KR20130012835A - Light source apparatus using ring resonator, optical communication system and method for the same - Google Patents

Abstract

PURPOSE: A light source device using a ring resonator, and an optical communications system for the same and a method thereof are provided to reduce the width of a line of incident light source, in order to reduce optical power loss and to improve the quality of an optical signal for a wavelength independent optical transceiver. CONSTITUTION: A BLS(Broadband Light Source)(101) forms broadband light. At least one ring resonator(103) receives the broadband light. The ring resonator transmits broadband light of which width is fixed to an output port. The fixed width of a line coincides with a resonant wavelength at the intervals of an FSR(Free Spectral Range). The ring resonator reduces changes in refractive index caused by temperature change, by using a thermostat or materials with different temperature coefficients of refractive index.

Description

Light source device using ring resonator and optical communication system and method therefor {LIGHT SOURCE APPARATUS USING RING RESONATOR, OPTICAL COMMUNICATION SYSTEM AND METHOD FOR THE SAME}

The present invention relates to the field of optical communication, and more particularly, to a light source device using a ring resonator, and an optical communication system and method therefor.

An optical communication system using a wavelength division multiplexing access (WDMA) is a method of transmitting and receiving optical signals of different wavelengths output from a plurality of optical transceivers through a single optical fiber using a wavelength division multiplexing device. The wavelength division multiple access can transmit a large amount of data at the same time, thereby increasing the bandwidth between the transmission intervals, and the rental cost of the optical line by transmitting data using one optical fiber instead of using multiple optical fibers And there is an advantage to save the maintenance cost.

In the conventional wavelength division multiplex connection, the wavelength is fixed for each connection port according to the number of connection ports of the wavelength division multiplexing device composed of an optical thin film filter (TFF) or an arrayed waveguide grating (AWG). Since a large number of optical transceivers are required, a system operator has difficulty in securing and storing a plurality of optical transceivers having fixed wavelengths for each access port in accordance with system expansion or increase in subscribers.

In order to solve this problem, Korean Patent Registration No. 10-0325687 and "Optical Signal Transmitter" named "Light source for wavelength division multiplex optical communication using a Fabry-Perot laser diode immersed in injected non-coherent light" U.S. Patent Publication No. 2003/007207, entitled “Color less or Color free” wavelength division multiple access, which automatically determines the optical output wavelength of an optical transceiver at a wavelength assigned to a connection port of an optical transceiver and a wavelength division multiplexing device. This has been proposed. According to the proposal, non-coherent broadband light is passed through a diffraction grating with an optical thin film filter or an arrayed waveguide, and then injected into a Fabric-Perot Laser Diode (FP LD), a Semiconductor Optical Amplifier (SOA), or a Reflective Semiconductor Optical Amplifier (RSOA). An optical signal wavelength equal to the allocated wavelength is output in accordance with the connection port of the wavelength division multiplexing device.

Wavelength-independent wavelength division multiplexing optical communication system has the output light of broadband light source (BLS) of optical line terminal (OLT) located in central office (CO). Passes through a passband allocated for each connection port of a wavelength division multiplexing device composed of a plurality of thin film filters (TFF) or an arrayed waveguide grating (AWG). The broadband light source passing through the access port of the wavelength division multiplexer is injected into a wavelength independent optical transceiver composed of a light source of FP LD, SOA or RSOA located in an optical network terminal (ONT). It outputs an optical signal that matches the wavelength of the connection port, and compared to the conventional method of using an optical transceiver having a fixed wavelength for each connection port of the wavelength division multiplexing device, a single irrespective of the connection port of the wavelength division multiplexing device. An optical transceiver may be used to implement a wavelength division multiple access optical communication system.

However, when the broadband light source passes a passband for each connection port of the wavelength division multiplexing device, the spectrum of the remaining broadband light sources except for the broadband light source that has passed through the passband for each connection port of the wavelength division multiplexing device is used as a wavelength division multiplexing device. As they are not passed through, they are cut off, resulting in an optical increase in Relative Intensity Noise (RIN). In addition, the broadband light source passed through the wavelength division multiplexer is injected into a wavelength independent optical transceiver composed of FP LD, SOA, or RSOA light source, and the spectrum of the output optical signal is wider than the line width of the injected broadband light source and passes through the wavelength division multiplexer. When the spectrum is transmitted by the wavelength independent optical transceiver, the spectral region where the spectrum of the optical output signal of the wavelength-division multiplexer is wider than the passband of the connection port of the wavelength division multiplexer does not pass through the wavelength division multiplexer. Increasing the intensity noise affects the performance of the wavelength division multiple access optical communication system using the wavelength independent optical transmitter, thereby limiting the transmission speed and the transmission distance.

Korean Patent Publication No. 10-2006-0014528 (published Feb. 16, 2006) Korean Patent Publication No. 10-2010-0078909 (published Jul. 8, 2010)

The present invention provides a light source device using a ring resonator, and an optical communication system and method therefor.

The light source device of the present invention comprises: a light source for forming broadband light; And at least one ring resonator receiving the wideband light and outputting wideband light having a predetermined line width corresponding to the resonant wavelength at a free spectral range (FSR) interval to an output port.

In addition, the light source device of the present invention, a light source for forming broadband light; And at least one ring resonator receiving the wideband light and outputting wideband light of a wavelength other than the wideband light coinciding with the resonant wavelength at a free spectral range (FSR) interval.

In addition, the optical communication system of the present invention, a light source device for receiving a wideband light and outputs a plurality of light spectrum having a predetermined line width corresponding to the resonant wavelength in the free spectral range (FSR) interval; An optical filter having a predetermined channel spacing and filtering the plurality of light spectrums; And an optical transceiver for receiving the filtered light spectrum.

In addition, the optical communication system of the present invention receives a wide band of light and passes through a plurality of light spectrums having a predetermined line width corresponding to a wavelength excluding a wide band of light corresponding to a resonant wavelength at a free spectral range (FSR) interval. A light source device for outputting; An optical filter having a predetermined channel spacing and filtering the plurality of light spectrums; And an optical transceiver for receiving the filtered light spectrum.

In addition, the optical communication method of the present invention comprises the steps of: a) receiving a wideband light and outputting a plurality of light spectrums having a predetermined line width corresponding to the resonant wavelength at a free spectral range (FSR) interval; b) filtering the plurality of light spectra; And c) receiving the filtered light spectrum.

According to the present invention, the wavelength-independent optical transceiver is used to reduce the optical output loss and improve the optical signal quality of the wavelength-independent optical transceiver, which is suitable for a wavelength division multiple access optical communication system capable of high-speed data transmission and long-distance transmission. By reducing the line width of the light source, it reduces the relative intensity noise (RIN) caused by spectrum cutting while passing through the wavelength division multiplexing device, and reduces the line width of the light output signal of the wavelength independent optical transmitter according to the line width of the injected light source. Reducing the relative intensity noise (RIN) and light output loss of the wavelength independent optical transceiver generated by spectral truncation while passing through the wavelength division multiplexing device, and also the wavelength division by the reduced line width of the optical output signal of the wavelength independent optical transceiver. Optical Signal Interference Between Adjacent Channels Passing Through Multiplexing Devices al Crosstalk) can be reduced.

1 is a schematic diagram of a wavelength independent wavelength division multiple access optical communication system using a broadband light source having a ring resonator in accordance with an embodiment of the present invention;
2 is an exemplary view showing a single ring resonator in accordance with an embodiment of the present invention.
3 is an exemplary view showing a multiple ring resonator in accordance with an embodiment of the present invention.
4 is an exemplary view showing a transmission characteristic spectrum of an output port of a single / multi-ring resonator according to an embodiment of the present invention.
5 is an exemplary view showing a transmission characteristic spectrum of a through port of a single / multiple ring resonator according to an embodiment of the present invention.
Figure 6 is an exemplary view showing a wavelength independent wavelength division multiple access optical communication system using a broadband light source including a ring resonator capable of long-distance transmission using an optical amplifier (OA) according to an embodiment of the present invention.
FIG. 7 illustrates a system using a broadband light source including a ring resonator in a WDM-PON system using an optical coupler as a broadband light source coupling device according to an embodiment of the present invention. Illustrated diagram.
8 is a broadband light source coupling device according to an embodiment of the present invention including a ring resonator in a WDM-PON system using an optical circulator and an optical filter. An illustration showing a system using a broadband light source.
9 is a flow chart showing the procedure of the optical communication method according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions will not be described in detail if they obscure the subject matter of the present invention.

One embodiment of a wavelength division multiple access optical communication system composed of a wavelength independent optical transceiver is a wavelength division multiplexing passive optical network (WDM-PON) system.

The wavelength division multiplexing passive optical subscriber network includes an optical line terminal (OLT), an optical distribution network (ODN) and an optical subscriber terminal (ONT).

The optical line termination device is located in a central base station (CO) and is composed of a plurality of wavelength independent optical transceivers, a wavelength division multiplexing device, a broadband light source, and a broadband light source combining device.

The optical distribution network consists of passive wavelength division multiplexing devices that do not require power supply, and are connected to optical line termination devices and optical subscriber devices through optical fibers. In the optical distribution network, the place where the passive wavelength division multiplexing device connected to the optical line termination device and the optical subscriber device is called a remote node (RN).

An optical subscriber device is located in a subscriber's premises or near-field and includes a wavelength independent optical transceiver.

1 is a schematic diagram of a wavelength independent wavelength division multiple access optical communication system using a broadband light source having a ring resonator according to an embodiment of the present invention.

Referring to FIG. 1, the broadband light source (BLS) 101 of the present invention is a light emitting diode (LED), an optical fiber amplifier or super light emitting diode (ASE) that outputs amplified spontaneous emission (ASE). It is possible to use one generated from any one of a super luminescent diode (SLD), and the ring resonator 103 may be implemented as a single ring or multiple rings. The broad spectrum 102 of the broadband light source 101 passes through only the resonant wavelength satisfying phase matching with the ring resonator 103 to form a new broadband light source 104 having a narrow linewidth spectrum in the same wide band as the broadband light source. . The broadband light source 104 passing through the ring resonator 103 is an arrayed waveguide grating (AWG) or an optical thin film filter that performs a filter function through the optical circulator 105 and the optical fiber 106. (TFF; Thin Film Filter) 107 is passed through. In one embodiment, the spectral linewidth 104 of the broadband light source passing through the ring resonator 103 may be equal to or narrower than the passband of the AWG / TFF 107. The wavelength of the light output of the wavelength independent optical transceiver is determined by the wavelengths allocated for the connection ports of the broadband light source 104 and the AWG / TFF 107 passing through the ring resonator 103. The broadband light source 104 passing through the ring resonator 103 having a narrower than the passband allocated for each connection port of the AWG / TFF 107 is optically low relative intensity noise (RIN) even though it passes through the AWG / TFF 107. It has Relative Intensity Noise and is injected into a wavelength independent optical transceiver 108 having a Fabric-Perot Laser Diode (FP LD), a Reflective Semiconductor Optical Amplifier (RSAA), or a Semiconductor Optical Amplifier (SOA) as a light source. The light output spectrum 111 of the wavelength independent optical transceiver 108 is wavelength locked or amplified by the broadband light source 104 passing through the injected narrow linewidth ring resonator 103 and passes through the AWG / TFF 107. Even if the optical output spectrum 109 of the wavelength independent optical transceiver 108 narrower than the passband of the connection port of the AWG / TFF 107 does not increase the optical output loss and the relative intensity noise (RIN), The optical output spectrum 111 of the wavelength independent optical transceiver 108 causes optical crosstalk between adjacent channels to decrease as it passes through the AWG / TFF 107.

The ring resonator 103 has a free spectral range (FSR) determined by the speed "C" of the light, the refractive index "n" of the ring resonator waveguide, and the length "L" of the ring resonator, as shown in Equation 1 below. Only the resonant wavelengths determined by the ring resonator 103 of the spectrum of the broadband light source 102 input at intervals of are transmitted to the output port of the ring resonator 103.

The FRS is determined by Equation 1 to match the channel spacing between the connection ports of the wavelength division multiplexing device composed of a plurality of optical thin film filters or array waveguide diffraction gratings. On the other hand, the line width and resonance wavelength of the optical signal output from the ring resonator 103 are affected by the coupling strength of the waveguides, the size and the number of rings.

2 and 3, the ring resonators 200 and 300 may be implemented as a single ring 200 or multiple rings 300. The ring resonators 200 and 300 are composed of a first linear waveguide L1, a second linear waveguide L2, and ring waveguides R0, R1, R2, and R3, and an optical signal is input to the first linear waveguide L1. Through port (P2) through which the optical signal that does not pass through the ring waveguide (R0, R1, R2, R3) of the optical signal input to the input port (P1), the first linear waveguide (L1) The optical signal input through the input port P1 of the first linear waveguide L1 passes through the ring waveguides R0, R1, R2, and R3 and is output through the second linear waveguide L2. port) (P3).

The ring resonators 200 and 300 have only the resonant wavelength satisfying the phase matching between the first linear waveguide L1, the second linear waveguide L2, and the ring waveguides R0, R1, R2, and R3. It has a characteristic of transmitting to the output port (P3) of the, and as the through port (P2) of the optical signal input to the input port (P1) of the first linear waveguide (L1) only the remaining optical signal transmitted to the output port (P3) It has the property to pass. The bandwidth of the resonant wavelength transmitted to the output port P3 varies according to the coupling strength between the linear waveguides L1 and L2 of the ring resonators 200 and 300 and the ring waveguides R0, R1, R2, and R3. In general, as the optical coupling intensity increases, the bandwidth of the ring resonators 200 and 300 becomes wider, and when the optical coupling intensity becomes smaller, the bandwidth of the ring resonators 200 and 300 becomes smaller. In addition, as the multiple rings are used as compared to the single ring, the effective resonance length is longer, the bandwidth is smaller, the line width of the output optical signal is narrower, and the frequency chirp characteristic is improved.

As one embodiment, the ring resonators 200 and 300 may form a single coupling or multiple ring resonators by forming the optical coupling structure of the ring waveguide in a horizontal structure or a vertical structure.

As described above, the bandwidth of the output port P3 of the ring resonators 200 and 300 becomes wider or smaller according to the coupling strength of the ring resonators 200 and 300, and the bandwidth of the pass port P2 becomes wider or smaller. When the bandwidth of the output port P3 is widened, the bandwidth of the pass-through port P2 is small, and when the bandwidth of the output port P3 is reduced, the bandwidth of the through-port P2 is widened.

4 and 5 are spectrums showing the transmission characteristics of the output port and the pass port of the ring resonator according to an embodiment of the present invention. In one embodiment, the broadband light source may be configured to be used as a light source for the wavelength independent light transceiver, the light source passed through the output port of the ring resonator or the broadband light source passed through the pass port.

6 is a schematic diagram of a wavelength independent wavelength division multiple access optical communication system using a broadband light source including a ring resonator 602 further comprising an optical amplifier (OA) 603 according to an embodiment of the present invention. The broadband light source passed through the ring resonator 602 is amplified using the optical amplifier 603 to increase the intensity of the light source injected into the wavelength independent optical transceiver 607 to enable long distance transmission.

As shown in FIG. 6, an external optical amplifier 603 may be used, and the ring resonator itself may include a function of an optical amplifier by doping a gain medium such as Erbium to the waveguide of the ring resonator.

7 is a broadband light source including a ring resonator in a WDM-PON system using an optical coupler 717 as a broadband light source coupling device according to an embodiment of the present invention. -BLS, B-BLS) (715, 716) is a schematic diagram of the system.

8 is a wavelength division multiplexing passive optical subscriber network (WDM) using optical circulators 818 and 820 and optical filters 817 and 819 as a broadband light source coupling device according to an embodiment of the present invention. -PON is a schematic diagram of a system using broadband light sources (A-BLS, B-BLS) 815, 816 including ring resonators in a system.

7 and 8, the optical line terminator (OLT) 710, 810 includes a plurality of wavelength independent optical transceivers 711, 712, 713, 811, 812, 813, and a wavelength division multiplexer 714. 814, broadband light sources (A-BLS, B-BLS) 715, 716, 815, 816, broadband light source combiners 717, 817, 818, 819, 820 and multiple wavelength independent optical transceivers 711 712, 713, 811, 812, 813 and the optical fiber L10, L11, L13 connecting the wavelength division multiplexers 714, 814. The optical distribution networks 720 and 830 have wavelength split multiplexers 721 and 831 located at a remote node (RN) and optical line termination devices 710 and 810 and wavelengths located at a remote node (RN). Optical fiber L20 connecting the split multiplexers 721 and 831 and wavelength independent optical transceivers 731, 732, 733, 841, 842 and 843 of the plurality of optical subscriber devices 730 and 840. It consists of fibers L30, L31, L32. Multiple optical subscriber devices 730, 840 include wavelength independent optical transceivers 731, 732, 733, 841, 842, 843. Among the broadband light sources (A-BLS, B-BLS) 715, 716, 815, 816, the A-band broadband light sources (A-BLS) 715, 815 are provided by the optical subscriber unit (710, 810). The light source transmitted in the direction of 730 and 840 is an injection light source of the wavelength independent optical transceivers 731, 732, 733, 841, 842 and 843 of the optical subscriber device 730 and 840. Among the broadband light sources (A-BLS, B-BLS) 715, 716, 815, 816, the B-band broadband light sources (B-BLS) 716, 816 are wavelength independent in the optical line terminators 710, 810. It becomes an injection light source of the optical transceivers 711, 712, 713, 811, 812, 813. The wavelength division multiplexers 714, 721, 814, and 831 placed at the optical line termination devices 710 and 810 and the remote point RN may use a plurality of optical thin film filters or an arrayed waveguide diffraction grating.

The broadband light sources 715, 716, 815, 816 of FIGS. 7 and 8 may include broadband light sources using single ring or multiple ring resonators.

The broadband light sources 715, 716, 815, and 816 of Figs. 7 and 8 are connected to the first stage of the ring resonator through the second stage of the ring resonator input port when the multi-stage ring resonator is used, the second pass port or output It may include a broadband light source passed through the port or a broadband light source passed through the second pass port or the output port by connecting the output port of the first stage ring resonator to the input port of the second stage ring resonator.

The broadband light sources 715, 716, 815, and 816 of FIGS. 7 and 8 are broadband light sources passing through an output port or through port of the ring resonator, or passing through an output port or through port of the ring resonator. It can include a high power broadband light source made by passing a broadband light source back through the optical amplifier.

The high power broadband light source of FIGS. 7 and 8 may use a separate external optical amplifier and may include a broadband light source made by passing a ring resonator having an optical amplifier function by doping a gain medium in the waveguide of the ring resonator.

The broadband light sources 715, 716, 815, 816 of FIGS. 7 and 8 include a thermostat for reducing the difference in refractive index between the ring resonator waveguides to stably maintain the coupling strength of the ring resonator and the resonant wavelength of the ring resonator. The refractive index temperature coefficient (Temperature coefficient) may include a broadband light source made by passing through the ring resonator to reduce the refractive index change of the ring resonator according to the temperature change using different materials.

The wavelength division multiplexers 714, 721, 814, and 831 of FIGS. 7 and 8 may use a Gaussian or flat-top waveguide diffraction grating.

9 is a flow chart showing the procedure of the optical communication method according to an embodiment of the present invention. Referring to FIG. 9, first, the broadband light source 101 of the light source device forms broadband light, and the ring resonator 130 receives the broadband light to match the resonance wavelength at a free spectral range (FSR) interval. To output a plurality of light spectrum having a predetermined line width to the output port (S110). The optical filter filters a plurality of optical spectrums output from the ring resonator 130 (S120), and the optical transceiver receives the optical spectrum filtered by the optical filter (S130). On the other hand, the ring resonator 130 of the light source device outputs a plurality of light spectrums having a predetermined line width corresponding to the wavelength except for the broadband light corresponding to the resonance wavelength to the pass port.

While the above methods have been described through specific embodiments, the methods may also be implemented as computer readable code on a computer readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored. Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and may be implemented in the form of a carrier wave (for example, transmission over the Internet) . In addition, the computer-readable recording medium may be distributed over network-connected computer systems so that computer readable codes can be stored and executed in a distributed manner. In addition, functional programs, codes, and code segments for implementing the above embodiments can be easily deduced by programmers of the present invention.

Although the present invention has been described in connection with some embodiments thereof, it should be understood that various changes and modifications may be made therein without departing from the spirit and scope of the invention as understood by those skilled in the art. something to do. It is also contemplated that such variations and modifications are within the scope of the claims appended hereto.

101: broadband light source 102, 104, 109, 111: light spectrum graph
103: ring resonator 105: circulator
106: optical fiber 107: AWG / TFF
108: FP-LD / RSOA

Claims (23)

As a light source device,
A light source for forming broadband light; And
And at least one ring resonator configured to receive the broadband light and output broadband light having a predetermined line width corresponding to the resonance wavelength at a free spectral range (FSR) interval to an output port. As a light source device,
A light source for forming broadband light; And
And at least one ring resonator receiving the wideband light and outputting wideband light of a wavelength other than the wideband light coinciding with the resonant wavelength at a free spectral range (FSR) interval. The method according to claim 1 or 2,
The ring resonator,
Light source device, the temperature control device or the refractive index using a material having a different temperature coefficient, the refractive index change according to the temperature change. The method of claim 3,
And an optical amplifier configured to form high output light by using broadband light output through the output port or the pass port. 5. The method of claim 4,
The ring resonator,
And doping a gain medium in the waveguide to perform the function of the optical amplifier. The method of claim 5,
The gain medium is,
A light source device comprising erbium. The method according to claim 6,
The ring resonator,
A light source device comprising at least one ring waveguide. The method of claim 7, wherein
The ring resonator,
And forming a light coupling structure of the at least one ring waveguide into a horizontal structure or a vertical structure. The method according to claim 1 or 2,
The light source is
A light source device comprising a light emitting diode, an optical fiber amplifier or a super luminescent diode that outputs an amplitude of natural emission. As an optical communication system,
A light source device for receiving broadband light and outputting a plurality of light spectrums having a predetermined line width corresponding to a resonance wavelength at a free spectral range (FSR) interval to an output port;
An optical filter having a predetermined channel spacing and filtering the plurality of light spectrums; And
And an optical transceiver for receiving the filtered optical spectrum. As an optical communication system,
A light source device configured to receive wideband light and output a plurality of light spectrums having a predetermined line width corresponding to a wavelength excluding a wideband light corresponding to a resonant wavelength at a free spectral range (FSR) interval to a pass port;
An optical filter having a predetermined channel spacing and filtering the plurality of light spectrums; And
And an optical transceiver for receiving the filtered optical spectrum. The method according to claim 10 or 11,
The light source device,
An optical communication system in which a temperature control device or a material having a different refractive index temperature coefficient is used to reduce a change in refractive index with a change in temperature. The method of claim 12,
The light source device,
And a plurality of light spectra output through the output port or the pass port to form high output light using an optical amplifier. The method of claim 13,
The light source device,
And doping a gain medium in the waveguide to form the high power light. 15. The method of claim 14,
The gain medium is,
An optical communication system comprising Erbuim. 16. The method of claim 15,
The light source device,
At least one ring waveguide. 17. The method of claim 16,
The light source device,
And forming the optical coupling structure of the at least one ring waveguide into a horizontal structure or a vertical structure. The method according to claim 10 or 11,
The light source device,
An optical communication system comprising a light emitting diode, an optical fiber amplifier or a super luminescent diode that outputs Amplified Spontaneous Emission. The method according to claim 10 or 11,
The optical transceiver,
An optical communication system comprising a Fabric-Perot Laser Diode (FP LD), a Reflective Semiconductor Optical Amplifier (RSOA), or a Semiconductor Optical Amplifier (SOA). The method according to claim 10 or 11,
The optical filter,
An optical communication system comprising an arrayed waveguide grating or an optical thin film filter. 21. The method of claim 20,
The arrayed waveguide diffraction grating,
An optical communication system comprising a Gaussian or flat-top arrayed waveguide grating. As an optical communication method,
a) receiving wideband light and outputting a plurality of light spectra having a predetermined line width in accordance with the resonant wavelength at free spectral range (FSR) intervals;
b) filtering the plurality of light spectra; And
c) receiving the filtered light spectrum. The method of claim 22,
The step a)
Outputting a plurality of light spectrums having a predetermined line width that matches a wavelength except for broadband light that matches the resonance wavelength.

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