alternatively, instead of the high reflection mirror, a 1 × 2 3 dB multiplexer / demultiplexer having one input port end and two output port ends connected to each other may be provided. That is, non-reflection processing is applied to one output port end of the 2 × 2 3 dB multiplexer / demultiplexer, and two output port ends of the 1 × 2 3 dB multiplexer / demultiplexer are mutually connected to the other output port end. You may provide the loop mirror which consists of the connected closed loop-shaped waveguide. The loop mirror composed of the closed loop waveguide formed by the 1 × 2 3 dB multiplexer / demultiplexer functions as if it is a high reflection mirror.
実施の形態２．
　本発明の第２の実施の形態に係る波長可変レーザ光源の構成について、図３を用いて説明する。図３は、実施の形態２に係る波長可変レーザ光源の概略構成を示す模式図である。 Embodiment 2. FIG.
The configuration of the wavelength tunable laser light source according to the second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a schematic diagram showing a schematic configuration of the wavelength tunable laser light source according to the second embodiment.
　本実施の形態では、実施の形態１と異なる構成の波長可変共振器１が、波長可変レーザ光源に設けられている。具体的には、本実施の形態の波長可変共振器１は、複数のリング型光導波路が光学的に結合されたリング型共振器２と、このリング型共振器２と光導波路を介して光学的に接続された光スイッチ５２とを有している。すなわち、実施の形態１の３ｄＢ合分波器１６に代えて、本実施の形態では、光スイッチ５２が形成されている。それ以外の構成については実施の形態１と同様であるため、説明を省略する。なお、本実施の形態では、実施の形態１と同様、２つの入力ポートと１つの出力ポートを有する波長可変共振器１には、互いに利得波長スペクトルの異なる第１の半導体光増幅器１１と第２の半導体光増幅器１２とが並列接続されている。 In the present embodiment, the wavelength tunable resonator 1 having a configuration different from that of the first embodiment is provided in the wavelength tunable laser light source. Specifically, the wavelength tunable resonator 1 according to the present embodiment includes a ring resonator 2 in which a plurality of ring optical waveguides are optically coupled, and optical via the ring resonator 2 and the optical waveguide. And an optical switch 52 connected thereto. That is, instead of the 3 dB multiplexer / demultiplexer 16 of the first embodiment, an optical switch 52 is formed in this embodiment. Since other configurations are the same as those in the first embodiment, description thereof is omitted. In the present embodiment, similarly to the first embodiment, the wavelength tunable resonator 1 having two input ports and one output port includes a first semiconductor optical amplifier 11 and a second semiconductor optical amplifier 11 having different gain wavelength spectra. The semiconductor optical amplifiers 12 are connected in parallel.
　図３において、リング型共振器２の第２のリング型光導波路２２と光導波路２０を介して光学的に接続するように、２つの入力ポート端と２つの出力ポート端とを有する２×２の光スイッチ５２が設けられている。具体的には、リング型共振器２の第２のリング型光導波路２２と光学的に結合するように近接して配置された光導波路２０の両端は、この光スイッチ５２の２つの入力光導波路１５にそれぞれ接続されている。光スイッチ５２の２つの出力光導波路のうち、少なくとも一方の出力光導波路１７の出射端は、所定の反射率になるように誘電体多層膜１８が施されている。ここでは、例えば２０％の反射率となるように、誘電体多層膜１８が形成されている。この誘電体多層膜１８が設けられた出力光導波路１７が、波長可変共振器１の出力ポートとなる。 In FIG. 3, 2 × 2 having two input port ends and two output port ends so as to be optically connected via the second ring-type optical waveguide 22 and the optical waveguide 20 of the ring-type resonator 2. The optical switch 52 is provided. Specifically, both ends of the optical waveguide 20 disposed so as to be optically coupled to the second ring optical waveguide 22 of the ring resonator 2 are two input optical waveguides of the optical switch 52. 15 are connected to each other. Of the two output optical waveguides of the optical switch 52, the output end of at least one of the output optical waveguides 17 is provided with a dielectric multilayer film 18 so as to have a predetermined reflectance. Here, the dielectric multilayer film 18 is formed so as to have a reflectance of 20%, for example. The output optical waveguide 17 provided with the dielectric multilayer film 18 serves as an output port of the wavelength tunable resonator 1.
　また、光スイッチ５２を構成する光導波路の上部には、導波路の屈折率を変化させるためのヒータ５１が形成されている。 Further, a heater 51 for changing the refractive index of the waveguide is formed above the optical waveguide constituting the optical switch 52.
　続いて、本実施の形態の波長可変レーザ光源の動作機構について、図４Ａ及びＢを用いて詳細に説明する。図４Ａ及びＢは、実施の形態２に係る波長可変レーザ光源において、片方の光増幅器を駆動させた場合の光波の共振経路の様子を示す模式図である。図４Ａは長波帯での発振動作を示す模式図であり、図４Ｂは短波帯での発振動作を示す模式図である。 Subsequently, the operation mechanism of the wavelength tunable laser light source according to the present embodiment will be described in detail with reference to FIGS. 4A and 4B. 4A and 4B are schematic diagrams showing the state of the resonance path of the light wave when one of the optical amplifiers is driven in the wavelength tunable laser light source according to the second embodiment. FIG. 4A is a schematic diagram showing an oscillation operation in a long wave band, and FIG. 4B is a schematic diagram showing an oscillation operation in a short wave band.
　長波帯の利得スペクトルを有する第２の半導体光増幅器１２をＯＮ状態（駆動電流を注入した状態）にすると共に、短波側の利得スペクトルを有する第１の半導体光増幅器１１をＯＦＦ状態（駆動電流を注入しない状態）にした場合の光波の経路を、図４Ａに示す。 The second semiconductor optical amplifier 12 having a long-waveband gain spectrum is turned on (a state in which a driving current is injected), and the first semiconductor optical amplifier 11 having a short-wave gain spectrum is turned off (a driving current is reduced). FIG. 4A shows a light wave path when the injection is not performed.
　第２の半導体光増幅器１２から出力された誘導放出光の波長スペクトル成分の中で、第１のリング型光導波路２１と第２のリング型光導波路２２の両方に共振する成分は、点線に示すような経路を伝搬する。すなわち、第２の半導体光増幅器１２から、光導波路１９、第１のリング型光導波路２１、第２のリング型光導波路２２、光導波路２０、入力光導波路１５を順に経由して、光スイッチ５２へと伝搬する。光スイッチ５２では、誘電体多層膜１８が設けられた側の出力光導波路１７に出力されるように、ヒータ５１により経路の調整が行われる。すなわち、誘電体多層膜１８が設けられた側の出力光導波路１７により所望する大きさの光出力が得られるように、駆動電流が注入された側の半導体光増幅器に合わせて光スイッチ５２の経路が切り換えられる。その後、誘電体多層膜１８からなる半反射端面で伝搬した誘導放出光の一部が反射して、再び逆の経路を辿って第２の半導体光増幅器１２に戻ることになる。すなわち、波長可変共振器１の点線で示す共振経路６１でレーザ発振が生じる。 Among the wavelength spectrum components of the stimulated emission light output from the second semiconductor optical amplifier 12, the components that resonate with both the first ring-type optical waveguide 21 and the second ring-type optical waveguide 22 are indicated by dotted lines. Propagate such a route. That is, the optical switch 52 is sequentially passed from the second semiconductor optical amplifier 12 through the optical waveguide 19, the first ring optical waveguide 21, the second ring optical waveguide 22, the optical waveguide 20, and the input optical waveguide 15. Propagate to. In the optical switch 52, the path is adjusted by the heater 51 so that the light is output to the output optical waveguide 17 on the side where the dielectric multilayer film 18 is provided. That is, the path of the optical switch 52 is adjusted in accordance with the semiconductor optical amplifier on the side where the drive current is injected so that the output optical waveguide 17 on the side where the dielectric multilayer film 18 is provided can obtain a desired optical output. Is switched. Thereafter, a part of the stimulated emission light propagated on the semi-reflecting end face made of the dielectric multilayer film 18 is reflected, and returns to the second semiconductor optical amplifier 12 through the reverse path again. That is, laser oscillation occurs in the resonance path 61 indicated by the dotted line of the wavelength tunable resonator 1.
　一方、第２の半導体光増幅器１２から出力された誘導放出光の中で、第１のリング型光導波路２１と第２のリング型光導波路２２に共振しない成分は、一点鎖線に示すような非共振経路６２を伝搬する。すなわち、第２の半導体光増幅器１２から、光導波路１９を経由して、第１の半導体光増幅器１１に入力されることになる。この時、第１の半導体光増幅器１１はＯＦＦ状態であり、入力された非共振成分は吸収されて、第２の半導体光増幅器１２に戻ることはない。 On the other hand, components of the stimulated emission light output from the second semiconductor optical amplifier 12 that do not resonate with the first ring-type optical waveguide 21 and the second ring-type optical waveguide 22 are non-resonant as indicated by the one-dot chain line. Propagates through the resonance path 62. That is, the light is input from the second semiconductor optical amplifier 12 to the first semiconductor optical amplifier 11 via the optical waveguide 19. At this time, the first semiconductor optical amplifier 11 is in an OFF state, and the input non-resonant component is absorbed and does not return to the second semiconductor optical amplifier 12.
　従って、この動作においては、長波側の利得分布によりレーザ発振が生じ、その長波帯域の波長可変が、第１のリング型光導波路２１と第２のリング型光導波路２２からなる２重リング型共振器のＦＳＲの範囲で可能となる。 Therefore, in this operation, laser oscillation occurs due to the gain distribution on the long wave side, and the wavelength variation in the long wave band is a double ring type resonance composed of the first ring type optical waveguide 21 and the second ring type optical waveguide 22. This is possible within the range of the FSR of the instrument.
　これに対し、短波帯の利得スペクトルを有する第１の半導体光増幅器１１をＯＮ状態（駆動電流を注入した状態）にすると共に、長波側の利得スペクトルを有する第２の半導体光増幅器１２をＯＦＦ状態（駆動電流を注入しない状態）にした場合の光波の経路を、図４Ｂに示す。 On the other hand, the first semiconductor optical amplifier 11 having the gain spectrum in the short wave band is turned on (the state in which the drive current is injected), and the second semiconductor optical amplifier 12 having the gain spectrum on the long wave side is turned off. FIG. 4B shows a lightwave path when the drive current is not injected.
　第１の半導体光増幅器１１から出力された誘導放出光の波長スペクトル成分の中で、第１のリング型光導波路２１と第２のリング型光導波路２２の両方に共振する成分は、点線に示すような経路を伝搬する。すなわち、第２の半導体光増幅器１２から、光導波路１９、第１のリング型光導波路２１、第２のリング型光導波路２２、光導波路２０、入力光導波路１５を順に経由して、光スイッチ５２へと伝搬する。光スイッチ５２では、誘電体多層膜１８が設けられた側の出力光導波路１７に出力されるように、ヒータ５１により経路の調整が行われる。すなわち、誘電体多層膜１８が設けられた側の出力光導波路１７により所望する大きさの光出力が得られるように、駆動電流が注入された側の半導体光増幅器に合わせて光スイッチ５２の経路が切り換えられる。その後、誘電体多層膜１８からなる半反射端面で伝搬した誘導放出光の一部が反射して、再び逆の経路を辿って第１の半導体光増幅器１１に戻ることになる。すなわち、波長可変共振器１の点線で示す共振経路６３でレーザ発振が生じる。 Among the wavelength spectrum components of the stimulated emission light output from the first semiconductor optical amplifier 11, the component that resonates with both the first ring optical waveguide 21 and the second ring optical waveguide 22 is indicated by a dotted line. Propagate such a route. That is, the optical switch 52 is sequentially passed from the second semiconductor optical amplifier 12 through the optical waveguide 19, the first ring optical waveguide 21, the second ring optical waveguide 22, the optical waveguide 20, and the input optical waveguide 15. Propagate to. In the optical switch 52, the path is adjusted by the heater 51 so that the light is output to the output optical waveguide 17 on the side where the dielectric multilayer film 18 is provided. That is, the path of the optical switch 52 is adjusted in accordance with the semiconductor optical amplifier on the side where the drive current is injected so that the output optical waveguide 17 on the side where the dielectric multilayer film 18 is provided can obtain a desired optical output. Is switched. Thereafter, a part of the stimulated emission light propagated on the semi-reflecting end face made of the dielectric multilayer film 18 is reflected, and returns to the first semiconductor optical amplifier 11 along the reverse path again. That is, laser oscillation occurs in the resonance path 63 indicated by the dotted line of the wavelength tunable resonator 1.
　一方、第１の半導体光増幅器１１から出力された誘導放出光の中で、第１のリング型光導波路２１と第２のリング型光導波路２２に共振しない成分は、一点鎖線に示すような非共振経路６４を伝搬する。すなわち、第１の半導体光増幅器１１から、光導波路１９を経由して、第２の半導体光増幅器１２に入力されることになる。この時、第２の半導体光増幅器１２はＯＦＦ状態であり、入力された非共振成分は吸収されて、第１の半導体光増幅器１１に戻ることはない。 On the other hand, in the stimulated emission light output from the first semiconductor optical amplifier 11, components that do not resonate with the first ring-type optical waveguide 21 and the second ring-type optical waveguide 22 are non-resonant as shown by the one-dot chain line. It propagates through the resonance path 64. That is, the light is input from the first semiconductor optical amplifier 11 to the second semiconductor optical amplifier 12 via the optical waveguide 19. At this time, the second semiconductor optical amplifier 12 is in an OFF state, and the input non-resonant component is absorbed and does not return to the first semiconductor optical amplifier 11.
　従って、この動作においては、短波側の利得分布によりレーザ発振が生じ、その短波帯域の波長可変が、第１のリング型光導波路２１と第２のリング型光導波路２２からなる２重リング型共振器のＦＳＲの範囲で可能となる。 Therefore, in this operation, laser oscillation occurs due to the gain distribution on the short wave side, and the wavelength tunability in the short wave band is a double ring type resonance consisting of the first ring type optical waveguide 21 and the second ring type optical waveguide 22. This is possible within the range of the FSR of the instrument.
　以上のように、本実施の形態では、リング型共振器２に光スイッチ５２を組み合わせた構成の波長可変共振器１を用いている。３ｄＢ合分波器１６に代えて、光スイッチ５２を利用することにより、３ｄＢ合分波器１６で原理的に生じる３ｄＢの過剰損失を回避できる。従って、波長可変レーザ光源において、波長可変共振器１の内部過剰損失を低減することができる。また、実施の形態１と同様の効果を奏することができる。 As described above, in the present embodiment, the variable wavelength resonator 1 having a configuration in which the ring type resonator 2 is combined with the optical switch 52 is used. By using the optical switch 52 instead of the 3 dB multiplexer / demultiplexer 16, it is possible to avoid the 3 dB excess loss that occurs in principle in the 3 dB multiplexer / demultiplexer 16. Therefore, the internal excess loss of the wavelength tunable resonator 1 can be reduced in the wavelength tunable laser light source. Further, the same effects as those of the first embodiment can be obtained.
実施の形態３．
　本発明の第３の実施の形態に係る波長可変レーザ光源の構成について、図５を用いて説明する。図５は、実施の形態３に係る波長可変レーザ光源の概略構成を示す模式図である。 Embodiment 3 FIG.
A configuration of a wavelength tunable laser light source according to the third embodiment of the present invention will be described with reference to FIG. FIG. 5 is a schematic diagram showing a schematic configuration of a wavelength tunable laser light source according to the third embodiment.
　本実施の形態では、実施の形態１と異なる構成の波長可変共振器１が、波長可変レーザ光源に設けられている。具体的には、本実施の形態の波長可変共振器１は、複数のリング型光導波路が光学的に結合されたリング型共振器３と、このリング型共振器３と光導波路を介して光学的に接続された３ｄＢ合分波器１６とを有している。本実施の形態のリング型共振器３は、２つのリング型光導波路を有する実施の形態１のリング型共振器２と異なり、３つのリング型光導波路（第１のリング型光導波路３１、第２のリング型光導波路３２、第３のリング型光導波路３３）を有している。すなわち、実施の形態１のリング型共振器２に代えて、本実施の形態では、リング型共振器３が形成されていて、それ以外の構成については実施の形態１と同様であるため、説明を省略する。なお、本実施の形態では、実施の形態１と同様、２つの入力ポートと１つの出力ポートを有する波長可変共振器１には、互いに利得波長スペクトルの異なる第１の半導体光増幅器１１と第２の半導体光増幅器１２とが並列接続されている。 In the present embodiment, the wavelength tunable resonator 1 having a configuration different from that of the first embodiment is provided in the wavelength tunable laser light source. Specifically, the wavelength tunable resonator 1 of the present embodiment includes a ring resonator 3 in which a plurality of ring optical waveguides are optically coupled, and optical via the ring resonator 3 and the optical waveguide. And a 3 dB multiplexer / demultiplexer 16 connected to each other. Unlike the ring resonator 2 of the first embodiment having two ring optical waveguides, the ring resonator 3 of the present embodiment has three ring optical waveguides (first ring optical waveguide 31, first ring optical waveguide 31). 2 ring type optical waveguides 32 and a third ring type optical waveguide 33). That is, instead of the ring type resonator 2 of the first embodiment, in this embodiment, the ring type resonator 3 is formed, and other configurations are the same as those of the first embodiment. Is omitted. In the present embodiment, similarly to the first embodiment, the wavelength tunable resonator 1 having two input ports and one output port includes a first semiconductor optical amplifier 11 and a second semiconductor optical amplifier 11 having different gain wavelength spectra. The semiconductor optical amplifiers 12 are connected in parallel.
　具体的には、図５に示すように、ＳＯＩ基板１０には、第１のリング型光導波路３１に対して、第２のリング型光導波路３２と第３のリング型光導波路３３が、光導波路３７を介して光学結合するように近接して配置されている。光導波路３７は、直線状に形成されている。光導波路３７には、第１のリング型光導波路３１との光学的な近接結合の位置に対して互いに対称な位置で、第２のリング型光導波路３２と第３のリング型光導波路３３が光学的近接接合されている。第２のリング型光導波路３２及び第３のリング型光導波路３３は、第１のリング型光導波路３１と周囲長が僅かに異なっており、光路長が異なっている。 Specifically, as shown in FIG. 5, the SOI substrate 10 includes a second ring-type optical waveguide 32 and a third ring-type optical waveguide 33 that are optically coupled to the first ring-type optical waveguide 31. They are arranged close to each other so as to be optically coupled through the waveguide 37. The optical waveguide 37 is formed in a straight line. The optical waveguide 37 includes a second ring optical waveguide 32 and a third ring optical waveguide 33 at positions symmetrical to each other with respect to the optical proximity coupling position with the first ring optical waveguide 31. Optical proximity bonding. The second ring-type optical waveguide 32 and the third ring-type optical waveguide 33 are slightly different in peripheral length from the first ring-type optical waveguide 31 and have different optical path lengths.
　また、第１のリング型光導波路３１の一部には、導波路の屈折率を変化させるためのヒータ３４が形成されている。同様に、第２のリング型光導波路３２の一部に、導波路の屈折率を変化させるためのヒータ３５と、第３のリング型光導波路３３の一部に、導波路の屈折率を変化させるためのヒータ３６とが、それぞれ形成されている。ヒータ３４、３５、３６は、リング型光導波路の上、下、または横など、導波路のコア層の温度を変化させることが可能な範囲に位置されている。ここでは、各リング型光導波路の上部に、ヒータ３４、３５、３６がそれぞれ配設されている。なお、リング型光導波路近傍にヒータを設ける場合について説明したが、導波路の屈折率を変化させて波長特性をチューニングするための電極構造であればヒータ以外のものを用いてもよい。 Further, a heater 34 for changing the refractive index of the waveguide is formed in a part of the first ring type optical waveguide 31. Similarly, the heater 35 for changing the refractive index of the waveguide is changed to a part of the second ring type optical waveguide 32, and the refractive index of the waveguide is changed to a part of the third ring type optical waveguide 33. The heater 36 for making it form is each formed. The heaters 34, 35, and 36 are located in a range in which the temperature of the core layer of the waveguide can be changed, such as above, below, or beside the ring optical waveguide. Here, heaters 34, 35, and 36 are disposed above the ring-type optical waveguides, respectively. In addition, although the case where the heater is provided in the vicinity of the ring type optical waveguide has been described, an electrode structure other than the heater may be used as long as the electrode structure is used for tuning the wavelength characteristics by changing the refractive index of the waveguide.
　このように、本実施の形態では、３つのリング型光導波路が直線状の光導波路３７を介して互いに光学的に接続されたリング型共振器３が用いられている。リング型共振器３の第２のリング型光導波路３２には、光導波路３８が光学的に結合するように近接して配置されている。また、リング型共振器３の第３のリング型光導波路３３には、光導波路３９が光学的に結合するように近接して配置されている。光導波路３８、３９は、ともに２×１の３ｄＢ合分波器１６に接続され、３ｄＢ合分波器１６の入力光導波路となる。３ｄＢ合分波器１６の出力光導波路１７の出力端は、実施の形態１と同様、所定の反射率になるように誘電体多層膜１８が施されている。ここでは、例えば２０％の反射率となるように、誘電体多層膜１８が施されている。なお、第２のリング型光導波路３２と結合する部分の光導波路３８と、第３のリング型光導波路３３と結合する部分の光導波路３９は、直線状に形成されている。 As described above, in this embodiment, the ring resonator 3 in which three ring optical waveguides are optically connected to each other through the linear optical waveguide 37 is used. An optical waveguide 38 is disposed close to the second ring optical waveguide 32 of the ring resonator 3 so as to be optically coupled. Further, the optical waveguide 39 is disposed close to the third ring optical waveguide 33 of the ring resonator 3 so as to be optically coupled. The optical waveguides 38 and 39 are both connected to the 2 × 1 3 dB multiplexer / demultiplexer 16 and serve as input optical waveguides for the 3 dB multiplexer / demultiplexer 16. Similar to the first embodiment, a dielectric multilayer film 18 is applied to the output end of the output optical waveguide 17 of the 3 dB multiplexer / demultiplexer 16 so as to have a predetermined reflectance. Here, the dielectric multilayer film 18 is applied so as to have a reflectance of 20%, for example. The portion of the optical waveguide 38 that is coupled to the second ring type optical waveguide 32 and the portion of the optical waveguide 39 that is coupled to the third ring type optical waveguide 33 are linearly formed.
　一方、リング型共振器３の第１のリング型光導波路３１には、光導波路１９が光学的に結合するように近接して配置されている。この光導波路１９の両端には、実施の形態１と同様、利得スペクトルの異なる２つの半導体増幅器（第１の半導体光増幅器１１、第２の半導体光増幅器１２）が、それぞれ光学的に結合するように配置されている。なお、第１のリング型光導波路３１と結合する部分の光導波路１９は、直線状に形成されている。 On the other hand, the optical waveguide 19 is disposed close to the first ring optical waveguide 31 of the ring resonator 3 so as to be optically coupled. As in the first embodiment, two semiconductor amplifiers (first semiconductor optical amplifier 11 and second semiconductor optical amplifier 12) having different gain spectra are optically coupled to both ends of the optical waveguide 19, respectively. Is arranged. The portion of the optical waveguide 19 that is coupled to the first ring optical waveguide 31 is formed in a straight line.
　続いて、本実施の形態の波長可変レーザ光源の動作機構について、図６Ａ及びＢを用いて詳細に説明する。図６Ａ及びＢは、実施の形態３に係る波長可変レーザ光源において、片方の光増幅器を駆動させた場合の光波の共振経路の様子を示す模式図である。図６Ａは長波帯での発振動作を示す模式図であり、図６Ｂは短波帯での発振動作を示す模式図である。 Subsequently, the operation mechanism of the wavelength tunable laser light source of the present embodiment will be described in detail with reference to FIGS. 6A and 6B. 6A and 6B are schematic diagrams showing the state of the resonance path of the light wave when one of the optical amplifiers is driven in the wavelength tunable laser light source according to the third embodiment. FIG. 6A is a schematic diagram showing an oscillation operation in a long wave band, and FIG. 6B is a schematic diagram showing an oscillation operation in a short wave band.
　長波帯の利得スペクトルを有する第２の半導体光増幅器１２をＯＮ状態（駆動電流を注入した状態）にすると共に、短波側の利得スペクトルを有する第１の半導体光増幅器１１をＯＦＦ状態（駆動電流を注入しない状態）した場合の光波の経路を、図６Ａに示す。 The second semiconductor optical amplifier 12 having a long-waveband gain spectrum is turned on (a state in which a driving current is injected), and the first semiconductor optical amplifier 11 having a short-wave gain spectrum is turned off (a driving current is reduced). FIG. 6A shows the path of the light wave when it is not injected.
　第２の半導体光増幅器から出力された誘導放出光の波長スペクトル成分の中で、第１のリング型光導波路３１と第３のリング型光導波路３３の両方に共振する成分は、点線に示すような経路を伝搬する。すなわち、第２の半導体光増幅器１２から、光導波路１９、第１のリング型光導波路３１、光導波路３７、第３のリング型光導波路３３、光導波路３９、３ｄＢ合分波器１６を順に経由して、出力光導波路１７へと伝搬する。そして、誘電体多層膜１８からなる半反射端面で伝搬した誘導放出光の一部が反射し、再び逆の経路を辿って第２の半導体光増幅器１２に戻ることになる。すなわち、波長可変共振器１の点線で示す共振経路８１でレーザ発振が生じる。 Of the wavelength spectrum components of the stimulated emission light output from the second semiconductor optical amplifier, the components that resonate with both the first ring-type optical waveguide 31 and the third ring-type optical waveguide 33 are indicated by dotted lines. Propagation through various routes. That is, the second semiconductor optical amplifier 12 is sequentially passed through the optical waveguide 19, the first ring optical waveguide 31, the optical waveguide 37, the third ring optical waveguide 33, the optical waveguide 39, and the 3 dB multiplexer / demultiplexer 16. Then, it propagates to the output optical waveguide 17. Then, a part of the stimulated emission light propagated on the semi-reflective end face made of the dielectric multilayer film 18 is reflected, and returns to the second semiconductor optical amplifier 12 through the reverse path again. That is, laser oscillation occurs in the resonance path 81 indicated by the dotted line of the wavelength tunable resonator 1.
　一方、第２の半導体光増幅器から出力された誘導放出光の中で、第１のリング型光導波路３１と第３のリング型光導波路３３に共振しない成分は、一点鎖線に示すような非共振経路８２を伝搬する。すなわち、第２の半導体光増幅器１２から、光導波路１９を経由して、第１の半導体光増幅器１１に入力されることになる。この時、第１の半導体光増幅器１１はＯＦＦ状態であり、入力された非共振成分は吸収されて、第２の半導体光増幅器１２に戻ることはない。 On the other hand, components of the stimulated emission light output from the second semiconductor optical amplifier that do not resonate with the first ring-type optical waveguide 31 and the third ring-type optical waveguide 33 are non-resonant as indicated by the alternate long and short dash line. Propagate path 82. That is, the light is input from the second semiconductor optical amplifier 12 to the first semiconductor optical amplifier 11 via the optical waveguide 19. At this time, the first semiconductor optical amplifier 11 is in an OFF state, and the input non-resonant component is absorbed and does not return to the second semiconductor optical amplifier 12.
　従って、この動作においては、長波側の利得分布によりレーザ発振が生じ、その長波帯域の波長可変が、第１のリング型光導波路３１と第３のリング型光導波路３３からなる２重リング共振器のＦＳＲの範囲で可能となる。 Therefore, in this operation, laser oscillation occurs due to the gain distribution on the long wave side, and the wavelength variation of the long wave band is a double ring resonator composed of the first ring optical waveguide 31 and the third ring optical waveguide 33. This is possible within the range of FSR.
　これに対し、短波帯の利得スペクトルを有する第１の半導体光増幅器１１をＯＮ状態（駆動電流を注入した状態）すると共に、長波側の利得スペクトルを有する第２の半導体光増幅器１２をＯＦＦ状態（駆動電流を注入しない状態）した場合の光波の経路を、図６Ｂに示す。 On the other hand, the first semiconductor optical amplifier 11 having a short-waveband gain spectrum is turned on (a state in which a drive current is injected), and the second semiconductor optical amplifier 12 having a long-wave gain spectrum is turned off ( FIG. 6B shows the lightwave path when the drive current is not injected.
　第１の半導体光増幅器１１から出力された誘導放出光の波長スペクトル成分の中で、第１のリング型光導波路３１と第２のリング型光導波路３２の両方に共振する成分は、点線に示すような経路を伝搬する。すなわち、第１の半導体光増幅器１１から、光導波路１９、第１のリング型光導波路３１、光導波路３７、第２のリング型光導波路３２、光導波路３８、３ｄＢ合分波器１６を順に経由して、出力光導波路１７へと伝搬する。そして、誘電体多層膜１８からなる半反射端面で伝搬した誘導放出光の一部が反射し、再び逆の経路を辿って第１の半導体光増幅器１１に戻ることになる。すなわち、波長可変共振器１の点線で示す共振経路８３でレーザ発振が生じる。 Among the wavelength spectrum components of the stimulated emission light output from the first semiconductor optical amplifier 11, the component that resonates with both the first ring type optical waveguide 31 and the second ring type optical waveguide 32 is indicated by a dotted line. Propagate such a route. That is, the first semiconductor optical amplifier 11 is sequentially passed through the optical waveguide 19, the first ring optical waveguide 31, the optical waveguide 37, the second ring optical waveguide 32, the optical waveguide 38, and the 3 dB multiplexer / demultiplexer 16. Then, it propagates to the output optical waveguide 17. Then, a part of the stimulated emission light propagated on the semi-reflecting end face made of the dielectric multilayer film 18 is reflected, and returns to the first semiconductor optical amplifier 11 along the reverse path again. That is, laser oscillation occurs in the resonance path 83 indicated by the dotted line of the wavelength tunable resonator 1.
　一方、第１の半導体光増幅器１１から出力された誘導放出光の中で、第１のリング型光導波路３１と第２のリング型光導波路３２に共振しない成分は、一点鎖線に示すような非共振経路８４を伝搬する。すなわち、第１の半導体光増幅器１１から、光導波路１９を経由して、第２の半導体光増幅器１２に入力されることになる。この時、第２の半導体光増幅器１２はＯＦＦ状態であり、入力された非共振成分は吸収されて、第１の半導体光増幅器１１に戻ることはない。 On the other hand, components of the stimulated emission light output from the first semiconductor optical amplifier 11 that do not resonate with the first ring-type optical waveguide 31 and the second ring-type optical waveguide 32 are non-resonant as indicated by a one-dot chain line. Propagates through the resonance path 84. That is, the light is input from the first semiconductor optical amplifier 11 to the second semiconductor optical amplifier 12 via the optical waveguide 19. At this time, the second semiconductor optical amplifier 12 is in an OFF state, and the input non-resonant component is absorbed and does not return to the first semiconductor optical amplifier 11.
　従って、この動作においては、短波側の利得分布によりレーザ発振が生じ、その短波帯域の波長可変が、第１のリング型光導波路３１と第２のリング型光導波路３２からなる２重リング共振器のＦＳＲの範囲で可能となる。 Therefore, in this operation, laser oscillation occurs due to the gain distribution on the short wave side, and the wavelength variation of the short wave band is a double ring resonator composed of the first ring type optical waveguide 31 and the second ring type optical waveguide 32. This is possible within the range of FSR.
　以上のように、本実施の形態では、互いのリング型光導波路が直線状の光導波路３７を介して光学結合したリング型共振器３を用いている。これにより、リング型光導波路同士の光学結合を無くすことができる。すなわち、波長可変共振器１における光学結合は、リング型光導波路と直線状の光導波路との光学結合に統一されることとなる。ここで、波長可変共振器１が、リング型光導波路同士の光学結合と、リング型光導波路と直線状の光導波路の光学結合が共存する場合、それぞれの結合の強さには、ある一定の関係を設定する必要があり、製作精度の点からより厳しい製造上の制御が必要となる。本実施の形態では、波長可変共振器１が、リング型光導波路と直線状の光導波路の光学結合に統一されているので、各直線状の光導波路とリング型光導波路の光学的な結合の強さは、それぞれの部分で同一に設定することができる。従って、製造上の制御をより容易にすることができる。また、実施の形態１と同様の効果を奏することができる。 As described above, in the present embodiment, the ring resonator 3 in which the ring optical waveguides are optically coupled via the linear optical waveguide 37 is used. Thereby, the optical coupling between the ring type optical waveguides can be eliminated. That is, the optical coupling in the wavelength tunable resonator 1 is unified to the optical coupling between the ring type optical waveguide and the linear optical waveguide. Here, when the wavelength tunable resonator 1 includes the optical coupling between the ring type optical waveguides and the optical coupling between the ring type optical waveguide and the linear optical waveguide, each coupling strength has a certain level. It is necessary to set the relationship, and stricter manufacturing control is required from the viewpoint of manufacturing accuracy. In the present embodiment, the wavelength tunable resonator 1 is unified to optical coupling between the ring optical waveguide and the linear optical waveguide, so that the optical coupling between each linear optical waveguide and the ring optical waveguide is integrated. The strength can be set the same in each part. Therefore, the manufacturing control can be made easier. Further, the same effects as those of the first embodiment can be obtained.
　なお、実施の形態３は、適宜、実施の形態１、２と組み合わせて用いることができる。すなわち、本実施の形態では、３つのリング型光導波路を有するリング型共振器３に、２×１の３ｄＢ合分波器１６を組み合わせて用いる場合について例示的に説明をしたが、本発明は、これに限定されるものではない。例えば、３つのリング型光導波路を有するリング型共振器３に、実施の形態２で示した光スイッチ５２を組み合わせて用いてもよい。また、２×２の３ｄＢ合分波器を組み合わせて用いることもできる。 The third embodiment can be used in combination with the first and second embodiments as appropriate. That is, in the present embodiment, the case where the 2 × 1 3 dB multiplexer / demultiplexer 16 is used in combination with the ring resonator 3 having three ring optical waveguides has been exemplarily described. However, the present invention is not limited to this. For example, the optical switch 52 shown in the second embodiment may be combined with the ring resonator 3 having three ring optical waveguides. A 2 × 2 3 dB multiplexer / demultiplexer may be used in combination.
実施の形態４．
　本発明の第４の実施の形態に係る波長可変レーザ光源の構成について、図７を用いて説明する。図７は、実施の形態４に係る波長可変レーザ光源の概略構成を示す模式図である。本実施の形態では、２つのリング型光導波路と３ｄＢ合分波器とを主な構成要素とする波長可変共振器１の小型化を可能にする波長可変レーザ光源の例について説明する。 Embodiment 4 FIG.
A configuration of a wavelength tunable laser light source according to the fourth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a schematic diagram showing a schematic configuration of a wavelength tunable laser light source according to the fourth embodiment. In the present embodiment, an example of a wavelength tunable laser light source that enables miniaturization of the wavelength tunable resonator 1 having two ring optical waveguides and a 3 dB multiplexer / demultiplexer as main components will be described.
　本実施の形態では、実施の形態１と異なる構成の波長可変共振器１が、波長可変レーザ光源に設けられている。それ以外の構成については実施の形態１と同様であるため、説明を省略する。すなわち、本実施の形態では、実施の形態１と同様、２つの入力ポートと１つの出力ポートとを少なくとも有する波長可変共振器１には、互いに利得波長スペクトルの異なる第１の半導体光増幅器１１と第２の半導体光増幅器１２とが並列接続されている。 In the present embodiment, the wavelength tunable resonator 1 having a configuration different from that of the first embodiment is provided in the wavelength tunable laser light source. Since other configurations are the same as those in the first embodiment, description thereof is omitted. That is, in the present embodiment, similarly to the first embodiment, the wavelength tunable resonator 1 having at least two input ports and one output port includes the first semiconductor optical amplifier 11 having different gain wavelength spectra. The second semiconductor optical amplifier 12 is connected in parallel.
　図７において、本実施の形態の波長可変共振器１は、周囲長の異なる２つのリング型光導波路が光導波路を介して互いに光学接続されたリング型共振器１２０と、このリング型共振器１２０と光学的に接続された３ｄＢ合分波器１１７とを有している。 In FIG. 7, the wavelength tunable resonator 1 according to the present embodiment includes a ring resonator 120 in which two ring optical waveguides having different peripheral lengths are optically connected to each other via an optical waveguide, and the ring resonator 120. And a 3 dB multiplexer / demultiplexer 117 optically connected to each other.
　具体的には、ＳＯＩ基板１０において、第１のリング型光導波路１２１と第２のリング型光導波路１２２のそれぞれに光学的に結合するように、光導波路１２５が近接して配置されている。すなわち、１本の光導波路１２５が第１のリング型光導波路１２１と第２のリング型光導波路１２２のそれぞれに近接配置されることによって、第１のリング型光導波路１２１と第２のリング型光導波路１２２とが互いに光学接続された構成となっている。第２のリング型光導波路１２２は、第１のリング型光導波路１２１と周囲長が僅かに異なっており、光路長が異なっている。 Specifically, in the SOI substrate 10, the optical waveguide 125 is disposed adjacent to each other so as to be optically coupled to each of the first ring optical waveguide 121 and the second ring optical waveguide 122. That is, one optical waveguide 125 is disposed close to each of the first ring optical waveguide 121 and the second ring optical waveguide 122, whereby the first ring optical waveguide 121 and the second ring optical waveguide 125 are disposed. The optical waveguide 122 is optically connected to each other. The second ring-type optical waveguide 122 has a slightly different peripheral length from the first ring-type optical waveguide 121, and is different in optical path length.
　第１のリング型光導波路１２１と第２のリング型光導波路１２２の近傍には、実施の形態１と同様、導波路の屈折率を変化させるためのヒータ１２３、１２４がそれぞれ形成されている。なお、導波路の屈折率を変化させて波長特性をチューニングするための電極構造であれば、ヒータ以外のものを用いてもよい。このように、光導波路１２５を介して光学的に結合された第１のリング型光導波路１２１と第２のリング型光導波路１２２とによって、リング型共振器１２０が構成されている。 In the vicinity of the first ring-type optical waveguide 121 and the second ring-type optical waveguide 122, heaters 123 and 124 for changing the refractive index of the waveguide are formed in the same manner as in the first embodiment. In addition, as long as the electrode structure is used for tuning the wavelength characteristics by changing the refractive index of the waveguide, a material other than the heater may be used. As described above, the ring resonator 120 is configured by the first ring optical waveguide 121 and the second ring optical waveguide 122 that are optically coupled via the optical waveguide 125.
　リング型共振器１２０には、２つの入力ポート端と２つの出力ポート端とを有する２×２の３ｄＢ合分波器１１７が光学的に結合するように近接して配置されている。すなわち、第１のリング型光導波路１２１と第２のリング型光導波路１２２とが、３ｄＢ合分波器１１７の２つの出力光導波路１１８，１１９にそれぞれ光学的に結合するように近接して配置されている。一方、３ｄＢ合分波器１１７の入力光導波路１１５、１１６には、それぞれ、利得スペクトルの異なる２つの半導体光増幅器（第１の半導体光増幅器１１、第２の半導体光増幅器１２）のそれぞれの一端が光学的に接続されている。従って、３ｄＢ合分波器１１７の２つの入力光導波路１１５，１１６が、波長可変共振器１の入力ポートとなる。なお、実施の形態１と同様、第１の半導体光増幅器１１と第２の半導体光増幅器１２の反対側の端面には高反射膜（高反射誘電体膜）１３，１４がそれぞれ施された構成となっている。 In the ring resonator 120, a 2 × 2 3 dB multiplexer / demultiplexer 117 having two input port ends and two output port ends is disposed in close proximity so as to be optically coupled. That is, the first ring optical waveguide 121 and the second ring optical waveguide 122 are arranged close to each other so as to be optically coupled to the two output optical waveguides 118 and 119 of the 3 dB multiplexer / demultiplexer 117, respectively. Has been. On the other hand, the input optical waveguides 115 and 116 of the 3 dB multiplexer / demultiplexer 117 have one ends of two semiconductor optical amplifiers (first semiconductor optical amplifier 11 and second semiconductor optical amplifier 12) having different gain spectra, respectively. Are optically connected. Accordingly, the two input optical waveguides 115 and 116 of the 3 dB multiplexer / demultiplexer 117 serve as input ports of the wavelength tunable resonator 1. As in the first embodiment, high reflection films (high reflection dielectric films) 13 and 14 are provided on the opposite end surfaces of the first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12, respectively. It has become.
　さらに、２つのリング型光導波路を光学接続する光導波路１２５の一部には、光波パワーを取り出すための光導波路が光学的に結合するように近接して配置されている。ここでは、光導波路１２５に光学的に結合するように、光合分波器１３１が近接して配置されている。そして、光合分波器１３１の出力光導波路１３２、１３３の端面（それぞれ、出力光導波路端１３４、１３５）に、図示しない光学反射防止膜が施されている。 Furthermore, a part of the optical waveguide 125 that optically connects the two ring-type optical waveguides is disposed close to the optical waveguide for extracting light wave power so as to be optically coupled. Here, the optical multiplexer / demultiplexer 131 is disposed close to the optical waveguide 125 so as to be optically coupled. An optical antireflection film (not shown) is applied to end faces of the output optical waveguides 132 and 133 of the optical multiplexer / demultiplexer 131 (output optical waveguide ends 134 and 135, respectively).
　続いて、本実施の形態の波長可変レーザ光源の動作機構について説明する。短波側の利得スペクトルを有する第１の半導体光増幅器１１か長波側の利得スペクトルを有する第２の半導体光増幅器１２のどちらか一方を駆動させると、駆動された側の半導体光増幅器から出力された誘導放出光は３ｄＢ合分波器１１７により２分岐される。３ｄＢ合分波器１１７により分岐されたそれぞれの光波において、第１のリング型光導波路１２１及び第２のリング型光導波路１２２に共振する波長成分のみが、光導波路１２５を介して再び３ｄＢ合分波器１１７へと戻る。そして、駆動されている側の半導体光増幅器に帰還する。 Subsequently, an operation mechanism of the wavelength tunable laser light source according to the present embodiment will be described. When either the first semiconductor optical amplifier 11 having the short-wave gain spectrum or the second semiconductor optical amplifier 12 having the long-wave gain spectrum is driven, the signal is output from the driven semiconductor optical amplifier. The stimulated emission light is branched into two by a 3 dB multiplexer / demultiplexer 117. In each of the light waves branched by the 3 dB multiplexer / demultiplexer 117, only the wavelength component resonating with the first ring optical waveguide 121 and the second ring optical waveguide 122 is again 3 dB multiplexed / divided via the optical waveguide 125. Return to Waver 117. Then, the feedback is made to the driven semiconductor optical amplifier.
　この半導体光増幅器の一端には高反射膜が付加されているので、リング型共振器１２０を含む波長可変共振器１と半導体光増幅器の間を特定波長の光波が往復する。これにより、レーザ発振が生じることになる。レーザ発振光は、光合分波器１３１に部分的に結合されて、光導波路端面１３５から外部に出力される。第１のリング型光導波路１２１及び第２のリング型光導波路１２２に付加された、導波路実効屈折率を変更するためのヒータ１２３、１２４により、発振波長をチューニングすることが可能となる。 Since a highly reflective film is added to one end of the semiconductor optical amplifier, a light wave having a specific wavelength reciprocates between the wavelength tunable resonator 1 including the ring resonator 120 and the semiconductor optical amplifier. As a result, laser oscillation occurs. The laser oscillation light is partially coupled to the optical multiplexer / demultiplexer 131 and output from the optical waveguide end face 135 to the outside. The oscillation wavelength can be tuned by the heaters 123 and 124 that are added to the first ring-type optical waveguide 121 and the second ring-type optical waveguide 122 and change the effective refractive index of the waveguide.
　以上のような構成とすることにより、本実施の形態では、２つのリング型光導波路と３ｄＢ合分波器１１７とを主な構成要素とする波長可変共振器１を小型化できる。また、実施の形態１と同様の効果を奏することができる。 By adopting the configuration as described above, in the present embodiment, the wavelength tunable resonator 1 having two ring optical waveguides and a 3 dB multiplexer / demultiplexer 117 as main components can be miniaturized. Further, the same effects as those of the first embodiment can be obtained.
実施の形態５．
　本発明の第５の実施の形態に係る波長可変レーザ光源の構成について、図８を用いて説明する。図８は、実施の形態５に係る波長可変レーザ光源の概略構成を示す模式図である。本実施の形態では、出力光強度を向上させるための手段として２×２の方向性結合器型スイッチを実施の形態４に付加した構成の波長可変レーザ光源の例について説明する。 Embodiment 5 FIG.
The configuration of the wavelength tunable laser light source according to the fifth embodiment of the present invention will be described with reference to FIG. FIG. 8 is a schematic diagram showing a schematic configuration of a wavelength tunable laser light source according to the fifth embodiment. In the present embodiment, an example of a wavelength tunable laser light source having a configuration in which a 2 × 2 directional coupler type switch is added to the fourth embodiment as means for improving the output light intensity will be described.
　本実施の形態では、実施の形態４と異なる構成の波長可変共振器１が、波長可変レーザ光源に設けられている。それ以外の構成については実施の形態４と同様であるため、説明を省略する。すなわち、本実施の形態では、実施の形態４と同様、２つの入力ポートと１つの出力ポートとを少なくとも有する波長可変共振器１には、互いに利得波長スペクトルの異なる第１の半導体光増幅器１１と第２の半導体光増幅器１２とが並列接続されている。 In the present embodiment, the wavelength tunable resonator 1 having a configuration different from that of the fourth embodiment is provided in the wavelength tunable laser light source. Since other configurations are the same as those in the fourth embodiment, description thereof is omitted. That is, in the present embodiment, as in the fourth embodiment, the wavelength tunable resonator 1 having at least two input ports and one output port includes the first semiconductor optical amplifier 11 having different gain wavelength spectra. The second semiconductor optical amplifier 12 is connected in parallel.
　図８において、本実施の形態の波長可変共振器１は、周囲長の異なる２つのリング型光導波路が光導波路を介して互いに光学接続されたリング型共振器１２０と、このリング型共振器１２０と光学的に接続された２×２の３ｄＢ合分波器１１７と、２つの入力ポート端と２つの出力ポート端とを有する２×２の光スイッチ１５０と、を有している。 In FIG. 8, the wavelength tunable resonator 1 of the present embodiment includes a ring resonator 120 in which two ring optical waveguides having different peripheral lengths are optically connected to each other via an optical waveguide, and the ring resonator 120. And a 2 × 2 3 dB multiplexer / demultiplexer 117 optically connected to each other, and a 2 × 2 optical switch 150 having two input port ends and two output port ends.
　具体的には、ＳＯＩ基板１０には、実施の形態４と同様、第１のリング型光導波路１２１と第２のリング型光導波路１２２のそれぞれに光学的に結合するように、光導波路１２５が近接して配置されることによって、リング型共振器１２０が構成されている。また、第１のリング型光導波路１２１と第２のリング型光導波路１２２とが、３ｄＢ合分波器１１７の２つの出力光導波路１１８，１１９にそれぞれ光学的に結合するように近接して配置されている。そして、３ｄＢ合分波器１１７の入力光導波路１１５、１１６には、それぞれ、利得スペクトルの異なる２つの半導体光増幅器（第１の半導体光増幅器１１、第２の半導体光増幅器１２）のそれぞれの一端が光学的に接続されている。 Specifically, the optical waveguide 125 is formed on the SOI substrate 10 so as to be optically coupled to each of the first ring optical waveguide 121 and the second ring optical waveguide 122, as in the fourth embodiment. The ring resonator 120 is configured by being arranged close to each other. Also, the first ring optical waveguide 121 and the second ring optical waveguide 122 are arranged close to each other so as to be optically coupled to the two output optical waveguides 118 and 119 of the 3 dB multiplexer / demultiplexer 117, respectively. Has been. The input optical waveguides 115 and 116 of the 3 dB multiplexer / demultiplexer 117 have one ends of two semiconductor optical amplifiers (first semiconductor optical amplifier 11 and second semiconductor optical amplifier 12) having different gain spectra, respectively. Are optically connected.
　本実施の形態では、２つの半導体光増幅器（第１の半導体光増幅器１１、第２の半導体光増幅器１２）のそれぞれの他端は、光スイッチ１５０の２つの入力光導波路１５１、１５２にそれぞれ接続されている。この光スイッチ１５０は、２つの３ｄＢ合分波器１５３、１５７と、２本の光導波路１５４、１５５と、位相シフター１５６とを含むマッハツェンダー型光スイッチである。位相シフター１５６の一例として、実施の形態２と同様、ヒータを用いてもよい。光スイッチ１５０の２つの出力光導波路１５８、１５９のうち、少なくとも一方の出力光導波路の出射端は、所定の反射率になるように図示しない誘電体多層膜（誘電体膜）が施されている。ここでは、出力光導波路１５８の出力光導波路端１６０に、例えば光学反射率が５％から１０％程度の誘電体膜が施されている。この誘電体膜の設けられた出力光導波路端１６０が、波長可変共振器１の出力ポートとなる。 In the present embodiment, the other ends of the two semiconductor optical amplifiers (first semiconductor optical amplifier 11 and second semiconductor optical amplifier 12) are connected to the two input optical waveguides 151 and 152 of the optical switch 150, respectively. Has been. The optical switch 150 is a Mach-Zehnder optical switch including two 3 dB multiplexers / demultiplexers 153 and 157, two optical waveguides 154 and 155, and a phase shifter 156. As an example of the phase shifter 156, a heater may be used as in the second embodiment. Of the two output optical waveguides 158 and 159 of the optical switch 150, the output end of at least one of the output optical waveguides is provided with a dielectric multilayer film (dielectric film) (not shown) so as to have a predetermined reflectance. . Here, a dielectric film having an optical reflectivity of about 5% to 10% is applied to the output optical waveguide end 160 of the output optical waveguide 158, for example. The output optical waveguide end 160 provided with the dielectric film becomes an output port of the wavelength tunable resonator 1.
　続いて、本実施の形態の波長可変レーザ光源の動作機構について説明する。短波側の利得スペクトルを有する第１の半導体光増幅器１１か長波側の利得スペクトルを有する第２の半導体光増幅器１２のどちらか一方を駆動させると、駆動された側の半導体光増幅器から出力された誘導放出光は、リング型共振器１２０を伝搬し、特定の波長光成分のみが駆動されている側の半導体光増幅器に再び帰還する。 Subsequently, an operation mechanism of the wavelength tunable laser light source according to the present embodiment will be described. When either the first semiconductor optical amplifier 11 having the short-wave gain spectrum or the second semiconductor optical amplifier 12 having the long-wave gain spectrum is driven, the signal is output from the driven semiconductor optical amplifier. The stimulated emission light propagates through the ring resonator 120 and returns again to the semiconductor optical amplifier on the side where only a specific wavelength light component is driven.
　また、駆動された側の半導体光増幅器から光スイッチ１５０の３ｄＢ合分波器１５３へ導波した誘導放出光は、位相シフター１５６により出力光導波路端１６０へ導波するように位相調整される。そして、この出力光導波路端１６０において反射された一部の光波成分は、駆動されている側の半導体光増幅器へ再び戻ることになる。これにより、駆動されている側の半導体光増幅器を挟んで、リング型共振器１２０と出力光導波路端１６０との間で光共振器が形成されて、レーザ発振が生じ、その出力光が出力光導波路端１６０から出力されることになる。レーザ発振光のチューニング可能な波長帯は、利得波長帯の異なる２つの半導体光増幅器（第１の半導体光増幅器１１、第２の半導体光増幅器１２）のどちらか一方のみ動作させることにより適宜選択することが可能である。 Further, the phase of the stimulated emission light guided from the driven semiconductor optical amplifier to the 3 dB multiplexer / demultiplexer 153 of the optical switch 150 is guided by the phase shifter 156 to the output optical waveguide end 160. Then, a part of the light wave component reflected at the output optical waveguide end 160 returns again to the driven semiconductor optical amplifier. Thus, an optical resonator is formed between the ring resonator 120 and the output optical waveguide end 160 across the driven semiconductor optical amplifier, and laser oscillation occurs, and the output light is output to the output optical waveguide. It is output from the waveguide end 160. The tunable wavelength band of the laser oscillation light is appropriately selected by operating only one of the two semiconductor optical amplifiers (the first semiconductor optical amplifier 11 and the second semiconductor optical amplifier 12) having different gain wavelength bands. It is possible.
　以上のような構成とすることにより、本実施の形態では、出力光強度を向上させることができる。また、実施の形態１、４と同様の効果を奏することができる。 By adopting the above configuration, the output light intensity can be improved in this embodiment. Further, the same effects as those of the first and fourth embodiments can be obtained.
実施の形態６．
　本発明の第６の実施の形態に係る波長可変レーザ光源の構成について、図９を用いて説明する。図９は、実施の形態６に係る波長可変レーザ光源の概略構成を示す模式図である。本実施の形態では、電気信号を光信号に変換する光変調器を集積した波長可変レーザ光源の例について説明する。 Embodiment 6 FIG.
The configuration of a wavelength tunable laser light source according to the sixth embodiment of the present invention will be described with reference to FIG. FIG. 9 is a schematic diagram showing a schematic configuration of a wavelength tunable laser light source according to the sixth embodiment. In this embodiment, an example of a wavelength tunable laser light source in which an optical modulator that converts an electric signal into an optical signal is integrated will be described.
　図９において、本実施の形態の波長可変共振器１は、周囲長の異なる２つのリング型光導波路が光導波路を介して互いに光学接続されたリング型共振器１２０と、このリング型共振器１２０と光学的に接続された２×２の３ｄＢ合分波器１１７と、を有している。 In FIG. 9, the tunable resonator 1 according to the present embodiment includes a ring resonator 120 in which two ring optical waveguides having different peripheral lengths are optically connected to each other via the optical waveguide, and the ring resonator 120. And a 2 × 2 3 dB multiplexer / demultiplexer 117 optically connected to each other.
　具体的には、ＳＯＩ基板１０には、実施の形態４と同様、第１のリング型光導波路１２１と第２のリング型光導波路１２２のそれぞれに光学的に結合するように、光導波路１２５が近接して配置されることによって、リング型共振器１２０が構成されている。また、第１のリング型光導波路１２１と第２のリング型光導波路１２２とが、３ｄＢ合分波器１１７の２つの出力光導波路１１８，１１９にそれぞれ光学的に結合するように近接して配置されている。なお、第１のリング型光導波路１２１と第２のリング型光導波路１２２の上部には、導波路の実効屈折率を変化させるためのヒータ１２３、１２４がそれぞれ形成されている。 Specifically, the optical waveguide 125 is formed on the SOI substrate 10 so as to be optically coupled to each of the first ring optical waveguide 121 and the second ring optical waveguide 122, as in the fourth embodiment. The ring resonator 120 is configured by being arranged close to each other. Also, the first ring optical waveguide 121 and the second ring optical waveguide 122 are arranged close to each other so as to be optically coupled to the two output optical waveguides 118 and 119 of the 3 dB multiplexer / demultiplexer 117, respectively. Has been. In addition, heaters 123 and 124 for changing the effective refractive index of the waveguide are formed above the first ring-type optical waveguide 121 and the second ring-type optical waveguide 122, respectively.
　本実施の形態では、３ｄＢ合分波器１１７の入力光導波路１１５，１１６には、それぞれ、半導体光増幅器１１１と光変調器１１２のそれぞれの一端が光学的に接続されている。半導体光増幅器１１１の他端には、高反射膜１１３が付加されている。一方、光変調器１１２の他端には、反射防止膜１１４が付加されている。 In this embodiment, one end of each of the semiconductor optical amplifier 111 and the optical modulator 112 is optically connected to the input optical waveguides 115 and 116 of the 3 dB multiplexer / demultiplexer 117, respectively. A high reflection film 113 is added to the other end of the semiconductor optical amplifier 111. On the other hand, an antireflection film 114 is added to the other end of the optical modulator 112.
　続いて、本実施の形態の波長可変レーザ光源の動作機構について説明する。半導体光増幅器１１１を駆動させると、この半導体光増幅器１１１から出力された誘導放出光は、入力光導波路１１５を伝搬して３ｄＢ合分波器１１７により２方向に分岐される。３ｄＢ合分波器１１７により分岐された光波は、それぞれ、出力光導波路１１８，１１９を伝搬し、第１のリング型光導波路１２１及び第２のリング型光導波路１２２に共振する波長成分の光波のみが、出力光導波路１１８，１１９を通過して再び３ｄＢ合分波器１１７へと戻る。そして、一部の光波は、入力光導波路１１６を伝搬した後に光変調器１１２に入力される。また、他の光波成分は入力光導波路１１５を伝搬して半導体光増幅器１１１に再帰し、高反射膜１１３で反射される。 Subsequently, an operation mechanism of the wavelength tunable laser light source according to the present embodiment will be described. When the semiconductor optical amplifier 111 is driven, the stimulated emission light output from the semiconductor optical amplifier 111 propagates through the input optical waveguide 115 and is branched in two directions by the 3 dB multiplexer / demultiplexer 117. The light waves branched by the 3 dB multiplexer / demultiplexer 117 propagate only through the output optical waveguides 118 and 119, respectively, and only light waves having wavelength components that resonate with the first ring optical waveguide 121 and the second ring optical waveguide 122, respectively. However, it passes through the output optical waveguides 118 and 119 and returns to the 3 dB multiplexer / demultiplexer 117 again. Then, a part of the light waves are input to the optical modulator 112 after propagating through the input optical waveguide 116. Other light wave components propagate through the input optical waveguide 115, return to the semiconductor optical amplifier 111, and are reflected by the high reflection film 113.
　即ち、本実施の形態では、半導体光増幅器１１１を介して高反射膜１１３とリング型共振器１２０との間で光波の往復が生じることによって、レーザ発振が起こり、発振光の一部が光変調器１１２を通過して外部に出力される構造となっている。 In other words, in this embodiment, a laser wave is oscillated by the reciprocation of the light wave between the high reflection film 113 and the ring resonator 120 via the semiconductor optical amplifier 111, and a part of the oscillation light is optically modulated. It is configured to pass through the device 112 and output to the outside.
　このように、本実施の形態の波長可変レーザ光源は、周囲長の異なる２つのリング型光導波路が光導波路を介して互いに光学接続されたリング型共振器１２０、及びこのリング型共振器１２０と光学的に接続された２×２の３ｄＢ合分波器１１７を含む波長可変共振器１と、この波長可変共振器１に並列接続された半導体光増幅器１１１及び光変調器１１２とを備えて構成されている。これにより、光変調器１１２を半導体光増幅器１１１と同様の形態で集積することが可能である。従って、実装工程の共通化、低コスト化を図ることができる。 As described above, the wavelength tunable laser light source according to the present embodiment includes the ring resonator 120 in which two ring optical waveguides having different peripheral lengths are optically connected to each other via the optical waveguide, and the ring resonator 120 A wavelength tunable resonator 1 including a 2 × 2 3 dB multiplexer / demultiplexer 117 optically connected, and a semiconductor optical amplifier 111 and an optical modulator 112 connected in parallel to the wavelength tunable resonator 1 are provided. Has been. Thereby, the optical modulator 112 can be integrated in the same form as the semiconductor optical amplifier 111. Therefore, the mounting process can be shared and the cost can be reduced.
　以上、実施の形態を参照して本願発明を説明したが、本願発明は上記によって限定されるものではない。本願発明の構成や詳細には、発明のスコープ内で当業者が理解し得る様々な変更をすることができる。 The present invention has been described above with reference to the embodiment, but the present invention is not limited to the above. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the invention.
　この出願は、２００９年６月２９日に出願された日本出願特願２００９－１５３７００を基礎とする優先権を主張し、その開示の全てをここに取り込む。 This application claims priority based on Japanese Patent Application No. 2009-153700 filed on June 29, 2009, the entire disclosure of which is incorporated herein.
　本発明は、光通信、光情報処理及び光インターコネクション等に用いられる光源であり、特に波長可変機能を有する波長可変レーザ光源、及びその駆動方法に利用することができる。 The present invention is a light source used for optical communication, optical information processing, optical interconnection, and the like, and can be used for a wavelength variable laser light source having a wavelength variable function and a driving method thereof.
１　波長可変共振器、２、３　リング型共振器、１０　基板、
１１　第１の半導体光増幅器、１２　第２の半導体光増幅器、
１３、１４　高反射膜、１５　入力光導波路、
１６　３ｄＢ合分波器、１７　出力光導波路、
１８　誘電体多層膜、１９、２０　光導波路、
２１　第１のリング型光導波路、２２　第２のリング型光導波路、
２３、２４　ヒータ、３１　第１のリング型光導波路、
３２　第２のリング型光導波路、３３　第３のリング型光導波路、
３４、３５、３６　ヒータ、３７、３８、３９　光導波路、
４１　共振経路、４２　非共振経路、
４３　共振経路、４４　非共振経路、
５１　ヒータ、５２　光スイッチ、
６１　共振経路、６２　非共振経路、
６３　共振経路、６４　非共振経路、
８１　共振経路、８２　非共振経路、
８３　共振経路、８４　非共振経路、
１１１　半導体光増幅器、１１２　光変調器、
１１３　光反射膜、１１４　反射防止膜、
１１５、１１６　入力光導波路、１１７　３ｄＢ合分波器、
１１８、１１９　出力光導波路、１２０　リング型共振器、
１２１、１２２　リング型光導波路、１２３、１２４　ヒータ、
１２５　光導波路、１３１　光合分波器、
１３２、１３３　出力光導波路、１３４、１３５　出力光導波路端、
１５０　光スイッチ、１５１、１５２　入力光導波路、
１５３　３ｄＢ合分波器、１５４、１５５　光導波路、
１５６　位相シフター、１５７　３ｄＢ合分波器、
１５８、１５９　出力光導波路、１６０　出力光導波路端 1 wavelength tunable resonator, 2, 3 ring resonator, 10 substrate,
11 first semiconductor optical amplifier, 12 second semiconductor optical amplifier,
13, 14 highly reflective film, 15 input optical waveguide,
16 3 dB multiplexer / demultiplexer, 17 output optical waveguide,
18 Dielectric multilayer film, 19, 20 Optical waveguide,
21 first ring-type optical waveguide, 22 second ring-type optical waveguide,
23, 24 heater, 31 first ring type optical waveguide,
32 second ring-type optical waveguide, 33 third ring-type optical waveguide,
34, 35, 36 heater, 37, 38, 39 optical waveguide,
41 resonant path, 42 non-resonant path,
43 resonant path, 44 non-resonant path,
51 heater, 52 optical switch,
61 resonant path, 62 non-resonant path,
63 resonant path, 64 non-resonant path,
81 resonant path, 82 non-resonant path,
83 resonant path, 84 non-resonant path,
111 semiconductor optical amplifier, 112 optical modulator,
113 light reflection film, 114 antireflection film,
115, 116 input optical waveguide, 117 3 dB multiplexer / demultiplexer,
118, 119 output optical waveguide, 120 ring resonator,
121, 122 ring type optical waveguide, 123, 124 heater,
125 optical waveguide, 131 optical multiplexer / demultiplexer,
132, 133 output optical waveguide, 134, 135 output optical waveguide end,
150 optical switch, 151, 152 input optical waveguide,
153 3 dB multiplexer / demultiplexer, 154, 155 optical waveguide,
156 phase shifter, 157 3 dB multiplexer / demultiplexer,
158, 159 output optical waveguide, 160 output optical waveguide end

Claims (16)

  1. 　第１入力ポート、第２入力ポート、及び出力ポートを有し、透過光強度の波長スペクトルピークを移動させることのできる波長可変フィルターと、
    　一端が前記第１入力ポートと光学的に接続された第１光増幅器と、
    　一端が前記第２入力ポートと光学的に接続され、前記第１光増幅器と利得波長スペクトルの異なる第２光増幅器と、
    　前記出力ポートの端面に設けられ、所定の反射率及び透過率を有する光学ミラーと、を備える波長可変レーザ光源。     A tunable filter having a first input port, a second input port, and an output port, and capable of moving a wavelength spectrum peak of transmitted light intensity;
    A first optical amplifier having one end optically connected to the first input port;
    A second optical amplifier having one end optically connected to the second input port and having a gain wavelength spectrum different from that of the first optical amplifier;
    A wavelength tunable laser light source comprising: an optical mirror provided on an end face of the output port and having a predetermined reflectance and transmittance.
  2. 　前記第１光増幅器及び前記第２光増幅器は、互いに利得ピーク波長の異なる半導体光増幅器であり、平面光回路によって構成された前記波長可変フィルターと同一基板上に集積されている請求項１に記載の波長可変レーザ光源。 The first optical amplifier and the second optical amplifier are semiconductor optical amplifiers having different gain peak wavelengths, and are integrated on the same substrate as the wavelength tunable filter configured by a planar optical circuit. Tunable laser light source.
  3. 　前記第１光増幅器、前記第２光増幅器、及び前記波長可変フィルターは、化合物半導体材料により形成され、同一基板上にモノリシック集積されている請求項２に記載の波長可変レーザ光源。 3. The wavelength tunable laser light source according to claim 2, wherein the first optical amplifier, the second optical amplifier, and the wavelength tunable filter are formed of a compound semiconductor material and monolithically integrated on the same substrate.
  4. 　前記波長可変フィルターは、
    　周囲長の異なる２つのリング型光導波路が近接して縦列配置されたリング型共振器と、
    　２つの入力ポート端と１つの出力ポート端とを有する合分波器と、を備え、
    　前記合分波器の２つの入力ポート端は、前記リング型共振器の一方のリング型光導波路に光学結合するように配置された光導波路で互いに接続され、
    　前記合分波器の出力ポート端には、所定の反射率を有する半ミラーが備えられ、
    　前記第１光増幅器及び前記第２光増幅器のそれぞれの一端は、前記リング型共振器の他方のリング型光導波路に光学結合するように配置された光導波路で互いに接続され、
    　前記第１光増幅器及び前記第２光増幅器のそれぞれの他端には、高反射ミラーが備えられ、
    　導波路の屈折率を変化させて波長特性をチューニングする電極構造が、前記リング型共振器の２つのリング型光導波路のそれぞれの近傍に設けられていることを特徴とする請求項１乃至３のいずれか１項に記載の波長可変レーザ光源。     The wavelength tunable filter is
    A ring resonator in which two ring optical waveguides having different perimeters are arranged in close proximity to each other;
    A multiplexer / demultiplexer having two input port ends and one output port end,
    Two input port ends of the multiplexer / demultiplexer are connected to each other by an optical waveguide disposed so as to be optically coupled to one ring optical waveguide of the ring resonator,
    A half mirror having a predetermined reflectivity is provided at the output port end of the multiplexer / demultiplexer,
    One end of each of the first optical amplifier and the second optical amplifier is connected to each other by an optical waveguide disposed so as to be optically coupled to the other ring optical waveguide of the ring resonator,
    High reflection mirrors are provided at the other ends of the first optical amplifier and the second optical amplifier,
    The electrode structure for tuning the wavelength characteristic by changing the refractive index of the waveguide is provided in the vicinity of each of the two ring optical waveguides of the ring resonator. The wavelength tunable laser light source according to any one of the above.
  5. 　前記波長可変フィルターは、
    　第１リング型光導波路と、前記第１リング型光導波路と直線状の光導波路を介して互いに対称な位置で光学的に接続された、前記第１リング型光導波路と異なる周囲長の第２リング型光導波路及び第３リング型光導波路と、を有するリング型共振器と、
    　２つの入力ポート端と１つの出力ポート端とを有する合分波器と、を備え、
    　前記合分波器の一方の入力ポート端には、前記第２リング型光導波路と光学的に結合するように近接配置された光導波路の一端が光学的に接続され、
    　前記合分波器の他方の入力ポート端には、前記第３リング型光導波路と光学的に結合するように近接配置された光導波路の一端が光学的に接続され、
    　前記合分波器の出力ポート端には、所定の反射率を有する半ミラーが備えられ、
    　前記第１光増幅器及び前記第２光増幅器のそれぞれの一端は、前記第１リング型光導波路に光学結合するように配置された光導波路で互いに接続され、
    　前記第１光増幅器及び前記第２光増幅器のそれぞれの他端には、高反射ミラーが備えられ、
    　導波路の屈折率を変化させて波長特性をチューニングする電極構造が、前記第１リング型光導波路、前記第２リング型光導波路、及び前記第３リング型光導波路のそれぞれの近傍に設けられていることを特徴とする請求項１乃至３のいずれか１項に記載の波長可変レーザ光源。     The wavelength tunable filter is
    A second ring-type optical waveguide and a second peripheral length different from that of the first ring-type optical waveguide, optically connected to each other at positions symmetrical to each other via the first ring-type optical waveguide and the linear optical waveguide. A ring resonator having a ring optical waveguide and a third ring optical waveguide;
    A multiplexer / demultiplexer having two input port ends and one output port end,
    One input port end of the multiplexer / demultiplexer is optically connected to one end of an optical waveguide that is disposed in close proximity so as to be optically coupled to the second ring optical waveguide,
    The other input port end of the multiplexer / demultiplexer is optically connected to one end of an optical waveguide disposed in close proximity so as to be optically coupled to the third ring optical waveguide,
    A half mirror having a predetermined reflectivity is provided at the output port end of the multiplexer / demultiplexer,
    One end of each of the first optical amplifier and the second optical amplifier is connected to each other by an optical waveguide disposed so as to be optically coupled to the first ring optical waveguide,
    High reflection mirrors are provided at the other ends of the first optical amplifier and the second optical amplifier,
    An electrode structure for tuning a wavelength characteristic by changing a refractive index of the waveguide is provided in the vicinity of each of the first ring optical waveguide, the second ring optical waveguide, and the third ring optical waveguide. The tunable laser light source according to claim 1, wherein the tunable laser light source is a light source.
  6. 　前記波長可変フィルターは、
    　周囲長の異なる２つのリング型光導波路が近接して縦列配置されたリング型共振器と、
    　２つの入力ポート端と２つの出力ポート端とを有する合分波器と、を備え、
    　前記合分波器の２つの入力ポート端は、前記リング型共振器の一方のリング型光導波路に光学結合するように配置された光導波路で互いに接続され、
    　前記合分波器の一方の出力ポート端には、高反射ミラーが備えられ、
    　前記合分波器の他方の出力ポート端には、無反射処理が施され、
    　前記第１光増幅器及び前記第２光増幅器のそれぞれの一端は、前記リング型共振器の他方のリング型光導波路に光学結合するように配置された光導波路で互いに接続され、
    　前記第１光増幅器及び前記第２光増幅器のそれぞれの他端には、高反射ミラーが備えられ、
    　導波路の屈折率を変化させて波長特性をチューニングする電極構造が、前記リング型共振器の２つのリング型光導波路のそれぞれの近傍に設けられていることを特徴とする請求項１乃至３のいずれか１項に記載の波長可変レーザ光源。     The wavelength tunable filter is
    A ring resonator in which two ring optical waveguides having different perimeters are arranged in close proximity to each other;
    A multiplexer / demultiplexer having two input port ends and two output port ends,
    Two input port ends of the multiplexer / demultiplexer are connected to each other by an optical waveguide disposed so as to be optically coupled to one ring optical waveguide of the ring resonator,
    A high reflection mirror is provided at one output port end of the multiplexer / demultiplexer,
    The other output port end of the multiplexer / demultiplexer is subjected to antireflection treatment,
    One end of each of the first optical amplifier and the second optical amplifier is connected to each other by an optical waveguide disposed so as to be optically coupled to the other ring optical waveguide of the ring resonator,
    High reflection mirrors are provided at the other ends of the first optical amplifier and the second optical amplifier,
    The electrode structure for tuning the wavelength characteristic by changing the refractive index of the waveguide is provided in the vicinity of each of the two ring optical waveguides of the ring resonator. The wavelength tunable laser light source according to any one of the above.
  7. 　前記波長可変フィルターは、
    　第１リング型光導波路と、前記第１リング型光導波路と直線状の光導波路を介して互いに対称な位置で光学的に接続された、前記第１リング型光導波路と異なる周囲長の第２リング型光導波路及び第３リング型光導波路と、を有するリング型共振器と、
    　２つの入力ポート端と２つの出力ポート端とを有する合分波器と、を備え、
    　前記合分波器の一方の入力ポート端には、前記第２リング型光導波路と光学的に結合するように近接配置された光導波路の一端が光学的に接続され、
    　前記合分波器の他方の入力ポート端には、前記第３リング型光導波路と光学的に結合するように近接配置された光導波路の一端が光学的に接続され、
    　前記合分波器の一方の出力ポート端には、高反射ミラーが具備され、
    　前記合分波器の他方の出力ポート端には、無反射処理が施され、
    　前記第１光増幅器及び前記第２光増幅器のそれぞれの一端は、前記第１リング型光導波路に光学結合するように配置された光導波路で互いに接続され、
    　前記第１光増幅器及び前記第２光増幅器のそれぞれの他端には、高反射ミラーが備えられ、
    　導波路の屈折率を変化させて波長特性をチューニングする電極構造が、前記第１リング型光導波路、前記第２リング型光導波路、及び前記第３リング型光導波路のそれぞれの近傍に設けられていることを特徴とする請求項１乃至３のいずれか１項に記載の波長可変レーザ光源。     The wavelength tunable filter is
    A second ring-type optical waveguide and a second peripheral length different from that of the first ring-type optical waveguide, optically connected to each other at positions symmetrical to each other via the first ring-type optical waveguide and the linear optical waveguide. A ring resonator having a ring optical waveguide and a third ring optical waveguide;
    A multiplexer / demultiplexer having two input port ends and two output port ends,
    One input port end of the multiplexer / demultiplexer is optically connected to one end of an optical waveguide that is disposed in close proximity so as to be optically coupled to the second ring optical waveguide,
    The other input port end of the multiplexer / demultiplexer is optically connected to one end of an optical waveguide disposed in close proximity so as to be optically coupled to the third ring optical waveguide,
    A high reflection mirror is provided at one output port end of the multiplexer / demultiplexer,
    The other output port end of the multiplexer / demultiplexer is subjected to antireflection treatment,
    One end of each of the first optical amplifier and the second optical amplifier is connected to each other by an optical waveguide disposed so as to be optically coupled to the first ring optical waveguide,
    High reflection mirrors are provided at the other ends of the first optical amplifier and the second optical amplifier,
    An electrode structure for tuning a wavelength characteristic by changing a refractive index of the waveguide is provided in the vicinity of each of the first ring optical waveguide, the second ring optical waveguide, and the third ring optical waveguide. The tunable laser light source according to claim 1, wherein the tunable laser light source is a light source.
  8. 　前記合分波器の一方の出力ポート端に備えられた前記高反射ミラーは、１つの入力ポート端と、相互に接続された２つの出力ポート端と、を有する別の合分波器によって構成された閉ループ状の導波路からなるループミラーであることを特徴とする請求項６又は７に記載の波長可変レーザ光源。 The high reflection mirror provided at one output port end of the multiplexer / demultiplexer is constituted by another multiplexer / demultiplexer having one input port end and two output port ends connected to each other. 8. The tunable laser light source according to claim 6, wherein the tunable laser light source is a loop mirror made of a closed loop-shaped waveguide.
  9. 　前記波長可変フィルターは、
    　周囲長の異なる２つのリング型光導波路が光導波路を介して互いに光学接続されたリング型共振器と、
    　２つの入力ポート端と２つの出力ポート端とを有する合分波器と、を備え、
    　前記合分波器の２つの出力ポート端のそれぞれに、前記リング型共振器の２つのリング型光導波路のそれぞれが光学結合するように近接して配置され、
    　前記リング型共振器の２つのリング型光導波路を光学接続する前記光導波路の一部に、光波パワーを取り出す為の光導波路が光学結合するように近接して配置され、
    　前記合分波器の２つの入力ポート端には、前記第１光増幅器及び前記第２光増幅器のそれぞれの一端が光学的に接続され、
    　前記第１光増幅器及び前記第２光増幅器のそれぞれの他端には、高反射ミラーが備えられ、
    　光導波路の屈折率を変化させて波長特性をチューニングする電極構造が、前記リング型共振器の２つのリング型光導波路のそれぞれの近傍に設けられていることを特徴とする請求項１乃至３のいずれか１項に記載の波長可変レーザ光源。     The wavelength tunable filter is
    A ring resonator in which two ring optical waveguides having different perimeters are optically connected to each other via the optical waveguide;
    A multiplexer / demultiplexer having two input port ends and two output port ends,
    The two output port ends of the multiplexer / demultiplexer are arranged close to each other so that the two ring optical waveguides of the ring resonator are optically coupled,
    A portion of the optical waveguide that optically connects the two ring-type optical waveguides of the ring-type resonator, is disposed close to the optical waveguide for taking out the light wave power so as to be optically coupled;
    One end of each of the first optical amplifier and the second optical amplifier is optically connected to two input port ends of the multiplexer / demultiplexer,
    High reflection mirrors are provided at the other ends of the first optical amplifier and the second optical amplifier,
    The electrode structure for tuning the wavelength characteristic by changing the refractive index of the optical waveguide is provided in the vicinity of each of the two ring optical waveguides of the ring resonator. The wavelength tunable laser light source according to any one of the above.
  10. 　前記波長可変フィルターは、
    　周囲長の異なる２つのリング型光導波路が近接して縦列配置されたリング型共振器と、
    　２つの入力ポート端と２つの出力ポート端とを有する光スイッチと、を備え、
    　前記光スイッチの２つの入力ポート端は、前記リング型共振器の一方のリング型光導波路に光学結合するように配置された光導波路で互いに接続され、
    　前記光スイッチの２つ出力ポート端のうち、少なくとも一方には、所定の反射率を有する半ミラーが備えられ、
    　前記第１光増幅器及び前記第２光増幅器のそれぞれの一端は、前記リング型共振器の他方のリング型光導波路に光学結合するように配置された光導波路で互いに接続され、
    　前記第１光増幅器及び前記第２光増幅器のそれぞれの他端には、高反射ミラーが備えられ、
    　導波路の屈折率を変化させて波長特性をチューニングする電極構造が、前記リング型共振器の２つのリング型光導波路のそれぞれの近傍に設けられていることを特徴とする請求項１乃至３のいずれか１項に記載の波長可変レーザ光源。     The wavelength tunable filter is
    A ring resonator in which two ring optical waveguides having different perimeters are arranged in close proximity to each other;
    An optical switch having two input port ends and two output port ends,
    Two input port ends of the optical switch are connected to each other by an optical waveguide arranged so as to be optically coupled to one ring optical waveguide of the ring resonator,
    At least one of the two output port ends of the optical switch is provided with a half mirror having a predetermined reflectance.
    One end of each of the first optical amplifier and the second optical amplifier is connected to each other by an optical waveguide disposed so as to be optically coupled to the other ring optical waveguide of the ring resonator,
    High reflection mirrors are provided at the other ends of the first optical amplifier and the second optical amplifier,
    The electrode structure for tuning the wavelength characteristic by changing the refractive index of the waveguide is provided in the vicinity of each of the two ring optical waveguides of the ring resonator. The wavelength tunable laser light source according to any one of the above.
  11. 　前記波長可変フィルターは、
    　第１リング型光導波路と、前記第１リング型光導波路と直線状の光導波路を介して互いに対称な位置で光学的に接続された、前記第１リング型光導波路と異なる周囲長の第２リング型光導波路及び第３リング型光導波路と、を有するリング型共振器と、
    　２つの入力ポート端と２つの出力ポート端とを有する光スイッチと、を備え、
    　前記光スイッチの一方の入力ポート端には、前記第２リング型光導波路と光学的に結合するように近接配置された光導波路の一端が光学的に接続され、
    　前記光スイッチの他方の入力ポート端には、前記第３リング型光導波路と光学的に結合するように近接配置された光導波路の一端が光学的に接続され、
    　前記光スイッチの２つの出力ポート端のうち、少なくとも一方には、所定の反射率を有する半ミラーが備えられ、
    　前記第１光増幅器及び前記第２光増幅器のそれぞれの一端は、前記第１リング型光導波路に光学結合するように配置された光導波路で互いに接続され、
    　前記第１光増幅器及び前記第２光増幅器のそれぞれの他端には、高反射ミラーが備えられ、
    　導波路の屈折率を変化させて波長特性をチューニングする電極構造が、前記第１リング型光導波路、前記第２リング型光導波路、及び前記第３リング型光導波路のそれぞれの近傍に設けられていることを特徴とする請求項１乃至３のいずれか１項に記載の波長可変レーザ光源。     The wavelength tunable filter is
    A second ring-type optical waveguide and a second peripheral length different from that of the first ring-type optical waveguide, optically connected to each other at positions symmetrical to each other via the first ring-type optical waveguide and the linear optical waveguide. A ring resonator having a ring optical waveguide and a third ring optical waveguide;
    An optical switch having two input port ends and two output port ends,
    One input port end of the optical switch is optically connected to one end of an optical waveguide that is disposed in close proximity so as to be optically coupled to the second ring optical waveguide,
    The other input port end of the optical switch is optically connected to one end of an optical waveguide that is disposed in close proximity so as to be optically coupled to the third ring optical waveguide,
    At least one of the two output port ends of the optical switch is provided with a half mirror having a predetermined reflectance.
    One end of each of the first optical amplifier and the second optical amplifier is connected to each other by an optical waveguide disposed so as to be optically coupled to the first ring optical waveguide,
    High reflection mirrors are provided at the other ends of the first optical amplifier and the second optical amplifier,
    An electrode structure for tuning a wavelength characteristic by changing a refractive index of the waveguide is provided in the vicinity of each of the first ring optical waveguide, the second ring optical waveguide, and the third ring optical waveguide. The tunable laser light source according to claim 1, wherein the tunable laser light source is a light source.
  12. 　前記波長可変フィルターは、
    　周囲長の異なる２つのリング型光導波路が光導波路を介して互いに光学接続されたリング型共振器と、
    　２つの入力ポート端と２つの出力ポート端とを有する合分波器と、
    　２つの入力ポート端と２つの出力ポート端とを有する光スイッチと、を備え、
    　前記合分波器の２つの出力ポート端のそれぞれに、前記リング型共振器の２つのリング型光導波路のそれぞれが光学結合するように近接して配置され、
    　前記合分波器の２つの入力ポート端には、前記第１光増幅器及び前記第２光増幅器のそれぞれの一端が光学的に接続され、
    　前記第１光増幅器および前記第２光増幅器のそれぞれの他端には、前記光スイッチの２つの入力ポート端がそれぞれ光学的に接続され、
    　前記光スイッチの２つの出力ポート端のうち、少なくとも一方端には、所定の反射率を有する半ミラーが備えられ、
    　光導波路の屈折率を変化させて波長特性をチューニングする電極構造が、前記リング型共振器の２つのリング型光導波路のそれぞれの近傍に設けられていることを特徴とする請求項１乃至３のいずれか１項に記載の波長可変レーザ光源。     The wavelength tunable filter is
    A ring resonator in which two ring optical waveguides having different perimeters are optically connected to each other via the optical waveguide;
    A multiplexer / demultiplexer having two input port ends and two output port ends;
    An optical switch having two input port ends and two output port ends,
    The two output port ends of the multiplexer / demultiplexer are arranged close to each other so that the two ring optical waveguides of the ring resonator are optically coupled,
    One end of each of the first optical amplifier and the second optical amplifier is optically connected to two input port ends of the multiplexer / demultiplexer,
    Two input port ends of the optical switch are optically connected to the other ends of the first optical amplifier and the second optical amplifier,
    At least one of the two output port ends of the optical switch is provided with a half mirror having a predetermined reflectance,
    The electrode structure for tuning the wavelength characteristic by changing the refractive index of the optical waveguide is provided in the vicinity of each of the two ring optical waveguides of the ring resonator. The wavelength tunable laser light source according to any one of the above.
  13. 　請求項１乃至９のいずれか１項に記載の波長可変レーザ光源の駆動方法であって、
    　所望する波長に応じて、前記第１光増幅器及び前記第２光増幅器のうちの一方に電流注入を行うと同時に、他方には電流注入を行わないことを特徴とする波長可変レーザ光源の駆動方法。     A method of driving a wavelength tunable laser light source according to any one of claims 1 to 9,
    A method of driving a wavelength tunable laser light source, wherein current is injected into one of the first optical amplifier and the second optical amplifier according to a desired wavelength, and no current is injected into the other. .
  14. 　請求項１０乃至１２のいずれか１項に記載の波長可変レーザ光源の駆動方法であって、
    　所望する波長に応じて、前記第１光増幅器及び前記第２光増幅器のうちの一方に電流注入を行うと同時に、他方には電流注入を行わず、
    　前記半ミラーの設けられた前記出力ポート端で所望する大きさの光出力が得られるよう、電流が注入された側の光増幅器に合わせて前記光スイッチの経路を切り換えることを特徴とする波長可変レーザ光源の駆動方法。     A driving method of a wavelength tunable laser light source according to any one of claims 10 to 12,
    According to a desired wavelength, current is injected into one of the first optical amplifier and the second optical amplifier, and at the same time, no current is injected into the other
    Wavelength variable, characterized in that the path of the optical switch is switched in accordance with the optical amplifier on the side where current is injected so that a desired optical output can be obtained at the output port end provided with the half mirror Driving method of laser light source.
  15. 　透過光強度の波長スペクトルピークを移動させることのできる波長可変フィルターと、
    　前記波長可変フィルターにそれぞれ並列接続された光増幅器及び光変調器と、を備え、
    　前記光変調器が、前記波長可変フィルター及び前記光増幅器と同一基板上に集積されている波長可変レーザ光源。     A tunable filter capable of moving the wavelength spectrum peak of transmitted light intensity;
    An optical amplifier and an optical modulator respectively connected in parallel to the wavelength tunable filter,
    A wavelength tunable laser light source in which the optical modulator is integrated on the same substrate as the wavelength tunable filter and the optical amplifier.
  16. 　前記波長可変フィルターは、
    　周囲長の異なる２つのリング型光導波路が光導波路を介して互いに光学接続されたリング型共振器と、
    　２つの入力ポート端と２つの出力ポート端とを有する合分波器と、を備え、
    　前記合分波器の２つの出力ポート端のそれぞれに、前記リング型共振器の２つのリング型光導波路のそれぞれが光学結合するように近接して配置され、
    　前記合分波器の２つの入力ポート端の一方には前記光増幅器の一端が光学的に接続され、他方には前記光変調器の一端が光学的に接続され、
    　前記光増幅器の他端には、高反射ミラーが備えられ、
    　前記光変調器の他端には、反射防止膜が施され、
    　光導波路の屈折率を変化させて波長特性をチューニングする電極構造が、前記リング型共振器の２つのリング型光導波路のそれぞれの近傍に設けられていることを特徴とする請求項１５に記載の波長可変レーザ光源。     The wavelength tunable filter is
    A ring resonator in which two ring optical waveguides having different perimeters are optically connected to each other via the optical waveguide;
    A multiplexer / demultiplexer having two input port ends and two output port ends,
    The two output port ends of the multiplexer / demultiplexer are arranged close to each other so that the two ring optical waveguides of the ring resonator are optically coupled,
    One end of the optical amplifier is optically connected to one of the two input port ends of the multiplexer / demultiplexer, and one end of the optical modulator is optically connected to the other.
    The other end of the optical amplifier is provided with a high reflection mirror,
    The other end of the light modulator is provided with an antireflection film,
    The electrode structure for tuning the wavelength characteristic by changing the refractive index of the optical waveguide is provided in the vicinity of each of the two ring optical waveguides of the ring resonator. Tunable laser light source.
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