JP2022053241A - Optical module - Google Patents

Abstract

To provide an optical module that is suitable for high-speed modulation, and achieves low cost and suppression of optical loss.SOLUTION: An optical module comprises: a modulator that is provided with a modulation signal imparting part containing an InP-based semiconductor material and performing modulation of inputted light; and an optical integrated circuit that is optically coupled to the modulator and formed by integration of a plurality of waveguides and a plurality of optical elements which contain a silicon-based semiconductor material. The optical integrated circuit outputs to the modulator the light which is passed through any one of the waveguides or any one of the optical elements, receives modulated light which is generated such that the modulator modulates the light, and outputs the modulated light which is passed through any other one of the waveguides or any other one of the optical elements.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical module.

As an optical module used for optical communication, a configuration in which a plurality of elements are integrated is known (Patent Documents 1 and 2). Further, an optical module in which a waveguide and an optical element are integrated on a silicon substrate by utilizing a technique called silicon photonics is known. It is considered that the optical module can be mass-produced with high accuracy, low cost, and using a silicon process. The optical module may include a modulator as an optical element.

U.S. Patent Publication No. 2019/0103938 International Publication No. 2016/166971

Further speeding up is required in optical communication. However, in a modulator using silicon photonics, the speedup may be limited due to the limitation of the modulation speed. On the other hand, a modulator using an InP-based semiconductor material is considered to be able to realize a modulation rate exceeding 96 Gbd, for example, but when combined with silicon photonics, an optical misalignment due to a difference in constituent materials or the like is considered. There is a risk of optical loss due to.

The present invention has been made in view of the above, and an object of the present invention is to provide an optical module suitable for high-speed modulation and having suppressed optical loss at low cost.

One aspect of the present invention includes a modulator including an InP-based semiconductor material and having a modulation signal addition unit that modulates the input light, and a plurality of guides including a silicon-based semiconductor material which is optically coupled to the modulator. The optical integrated circuit includes a waveguide and an optical integrated circuit in which a plurality of optical elements are integrated, and the optical integrated circuit outputs light that has passed through any of the waveguides or any of the optical elements to the modulator, and the optical integrated circuit outputs the light to the modulator. An optical module in which a modulator receives modulated light generated by modulating the light and outputs the modulated light that has passed through any other of the waveguides or other of the optical elements.

The optical coupling may be made by a butt joint or an optical coupling element.

The optical coupling element may include a lens, a GRIN lens, an optical fiber, a waveguide, or a photonic wire.

The modulator may include an optical amplifier that amplifies the light input to the modulation signal addition unit or the modulation light.

The optical integrated circuit may include a lens, a light receiving element, a polarization synthesis element, or a variable light attenuation element as the optical element.

The optical integrated circuit may include, as the optical element, a light receiving element and an optical branching element that branches a part of the passing light and outputs the light to the light receiving element.

The modulator includes two modulation signal addition units as the modulation signal addition unit, and the optical integrated circuit includes a polarization synthesis element and two variable light attenuation elements as the optical elements, and the two variable light elements. The light attenuation element may attenuate the two modulated lights generated by the two modulation signal addition units, respectively, and the polarization synthesis element may perform polarization synthesis of the attenuated two modulated lights.

The optical integrated circuit may include an optical filter and an optical equalizer.

It may be provided with an optical fiber that optically couples with the optical integrated circuit.

The optical integrated circuit may include a silicon-based semiconductor material and may be integrally configured with a base including a modulator mounting unit for mounting the modulator.

The base may include an optical fiber mounting unit for mounting an optical fiber.

It may be provided with a light source that outputs light that is input to the optical integrated circuit and output to the modulator.

It may be provided with a wavelength detector for detecting the wavelength of the light output from the light source.

The wavelength detector may be integrated in the optical integrated circuit.

The optical integrated circuit may include a coherent mixer as the optical element.

The optical integrated circuit may include, as the optical element, a light receiving element that receives light output from the coherent mixer.

The modulator may be provided with a temperature control element that is in thermal contact with the periphery of the portion of the optical integrated circuit that is optically coupled to the modulator.

According to the present invention, it is possible to realize an optical module which is suitable for high-speed modulation and whose optical loss is suppressed at low cost.

FIG. 1 is a schematic diagram showing the configuration of the optical module according to the first embodiment. FIG. 2 is a schematic diagram showing the configuration of the optical module according to the second embodiment. FIG. 3 is a schematic diagram showing the configuration of the optical module according to the third embodiment. FIG. 4 is a schematic diagram showing the configuration of the optical module according to the fourth embodiment. FIG. 5 is a schematic diagram showing the configuration of the optical module according to the fifth embodiment. FIG. 6 is a schematic diagram showing the configuration of the optical module according to the sixth embodiment. FIG. 7 is a side view of a part of the optical module shown in FIG. FIG. 8 is a schematic diagram showing the configuration of the silicon platform. FIG. 9 is a schematic diagram showing the mounting state of the silicon platform shown in FIG.

Hereinafter, embodiments will be described with reference to the drawings. The present invention is not limited to this embodiment. Further, in the description of the drawings, the same or corresponding elements are appropriately designated by the same reference numerals. In addition, it should be noted that the drawings are schematic, and the relationship between the dimensions of each element, the ratio of each element, etc. may differ from the reality. Even between the drawings, there may be parts where the relationship and ratio of the dimensions are different from each other.

(Embodiment 1)
It is a schematic diagram which shows the structure of the optical module which concerns on Embodiment 1. FIG. The optical module 100 includes a wavelength variable light source 1, a modulator 2, an optical integrated circuit 3, a wavelength rocker 4, optical fibers 5, 6, and optical coupling elements 11, 12, 13, 14, and 15. There is.

The wavelength variable light source 1 includes, for example, a semiconductor laser element, and is configured so that the wavelength of the output laser light can be changed within a predetermined range within a wavelength band of, for example, 1530 nm to 1625 nm. The tunable light source 1 outputs a laser beam that is input to the optical integrated circuit 3 and output to the modulator 2.

The modulator 2 is, for example, an MZ (Machzenda) type phase modulator, and is a known one to which a modulation signal is applied from the outside and functions as an IQ modulator. The modulator 2 includes an optical branching section 2a, a modulation signal addition section 2b, 2c, and a plurality of waveguides that realize an optical connection inside the modulator 2. The optical branching unit 2a splits the light input to the modulator 2 into two. The modulated signal addition units 2b and 2c receive input of two lights branched by the optical branching unit 2a, modulate the input light to generate modulated light, and output the modulated light. The two modulated lights have linearly polarized states that are orthogonal to each other. The modulator 2 is also called an InP-based modulator, and at least the modulation signal addition units 2b and 2c include an InP-based semiconductor material.

The optical integrated circuit 3 is an optical integrated circuit in which a plurality of waveguides including a silicon-based semiconductor material and a plurality of optical elements are integrated, and is also called a SiPh (Silicon Photonics) circuit. The silicon-based semiconductor material also includes, for example, a SiGe-based semiconductor material. Further, the optical integrated circuit 3 may include an insulating layer made of silicon oxide. The plurality of waveguides realize the optical connection inside the optical integrated circuit 3. Further, the optical integrated circuit 3 includes an optical splitting element 3a, a beam splitter (BS) 3b, 3c, a variable optical Attenuator (VOA) 3d, 3e, and an optical splitting element as optical elements. 3f, 3g, Polarization Beam Combiner (PBC) 3h, optical branching element 3i, optical equalizer 3j, coherent mixer 3k, optical branching element 3l, and high-speed PD (Photo Diode) which is a light receiving element. ) 3m, a monitor PD3n, 3o, 3p, 3q, 3r which is a light receiving element, and an optical filter 3s, 3t. The functions of these optical elements will be described in detail later.

The wavelength rocker 4 is an example of a wavelength detector for detecting the wavelength of the light output from the tunable light source 1. The wavelength rocker 4 is a known one including, for example, a planar lightwave circuit (PLC) and a PD array. The PLC branches the input light into three, outputs one of them to the PD array, and has the wavelength discrimination characteristic of each of the other two, in which the transmission characteristics change substantially periodically with respect to the wavelength. After passing through each of the two filters, it is output to the PD array. The two filters consist of, for example, a ring resonator or an MZ interferometer and have different transmission wavelength characteristics from each other. The PD array is composed of three PDs arranged in an array. Each of the three PDs in the PD array receives each of the three lights output by the PLC and outputs a current signal according to the light receiving intensity. Each current signal is transmitted through a wiring pattern to an external controller and is used to detect and control the wavelength of light.

The optical fiber 5 is optically coupled to the optical integrated circuit 3 and outputs the light output from the optical integrated circuit 3 to the outside. The optical fiber 6 is optically coupled to the optical integrated circuit 3 and inputs light from the outside to the optical integrated circuit 3. The optical fibers 5 and 6 are, for example, known single-mode optical fibers for communication.

The optical coupling element 11 optically couples the wavelength tunable light source 1 and the optical integrated circuit 3. The optical coupling element 12 optically couples the modulator 2 and the optical integrated circuit 3. The optical coupling element 13 optically couples the wavelength rocker 4 and the optical integrated circuit 3. The optical coupling element 14 optically couples the optical fiber 5 and the optical integrated circuit 3. The optical coupling element 15 optically couples the optical fiber 6 and the optical integrated circuit 3. Optical coupling elements 11 to 15 include a lens, a GRIN (Gradient INdex) lens, an optical fiber, a waveguide, or a photonic wire. The photonic wire is a wire made of resin or the like to guide light. The lens is composed of a single lens or a combination of single lenses. The lens, the GRIN lens, and the waveguide may be arranged in an array, respectively, and may be configured as an array element.

Next, an example of the function of the optical module 100 will be described. In FIG. 1, the optical path of light in the optical module 100 is schematically indicated by an arrow. The waveguide provided in the wavelength variable light source 1, the modulator 2, and the optical integrated circuit 3 is configured to guide these lights with an allowable light loss, for example, the bending radius is designed to be equal to or less than the allowable bending loss. Has been done.

The tunable light source 1 outputs a linearly polarized laser beam. The optical coupling element 11 couples the laser beam from the tunable light source 1 to the waveguide of the optical integrated circuit 3.

In the optical integrated circuit 3, the optical branching element 3a passes most of the guided laser light through the waveguide of the optical integrated circuit 3 and outputs it to the beam splitter 3b, and at the same time, partially branches and outputs it to the monitor PD3n. do. The monitor PD3n outputs a current signal according to the light receiving intensity. The current signal is transmitted to an external controller through a wiring pattern and is used to monitor the output of the tunable light source 1.

The beam splitter 3b passes most of the laser light from the optical branching element 3a and outputs it to the beam splitter 3c via a waveguide, and at the same time, partially branches and outputs to a coherent mixer 3k via a waveguide. do.

The beam splitter 3c passes most of the laser light from the beam splitter 3b and outputs it to the optical coupling element 12 via the waveguide, and at the same time, partially branches and outputs to the wavelength rocker 4 via the waveguide. do.

The optical coupling element 12 couples the laser beam from the beam splitter 3c to the waveguide of the modulator 2.

In the modulator 2, the optical branching portion 2a splits the laser beam from the optical coupling element 12 into two. The modulation signal addition units 2b and 2c receive input of two laser beams branched by the optical branching unit 2a, and IQ-modulate the input laser light to generate modulated light in a linearly polarized state orthogonal to each other. Then, it is output to the optical coupling element 12 via the waveguide.

The optical coupling element 12 outputs two modulated lights from the modulator 2 to each of the variable light attenuation elements 3d and 3e via a waveguide. The variable light attenuation elements 3d and 3e attenuate the input modulated light and output them to the optical branching elements 3f and 3g via the waveguide. The amount of attenuation of the variable light attenuation elements 3d and 3e is controlled by an electric signal transmitted from an external controller through a wiring pattern.

The optical branching elements 3f and 3g pass most of the modulated light from the variable light attenuation elements 3d and 3e, respectively, and output to the polarization combining element 3h via a waveguide, and a part of the optical branching elements 3f and 3g is branched and monitored. Output to PD3o and 3p respectively. The monitors PD3o and 3p output a current signal according to the light receiving intensity. The current signal is transmitted to an external controller through the wiring pattern and is used to monitor the output of the variable light attenuation elements 3d and 3e and to control the amount of attenuation.

The polarization synthesizing element 3h polarization-synthesizes the modulated light from the optical branching elements 3f and 3g, and outputs the modulated light to the optical branching element 3i via a waveguide.

The optical branching element 3i passes most of the modulated light from the polarization synthesizing element 3h and outputs it to the optical equalizer 3j via a waveguide, and at the same time, partially branches and outputs it to the monitor PD3q. The monitor PD3q outputs a current signal according to the light receiving intensity. The current signal is transmitted to an external controller through the wiring pattern and is used for monitoring the output of the polarization synthesizing element 3h.

The optical equalizer 3j provides attenuation of predetermined spectral characteristics so that the modulated light from the optical branching element 3i has a desired shape such as spectral flatness, and is passed through a waveguide and an optical filter 3s. It is output to the optical coupling element 14, and can be easily configured on the waveguide by a lattice type optical circuit or the like. The optical equalizer 3j is described, for example, in the non-patent documents ECOC2019, Dublin, Ireland's Tu2. D. 2 and Tu3. B. It is the one disclosed in 1. Further, the optical equalizer 3j may be a known one including an LCOS (Liquid Crystal On Silicon) and a diffraction grating, but it is economically compact by forming it on a waveguide as in this configuration. It has a high effect in realizing a module.

The optical coupling element 14 couples the modulated light transmitted through the optical filter 3s to the optical fiber 5. The optical fiber 5 propagates the modulated light to the outside.

On the other hand, the optical fiber 6 propagates the signal light from the outside and outputs it to the optical coupling element 15. The optical coupling element 15 couples the signal light from the optical fiber 6 to the waveguide of the optical integrated circuit 3 via the optical filter 3t.

In the optical integrated circuit 3, the optical branching element 3l passes most of the signal light guided through the waveguide of the optical integrated circuit 3 and outputs it to the coherent mixer 3k, and at the same time, partially branches and outputs it to the monitor PD3r. do. The monitor PD3r outputs a current signal according to the light receiving intensity. The current signal is transmitted through a wiring pattern to an external controller and is used to monitor the power of the signal light.

The coherent mixer 3k includes a 90 ° optical hybrid circuit, and the signal light input from the optical branching element 3l via the waveguide and the laser beam (local emission) input from the beam splitter 3b via the waveguide. Is processed by interfering with, a processing signal light is generated, and it is output to a high-speed PD3m. The processed signal light includes Ix signal light corresponding to the I component of X polarization, Qx signal light corresponding to the Q component of X polarization, Iy signal light corresponding to the I component of Y polarization, and Q of Y polarization. There are four Qy signal lights corresponding to the components.

The high-speed PD3m has four balanced PDs, receives each of the four processed signal lights, converts them into a current signal, and outputs the light. The current signal is transmitted through the wiring pattern to the controller or a higher level controller and used for demodulation of the signal light.

The optical filters 3s and 3t have a characteristic of mainly transmitting light in a wavelength band including signal light and modulated light and cutting noise light having a wavelength outside the range of the wavelength band. Noise light can be generated, for example, in an optical transmission line or a light source. The optical filters 3s and 3t can be easily formed by various configurations such as lattice type, AWG (Arrayed Waveguide Gratings) type, and grating (for example, Optics Express Vol. 24, Issue 26, pp. 29577-, which is a non-patent document. 29582 (2016)).

In the optical module 100 configured as described above, the optical integrated circuit 3 which is a SiPh circuit outputs laser light that has passed through a plurality of integrated waveguides and a plurality of optical elements to the InP system modulator 2. The modulator 2 generates the modulated light, the optical integrated circuit 3 receives the modulated light, and outputs the modulated light that has passed through the integrated plurality of waveguides and the plurality of optical elements. Therefore, the InP-based modulator 2 is suitable for high-speed modulation, and the space propagation location is reduced as much as possible by the optical integrated circuit 3 which is a SiPh circuit, and the internal waveguide propagation is utilized to enable assembly and aging. Optical misalignment can be suppressed, and optical loss such as coupling loss can be suppressed. In particular, since the modulator 2 composed of different material systems and the optical integrated circuit 3 are coupled at the minimum optical coupling points, the effect of suppressing optical loss is remarkable. Further, in the optical module 100, the number of parts and the cost of parts are reduced, and the cost can be reduced.

In the optical module 100, a portion including a tunable light source 1 and a modulator 2 constitutes an optical transmission unit, and a portion including a coherent mixer 3k constitutes an optical reception unit. Such an optical module 100 can be applied to Type-II of IC-TROSA (integrated coherent transmitter-receiver optical sub-assembly) by, for example, OIF (Optical Internetworking Forum).

(Embodiment 2)
FIG. 2 is a schematic diagram showing the configuration of the optical module according to the second embodiment. The optical module 100A has a configuration in which the optical integrated circuit 3 is replaced with the optical integrated circuit 3A and the beam splitter 7A and the optical coupling element 16A are added in the configuration of the optical module 100 shown in FIG. The optical integrated circuit 3A has a configuration in which the beam splitter 3b, the optical equalizer 3j, and the optical filters 3s and 3t are deleted in the configuration of the optical integrated circuit 3.

An example of the function of the optical module 100A will be described.
The optical coupling element 16A couples the laser beam from the tunable light source 1 to the beam splitter 7A by spatial coupling. The beam splitter 7A is an optical element that is not integrated and is spatially coupled to the optical coupling element 11. The beam splitter 7A passes most of the laser light and outputs it to the beam splitter 3c via the optical coupling element 11 and the waveguide of the optical integrated circuit 3A, and at the same time, a part of the beam splitter 7A is branched to the optical coupling element 11 and the optical coupling element 11. It is output to the optical branching element 3a via the waveguide of the optical integrated circuit 3A. The optical branching element 3a passes most of the guided laser light through the waveguide of the optical integrated circuit 3 and outputs it to the coherent mixer 3k via the waveguide, and at the same time, partially branches and outputs it to the monitor PD3n. do.

Since the other functions of the optical module 100A are the same as the functions of the optical module 100, the description thereof will be omitted.

Even in the optical module 100A configured as described above, optical loss can be suppressed, the number of parts and the cost of parts can be reduced, and cost reduction can be realized. Further, such an optical module 100A can be applied to, for example, a Type-II of IC-TROSA.

(Embodiment 3)
FIG. 3 is a schematic diagram showing the configuration of the optical module according to the third embodiment. The optical module 100B has a configuration in which the optical integrated circuit 3 is replaced with the optical integrated circuit 3B and the wavelength rocker 4 and the optical coupling element 13 are deleted in the configuration of the optical module 100 shown in FIG.

The optical integrated circuit 3B has a configuration in which the wavelength rocker 3u is added and the optical equalizer 3j is deleted in the configuration of the optical integrated circuit 3. The wavelength rocker 3u has the same configuration and function as the wavelength rocker 4, but is different in that it is configured to include a silicon-based semiconductor material and is integrated in the optical integrated circuit 3B.

An example of the function of the optical module 100B is the same as the function of the optical module 100, but the beam splitter 3c branches a part of the laser beam from the beam splitter 3b and outputs it to the wavelength rocker 3u via the waveguide. The point to do is different.

Even in the optical module 100B configured as described above, optical loss can be suppressed, the number of parts and the cost of parts can be reduced, and cost reduction can be realized. Further, such an optical module 100B can be applied to, for example, an IC-TROSA Type-II.

(Embodiment 4)
FIG. 4 is a schematic diagram showing the configuration of the optical module according to the fourth embodiment. In the configuration of the optical module 100 shown in FIG. 1, the optical module 100C replaces the optical integrated circuit 3 with the optical integrated circuit 3C, deletes the wavelength variable light source 1, the wavelength rocker 4, and the optical coupling elements 11 and 13, and optically couples them. It has a configuration in which an element 17C and an optical fiber 8C are added.

The optical integrated circuit 3C has a configuration in which the beam splitter 3Cb is added, the beam splitter 3b and 3c, the optical equalizer 3j, the monitor PD3n, and the optical filters 3s and 3t are deleted in the configuration of the optical integrated circuit 3.

An example of the function of the optical module 100C will be described.
The optical fiber 8C propagates the laser light from the outside and outputs it to the optical coupling element 15. The laser light has the same characteristics as the laser light output by the tunable light source 1. The optical coupling element 17C couples the laser beam from the optical fiber 8C to the waveguide of the optical integrated circuit 3C.

In the optical integrated circuit 3C, the beam splitter 3Cb passes most of the guided laser light through the waveguide of the optical integrated circuit 3C and outputs it to the optical coupling element 12, and at the same time, a part of the beam splitter 3C is branched into the coherent mixer 3k. Output.

That is, a part of the light input from the optical fiber 8C is modulated by the modulator 2 to become the modulated light, and a part of the light is used as local emission in the coherent mixer 3k.

Since the other functions of the optical module 100C are the same as the functions of the optical module 100, the description thereof will be omitted.

Even in the optical module 100C configured as described above, optical loss can be suppressed, the number of parts and the cost of parts can be reduced, and cost reduction can be realized. Further, such an optical module 100B can be applied to, for example, a Type-I of an IC-TROSA.

(Embodiment 5)
FIG. 5 is a schematic diagram showing the configuration of the optical module according to the fifth embodiment. The optical module 100D has a configuration in which the optical integrated circuit 3C is replaced with the optical integrated circuit 3D and the optical coupling element 15 and the optical fiber 6 are deleted in the configuration of the optical module 100C shown in FIG.

The optical integrated circuit 3D has a configuration in which the beam splitter 3Cb, the coherent mixer 3k, the optical branching element 3l, the high-speed PD3m, and the monitor PD3r are deleted in the configuration of the optical integrated circuit 3C.

An example of the function of the optical module 100D will be described.
The optical fiber 8C propagates the laser light from the outside and outputs it to the optical coupling element 15. The laser light has the same characteristics as the laser light output by the tunable light source 1. The optical coupling element 17C couples the laser beam from the optical fiber 8C to the waveguide of the optical integrated circuit 3C.

In the optical integrated circuit 3C, the waveguide outputs the guided laser beam to the optical coupling element 12.

That is, the light input from the optical fiber 8C is modulated by the modulator 2 to become modulated light. Further, the optical module 100D has no function related to the coherent mixer.

Since the other functions of the optical module 100D are the same as the functions of the optical module 100C, the description thereof will be omitted.

Even in the optical module 100D configured as described above, optical loss can be suppressed, the number of parts and the cost of parts can be reduced, and cost reduction can be realized. Further, such an optical module 100B can be applied to, for example, an HB-CDM (High Bandwidth Coherent Driver Modulator) by OIF.

(Embodiment 6)
FIG. 6 is a schematic diagram showing the configuration of the optical module according to the sixth embodiment. FIG. 7 is a side view of a part of the optical module shown in FIG. The optical module 100E has a configuration in which a temperature control element 21 and a spacer 22 are added in the configuration of the optical module 100 shown in FIG.

The temperature control element 21 includes a tunable light source 1, a wavelength rocker 4, and a modulator 2. Further, the temperature control element 21 is equipped with a part of the optical integrated circuit 3. Specifically, the temperature control element 21 mounts a portion of the optical integrated circuit 3 around a portion that is optically coupled to the wavelength tunable light source 1, the modulator 2, and the wavelength rocker 4. Here, mounting is an example of an embodiment that realizes thermal contact.

The spacer 22 is equipped with an optical integrated circuit 3. The height of the spacer 22 is adjusted so that a part of the optical integrated circuit 3 can be mounted on the temperature control element 21.

Since the function of the optical module 100E is the same as the function of the optical module 100C, the description thereof will be omitted.

Even in the optical module 100E configured as described above, optical loss can be suppressed, the number of parts and the cost of parts can be reduced, and cost reduction can be realized. Further, in the optical module 100E, since the temperature control element 21 is in thermal contact with the modulator 2, the temperature of the modulator 2 can be maintained at a substantially constant temperature, and the modulation characteristics of the modulator 2 can be improved. Can be stable. Further, since the temperature control element 21 is in thermal contact with the periphery of the portion of the optical integrated circuit 3 that is optically coupled to the modulator 2, the portion of the optical integrated circuit 3 that is optically coupled is in contact with the modulator 2. It is kept at about the same temperature. As a result, the occurrence of a situation in which the position shift occurs due to the difference in the coefficient of thermal expansion between the temperature control element 21 and the optical integrated circuit 3 and the optical loss increases is suppressed. Similarly, since the temperature control element 21 is thermally in contact with the tunable light source 1 and the wavelength rocker 4, the characteristics of the tunable light source 1 and the wavelength rocker 4 can be stabilized and the light loss can be achieved. The occurrence of the situation that the number increases is suppressed.

The portion of the optical integrated circuit 3 that is in thermal contact with the temperature control element 21 is the optical coupling element 11 and the modulator 2 that are optically coupled to the wavelength variable light source 1 in the waveguide of the optical integrated circuit 3. Includes the end face of each waveguide that is optically coupled to each of the optically coupled optical coupling element 12 and the optically coupled optical coupling element 13 to the wavelength rocker 4. Further, the size of the portion of the optical integrated circuit 3 that is in thermal contact with the temperature control element 21 is appropriately set depending on the allowable positional deviation or the like, and is, for example, the optical coupling elements 11, 12, and 13. It is a region of about 0.5 mm from the end face of optical coupling. Further, if all of the optical integrated circuits 3 are in thermal contact with the temperature control element 21, the power consumption of the temperature control element 21 becomes excessively large, so that the optical integrated circuit 3 mounted on the temperature control element 21 It is preferably 50% or less of the surface area.

(Silicon platform)
The optical integrated circuit described in each of the above embodiments may be integrally configured with a base including a silicon-based semiconductor material. FIG. 8 is a schematic diagram showing, as an example, the configuration of a silicon platform 30 including a portion in which an optical integrated circuit 3 and a base 31 are integrally configured. The silicon platform 30 has a configuration in which an optical integrated circuit 3 is provided on a part of the main surface of a flat plate-shaped base 31. Further, the silicon platform 30 includes countersunk portions 31a and 31b and optical fiber mounting portions 31c and 31d on a part of the main surface. The optical fiber mounting portions 31c and 31d project from the main surface of the base 31, and grooves 31ca and 31da are provided on the upper surface thereof, respectively. In the present embodiment, the grooves 31ca and 31da are V grooves, but may be U grooves.

FIG. 9 is a schematic diagram showing a mounting state of the silicon platform 30. In FIG. 9, as an example, the modulator 2 is mounted on the countersunk portion 31a, and the tunable light source 1 is mounted on the countersunk portion 31b. The counterbore portion 31a is an example of a modulator mounting unit, and the counterbore portion 31b is an example of a tunable light source mounting unit. Further, the optical fiber 5 is mounted on the optical fiber mounting portion 31c so that a part of the optical fiber is accommodated in the groove 31ca. The optical fiber 6 is mounted on the optical fiber mounting portion 31d so that a part of the optical fiber is accommodated in the groove 31da.

The optical integrated circuit 3, the counterbore portions 31a and 31b, and the optical fiber mounting portions 31c and 31d are formed by a silicon process so that their relative positions are highly accurate. In an optical module using such a silicon platform 30, the accuracy of the relative positions of the modulator 2, the optical integrated circuit 3, and the optical fibers 5 and 6 is high, and the optical loss is further suppressed.

In the above embodiment, the wavelength variable light source 1, the modulator 2, and the wavelength rocker 4 are optically coupled to the optical integrated circuit by an optical coupling element, but are optically coupled by a butt joint junction. It is also good. In this case, the number of optical coupling elements used can be further reduced. For example, in the modulator 2 and the optical integrated circuit, the waveguides that input and output light to each other are optically coupled by a butt joint junction.

Further, in the above embodiment, the modulator 2 may include an optical amplifier that amplifies the light input to the modulation signal addition units 2b and 2c or the modulated light. The optical amplifier is, for example, a semiconductor optical amplifier configured to include an InP-based semiconductor material. Such a semiconductor optical amplifier can also be integrated together with the modulation signal addition units 2b and 2c.

Further, in the above embodiment, a silicon lens may be integrated as an optical element in the optical integrated circuit. Further, in the optical integrated circuit or platform, a transimpedance amplifier (TIA) that converts a current signal output from a high-speed PD3m into a voltage signal, a DRV (Digital Modulator Driver) that drives a modulator 2, and a controller are used. Control ICs and the like may be integrated. Further, an optical isolator, a DC blocking, or a terminator may be integrated in the optical integrated circuit. Further, the optical equalizer may be provided outside the optical integrated circuit.

Further, in the above embodiment, the optical integrated circuit is configured by a single chip, but the coherent mixer and other parts are configured by separate chips, and these are optically bonded by a butt joint or an optical coupling element. It is also good.

Further, the present invention is not limited to the above embodiments. The present invention also includes a configuration in which the above-mentioned components are appropriately combined. Further, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspect of the present invention is not limited to the above embodiment, and various modifications can be made.

1: Variable wavelength light source 2: Modulator 2a: Optical branch 2b, 2c: Modulation signal addition unit 3, 3A, 3B, 3C: Optical integrated circuit 3b, 3c, 3Cb, 7A: Beam splitter 3D: Optical integrated circuit 3a: Optical branching element 3d, 3e: Variable optical attenuation element 3f, 3g, 3i: Optical branching element 3h: Polarization synthesis element 3j: Optical equalizer 3k: Coherent mixer 3l: Optical branching element 3m: High-speed PD
3n, 3o, 3p, 3q, 3r: Monitor PD
3s, 3t: Optical filter 3u, 4: Wavelength rocker 5, 6, 8C: Optical fiber 11, 12, 13, 14, 15, 16A, 17C: Optical coupling element 21: Temperature control element 22: Spacer 30: Silicon platform 31 : Base 31a, 31b: Counterbore 31c, 31d: Optical fiber mounting part 31ca, 31da: Groove 100, 100A, 100B, 100C, 100D, 100E: Optical module

Claims (17)

A modulator containing an InP-based semiconductor material and having a modulation signal addition unit that modulates the input light, and
An optical integrated circuit that is optically coupled to the modulator and has a plurality of waveguides including a silicon-based semiconductor material and a plurality of optical elements integrated.
Equipped with
The optical integrated circuit outputs light that has passed through either of the waveguides or any of the optical elements to the modulator, receives the modulated light generated by the modulator modulating the light, and guides the light. An optical module that outputs the modulated light that has passed through any other waveguide or other optical element. The optical module according to claim 1, wherein the optical coupling is made by a butt joint or an optical coupling element. The optical module according to claim 2, wherein the optical coupling element includes a lens, a GRIN lens, an optical fiber, a waveguide, or a photonic wire. The optical module according to any one of claims 1 to 3, wherein the modulator includes light input to the modulation signal addition unit or an optical amplifier for amplifying the modulation light. The optical module according to any one of claims 1 to 4, wherein the optical integrated circuit includes a lens, a light receiving element, a polarization synthesis element, or a variable light attenuation element as the optical element. The optical integrated circuit according to any one of claims 1 to 4, wherein the optical integrated circuit includes a light receiving element and an optical branching element that branches a part of the passing light and outputs the light to the light receiving element. Optical module. The modulator includes two modulation signal addition units as the modulation signal addition unit.
The optical integrated circuit includes a polarization synthesis element and two variable light attenuation elements as the optical element.
The two variable light attenuation elements attenuate the two modulated lights generated by the two modulated signal addition units, respectively.
The optical module according to any one of claims 1 to 4, wherein the polarization synthesizing element is a polarization synthesizing of the two attenuated modulated lights. The optical module according to any one of claims 1 to 7, wherein the optical integrated circuit includes an optical filter and an optical equalizer. The optical module according to any one of claims 1 to 8, further comprising an optical fiber that optically couples with the optical integrated circuit. The optical module according to any one of claims 1 to 8, wherein the optical integrated circuit includes a silicon-based semiconductor material and is integrally configured with a base including a modulator mounting unit for mounting the modulator. The optical module according to claim 10, wherein the base includes an optical fiber mounting unit for mounting an optical fiber. The optical module according to any one of claims 1 to 11, further comprising a light source that outputs light that is input to the optical integrated circuit and output to the modulator. The optical module according to claim 12, further comprising a wavelength detector for detecting the wavelength of the light output from the light source. The optical module according to claim 13, wherein the wavelength detector is integrated in the optical integrated circuit. The optical module according to any one of claims 1 to 14, wherein the optical integrated circuit includes a coherent mixer as the optical element. The optical module according to claim 15, wherein the optical integrated circuit includes, as the optical element, a light receiving element that receives light output from the coherent mixer. The invention according to any one of claims 1 to 16, further comprising a temperature control element that is in thermal contact with the modulator and the periphery of the portion of the optical integrated circuit that is optically coupled to the modulator. Optical module.

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