Optical device, wafer and optical transceiver

Abstract

The invention relates to an optical device, a wafer and an optical transceiver. The optical device is an optical device formed on a wafer. The optical device includes: an optical circuit; a grating coupler; and an optical switch including a first port connected to the grating coupler, a second port connected to the optical circuit, and a third port connected to the loop mirror through a phase shifter.

Description

Technical Field

[0001] The embodiments discussed herein relate to optical devices, wafers, and optical transceivers. Background Art

[0002] Fig. 9 is an explanatory diagram illustrating one example of a conventionally used test system 200 . Fig. 9 The test system 200 shown includes a test device 210, an optical chip 220, and an optical fiber 230. The test device 210 includes a light source 211, a polarization controller 212, a circulator 213, and a power meter 214.

[0003] The light source 211 is a light source that emits, for example, a test light corresponding to received light, local emission light, or transmitted light. The polarization controller 212 polarizes the test light received from the light source 211, and outputs the polarized test light to the circulator 213. In addition, the polarization controller 212 performs polarization control on the test light, and generates a test light having TM polarization or TE polarization. The circulator 213 outputs the test light incident from the polarization controller 212 to the optical fiber 230, and outputs the reflected return light relative to the test light incident from the optical fiber 230 to the power meter 214. The power meter 214 receives the reflected return light relative to the test light that has been received from the optical circuit 222 from the circulator 213, and measures the power of the reflected return light.

[0004] The optical chip 220 is, for example, an optical IC chip such as a digital coherent optical transmitter / receiver. The optical chip 220 is an optical chip cut from a wafer. The optical chip 220 includes an optical port 221, an optical circuit 222, and an optical waveguide 223. Since the wafer is chip-formed, the optical port 221 appears on an end 224 of the side surface of the optical chip 220 accordingly. The optical waveguide 223 is a waveguide for guiding light between the optical port 221 and the optical circuit 222. The optical circuit 222 is a circuit such as an optical transmitter, an optical receiver, etc., which is provided in the digital coherent optical transmitter / receiver.

[0005] In a conventional test method for testing the optical chip 220, the optical chip 220 is cut out from a wafer, and each cut optical chip 220 is placed on a stage. In addition, a portion between an output side of a circulator 213 included in the test device 210 and an optical port 221 provided at an end 224 of a side surface of the optical chip 220 is connected by an optical fiber 230. Then, the test device 210 measures the power of the reflected return light with respect to the test light by using a power meter 214, and evaluates the optical chip 220 based on the measurement result.

[0006] However, in a conventional test method for testing the optical chip 220, alignment work for aligning the optical port 221 and the optical axis of the optical fiber 230 is required for each optical chip 220. Therefore, the workload increases when measuring the power of the reflected return light with respect to the test light by optically connecting the optical chip 220 and the test device 210.

[0007] In addition, it is conceivable that if the optical chip 220 can be tested in a wafer state before being chip-formed, the work efficiency can be improved, but if the test is performed in a wafer state, it is necessary to input light from the direction of the wafer surface using an optical fiber. Therefore, a test system 100 using this test method will be described.

[0008] Figure 8 1 is an explanatory diagram illustrating an example of a conventionally used test system 100. The test system 100 includes a wafer made of, for example, silicon, on which a plurality of optical chips 110 are formed, a test device 210, and an optical fiber 230. Fig. 9 For components in the illustrated testing apparatus 210 that have the same configuration, repeated descriptions of their configurations and operations will be omitted.

[0009] On the wafer, a plurality of optical chips 110 are formed in a grid arrangement state. The optical chip 110 includes an optical circuit chip 110A, a test circuit chip 110B, and a cutting line 110C capable of cutting between the optical circuit chip 110A and the test circuit chip 110B. The optical circuit chip 110A includes an optical port 111A, an optical circuit 112A, and a first optical waveguide 113A that optically couples the optical port 111A with the optical circuit 112A. As the wafer is chip-ized, the optical port 111A appears on the end of the side surface of the optical chip 110 accordingly. The optical circuit 112A is a circuit such as an optical transmitter, an optical receiver, etc., which is provided in a digital coherent optical transmitter / receiver. The first optical waveguide 113A is a waveguide used to guide light between the optical port 111A and the optical circuit 112A.

[0010] The test circuit chip 110B includes a grating coupler (GC) 111B and a second optical waveguide 112B. The GC 111B is arranged on the surface of the test circuit chip 110B, detachably connected to the optical fiber 230, and connected to the second optical waveguide 112B. The second optical waveguide 112B is optically connected to the optical port 111A included in the optical circuit chip 110A.

[0011] The testing device 210 includes a light source 211 , a polarization controller 212 , a circulator 213 , and a power meter 214 .

[0012] The operation of the test system 100 will be described below. The polarization controller 212 included in the test device 210 polarizes the test light received from the light source 211, and outputs the polarized test light to the circulator 213. The circulator 213 outputs the polarized test light to the optical fiber 230. The GC 111B provided on the test circuit chip 110B inputs the test light received from the optical fiber 230 to the second optical waveguide 112B. In addition, the optical circuit chip 110A receives the test light from the optical port 111A connected to the second optical waveguide 112B, and inputs the incident test light to the first optical waveguide 113A.

[0013] The first optical waveguide 113A inputs the test light to the optical circuit 112A. The optical circuit 112A outputs the reflected return light with respect to the test light to the first optical waveguide 113A. The first optical waveguide 113A outputs the reflected return light to the second optical waveguide 112B through the optical port 111A. The second optical waveguide 112B outputs the reflected return light received from the first optical waveguide 113A to the optical fiber 230 through the GC 111B. In addition, the circulator 213 outputs the reflected return light received from the optical fiber 230 to the power meter 214.

[0014] The power meter 214 measures the power of the reflected return light relative to the test light received from the circulator 213. In the test system 100, light can be incident by approaching the optical fiber 230 to the GC 111B from the wafer surface direction, and the test light can be input to the optical circuit 112A, so that the test can be performed in the wafer state. The test device 210 evaluates the optical circuit chip 110A based on the measurement result of the reflected return light received from the optical circuit 112A.

[0015] Patent Document 1: U.S. Patent Application Publication No. 2022 / 0065743

[0016] Patent Document 2: Japanese Laid-Open Patent Publication No. 2020-181076

[0017] Patent Document 3: Japanese Laid-Open Patent Publication No. 2020-72345

[0018] In the test device 210 included in the conventionally used test system 100, the reflected return light received from the optical circuit 112A is measured. However, in the test device 210, the reflected light with respect to the test light is generated with respect to the GC 111B connected to the optical fiber 230, so that the reflected light with respect to the test light received from the GC 111B is correspondingly included in the measured value of the reflected return light. Therefore, it is difficult to obtain the reflected return light received from the optical circuit 112A with high accuracy.

[0019] Therefore, an object of one aspect of an embodiment of the present invention is to provide an optical circuit or the like capable of obtaining reflected return light with respect to light from the optical circuit with high accuracy. Summary of the invention

[0020] According to one aspect of the embodiment, an optical device is formed on a wafer. The optical device includes an optical circuit, a grating coupler, and an optical switch. The optical switch includes a first port connected to the grating coupler, a second port connected to the optical circuit, and a third port connected to a loop mirror through a phase shifter. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is an explanatory diagram illustrating one example of a test system according to the first embodiment;

[0022] Figure 2 is a plan view illustrating one example of a wafer on which an optical chip is formed;

[0023] Figure 3 is an explanatory diagram illustrating one example of a test system according to a second embodiment;

[0024] Figure 4 is an explanatory diagram illustrating one example of a test system according to a third embodiment;

[0025] Figure 5 is an explanatory diagram illustrating an example of a test system according to a fourth embodiment;

[0026] Figure 6 is an explanatory diagram illustrating an example of a test system according to a fifth embodiment;

[0027] Figure 7 is an explanatory diagram illustrating one example of an optical transceiver including an optical chip;

[0028] Figure 8 is an explanatory diagram illustrating one example of a conventionally used test system; and

[0029] Fig. 9 is an explanatory diagram illustrating an example of a conventionally used test system. DETAILED DESCRIPTION

[0030] The preferred embodiments of the present invention will be explained with reference to the accompanying drawings. In addition, the disclosed technology is not limited to the embodiments. In addition, each embodiment can be used in any appropriate combination as long as it does not conflict with each other.

[0031] (a) First Embodiment

[0032] Figure 1is an explanatory diagram illustrating one example of the test system according to the first embodiment. Figure 1 The test system 1 shown includes an optical chip 3, a test device 2, and an optical fiber 4 optically connecting the optical chip 3 to the test device 2. The optical chip 3 is, for example, an optical IC chip including an optical circuit such as a digital coherent optical transmitter / receiver. The test device 2 is an evaluation device for evaluating the optical chip 3.

[0033] Figure 2 is a plan view illustrating an example of a wafer 5 on which an optical chip 3 is formed. For example, Figure 2 The wafer 5 shown is a silicon wafer. On the wafer 5, a plurality of optical chips 3 are formed in a grid arrangement state. The optical chip 3 is an optical device including an optical circuit chip 3A, a test circuit chip 3B, and a cutting line 3C capable of cutting between the optical circuit chip 3A and the test circuit chip 3B.

[0034] The optical circuit chip 3A includes an optical port 22, an optical circuit 21, and a first optical waveguide 23 optically connecting the optical port 22 and the optical circuit 21. The optical port 22 is present on the end of the side surface of the optical circuit chip 3A due to chip-forming of the wafer 5. The optical circuit 21 is a circuit such as an optical transmitter, an optical receiver, etc. provided in a digital coherent optical transmitter / receiver. The first optical waveguide 23 is a waveguide for guiding light between the optical port 22 and the optical circuit 21.

[0035] The test circuit chip 3B includes a grating coupler (GC) 31, an optical switch 32, a second optical waveguide 33, a phase shifter (PS) 34, and a loop mirror 35. The GC 31 is arranged on the surface of the test circuit chip 3B, is detachably connected to the optical fiber 4 connected to the test device 2, and is connected to the optical switch 32. The optical switch 32 is configured by a 1×2 optical switch having a single input port and two output ports. The optical switch 32 includes a first port 32A connected to the GC 31, a second port 32B connected to the second optical waveguide 33, and a third port 32C connected to the PS 34. The optical switch 32 branches the test light received from the GC 31, and outputs the branched test light to the second port connected to the second optical waveguide 33 and the third port connected to the PS 34. The second optical waveguide 33 is an optical waveguide optically connected to the optical port 22 of the optical circuit chip 3A. Furthermore, in the optical switch 32 , the branching ratio between the second port 32B and the third port 32C is set so that the test light of the same level as the reflected light with respect to the test light received from the GC 31 can be obtained from the third port 32C.

[0036] In order to cancel the reflected light with respect to the test light received from the GC 31, the PS 34 functions to generate the return light of the test light received from the third port 32C as the cancel light with the opposite phase. The PS 34 changes the phase of the test light received from the third port 32C included in the optical switch 32 by 180 degrees in the direction in which the reflected light with respect to the test light received from the GC 31 is canceled. The PS 34 transmits the test light that has been input from the third port 32C and then outputs the test light to the loop mirror 35. Then, the loop mirror 35 returns the test light that has been input from the PS 34 to the PS 34 by taking another path. Then, the PS 34 changes the phase of the test light that has been input from the loop mirror 35 to the opposite phase of the reflected light, and outputs the test light whose phase has been changed as the return light to the third port 32C included in the optical switch 32.

[0037] The test device 2 includes a light source 11, a polarization controller 12, a circulator 13, and a power meter 14. The light source 11 is an LD that emits a test light. The polarization controller 12 polarizes the test light received from the light source 11, and outputs the polarized test light to the circulator 13. The circulator 13 outputs the polarized test light received from the polarization controller 12 to the optical fiber 4. The circulator 13 obtains the reflected return light that has been input from the second port 32B and has been received from the optical circuit 21, and then outputs the reflected return light to the power meter 14. The reflected return light relative to the test light is the reflected return light received from the optical circuit 21 relative to the test light. The power meter 14 measures the power of the reflected return light received from the circulator 13. The test device 2 evaluates the optical circuit chip 3A based on the measurement result of the reflected return light measured by the power meter 14.

[0038] The optical switch 32 outputs the return light that has been input from the third port 32C and the reflected return light with respect to the test light that has been input from the second port 32B and has been received from the optical circuit 21 to the circulator 13 included in the test device 2 through the GC 31 and the optical fiber 4. The circulator 13 can obtain the reflected return light that has been input from the second port 32B and has been received from the optical circuit 21 with high accuracy by mutually canceling the reflected light of the test light received from the GC 31 and the return light that has been input from the third port 32C. Then, the circulator 13 outputs the reflected return light to the power meter 14 included in the test device 2.

[0039] Hereinafter, the operation of the test system 1 according to the present embodiment will be described. First, the wafer 5 is placed on the wafer probe. Then, since the test circuit chip 3B included in the optical chip 3 on the wafer 5 is moved, when the GC 31 included in the test circuit chip 3B is optically connected to the optical fiber 4, the test operation is started.

[0040] The polarization controller 12 polarizes the test light received from the light source 11, and inputs the polarization test light to the circulator 13. The circulator 13 outputs the polarization test light to the optical fiber 4. The GC 31 connected to the optical fiber 4 outputs the received polarization test light to the optical switch 32. The optical switch 32 inputs the polarization test light received from the first port 32A, and branches and outputs the polarization test light to the second port 32B and the third port 32C.

[0041] The optical switch 32 outputs the polarization test light from the second port 32B to the second optical waveguide 33, and outputs the polarization test light to the optical port 22 of the optical circuit chip 3A. The optical circuit chip 3A inputs the polarization test light received from the optical port 22 to the first optical waveguide 23. The optical circuit 21 included in the optical circuit chip 3A inputs the polarization test light received from the first optical waveguide 23, and outputs the reflected return light with respect to the polarization test light to the first optical waveguide 23. The second optical waveguide 33 included in the test circuit chip 3B inputs the reflected return light received from the optical port 22 to the second port 32B included in the optical switch 32.

[0042] In addition, when the optical switch 32 branches and outputs the polarized test light that has been input from the first port 32A to the second port 32B and the third port 32C, the optical switch 32 outputs the polarized test light from the third port 32C to the PS 34. The PS 34 outputs the test light that has been input from the third port 32C to the loop mirror 35. The loop mirror 35 returns the test light that has been input from the PS 34 to the PS 34 as return light. Then, the PS 34 performs phase adjustment on the return light that has been input from the loop mirror 35, and inputs the return light that has been phase-adjusted to the third port 32C of the optical switch 32. In addition, the return light that has been phase-adjusted is light that cancels out the reflected light with respect to the test light received from the GC 31.

[0043] The optical switch 32 multiplexes both the reflected return light that has been input from the second port 32B and the return light that has been input from the third port 32C and has been phase-adjusted, and then outputs the reflected return light including the multiplexed return light to the GC 31. In addition, in the GC 31, reflected light with respect to the test light received from the circulator 13 is generated.

[0044] Then, since the return reflected light including the return light received from the first port 32A of the optical switch 32 and the reflected light generated from the GC 31 is input to the circulator 13, the circulator 13 outputs only the return reflected light to the power meter 14 by canceling the reflected light by the return light. The power meter 14 measures the power of the reflected return light. In addition, the test device 2 can evaluate the optical circuit chip 3A based on the measurement result of the power meter 14.

[0045] Then, in Figure 2 In the case where the measurement and evaluation operation of the power of the reflected return light of the optical circuit chip 3A included in all the optical chips 3 arranged in each row on the wafer 5 shown is completed, the test device 2 cuts the wafer 5 along the cutting line 3C of all the optical chips 3 arranged in each row. Then, the test device 2 starts the measurement operation of measuring the reflected return light of each optical chip 3 arranged in the subsequent row, and continues the cutting process until the measurement operation performed on all the optical chips 3 arranged on the wafer 5 is completed. In addition, by cutting the wafer 5 along the cutting line 3C set on each optical chip 3, the optical circuit chip 3A and the test circuit chip 3B included in the optical chip 3 can be divided into parts, so that the optical circuit chip 3A can be obtained.

[0046] The optical chip 3 includes: an optical circuit 21; a GC 31; and an optical switch 32, which includes a first port 32A connected to the GC 31, a second port 32B connected to the optical circuit 21, and a third port 32C connected to the loop mirror 35 through the PS 34. In the optical switch 32, the branching ratio between the second port 32B and the third port 32C is set so that the return light of the same level as the reflected light received from the GC 31 with respect to the test light can be obtained from the third port 32C. In the PS 34, the phase shift amount of the return light transmitted to the third port 32C is set in a direction in which the reflected light received from the GC 31 is canceled out. In other words, the branching ratio between the phase shift amounts of the optical switch 32 and the PS 34 is adjusted in advance so that the reflected light received from the GC 31 and the return light received from the PS 34 cancel each other, so that the test device 2 can measure the reflected return light received from the optical circuit 21 with high accuracy while suppressing the reflected light generated in the GC 31. Therefore, by suppressing the reflected light received from the GC 31 , the optical circuit chip 3A can be accurately evaluated based on the measurement result of the reflected return light received from the optical circuit 21 .

[0047] By optically connecting the optical chip 3 to the test device 2, the working efficiency when measuring the power of the reflected return light with respect to the test light can be improved.

[0048] In addition, for the convenience of description, a case is described herein as an example in which the PS 34 performs phase adjustment on the return light received from the loop mirror 35, and inputs the return light having undergone the phase adjustment to the third port 32C of the optical switch 32. However, the example is not limited thereto, and after the PS 34 performs phase adjustment on the test light having been input from the third port 32C, the PS 34 may output the test light having undergone the phase adjustment to the loop mirror 35, and may output the test light returned from the loop mirror 35 as the return light to the PS 34. Then, the PS 34 may transmit the return light having been input from the loop mirror 35 and input the return light to the third port 32C, and may be modified appropriately.

[0049] (b) Second Embodiment

[0050] Figure 3 1 is an explanatory diagram illustrating an example of a test system 1A according to a second embodiment. In addition, by assigning the same reference numerals to components having the same configuration as those in the test system 1 according to the first embodiment, repeated description of the configuration and its operation will be omitted. The test system 1A according to the second embodiment is different from the test system 1 according to the first embodiment in that the test system 1A includes a test circuit chip 3B1 in which a variable optical attenuator (VOA) 36 is arranged on a second optical waveguide 33 provided between the first optical waveguide 23 and the optical switch 32.

[0051] After the VOA 36 has transmitted the test light transmitted from the second port 32B to the optical circuit 21, the VOA 36 blocks the test light transmitted from the second port 32B to the optical circuit 21. Then, the PS 34 adjusts and sets in advance the phase shift amount of the test light transmitted to the third port 32C in the direction in which the reflected light input to the GC 31 is canceled while the VOA 36 blocks the test light. In addition, the optical switch 32 also adjusts and sets in advance the optical branching ratio between the second port 32B and the third port 32C in the direction in which the reflected light input to the GC 31 is canceled while the VOA 36 blocks the test light.

[0052] In the optical switch 32, the branching ratio between the second port 32B and the third port 32C is set so that the return light of the same level as the reflected light received from the GC 31 can be obtained while the test light transmitted from the second port 32B to the optical circuit 21 is blocked by the VOA 36. In the PS 34, the phase shift amount of the return light transmitted to the third port 32C is set in the direction of canceling the reflected light received from the GC 31 while blocking the test light transmitted from the second port 32B to the optical circuit 21. Therefore, the phase shift amount to be set in the PS 34 and the branching ratio to be set in the optical switch 32 can be set with high accuracy to cancel the reflected light received from the GC 31.

[0053] In addition, a case is described as an example in which the optical switch 32 included in the test circuit chip 3B in the test system 1 according to the first embodiment is configured by a 1×2 switch. However, components other than the reflected return light that has been input from the second port 32B and the return light that has been input from the third port 32C correspond to radiated light. Therefore, this radiated light returns to the optical circuit 21 or the GC 31 and becomes noise, so that the measurement accuracy of the reflected return light is reduced. Therefore, an embodiment that solves this situation will be described below as a third embodiment.

[0054] (c) Third Embodiment

[0055] Figure 4 1B is an explanatory diagram illustrating an example of a test system 1B according to the third embodiment. In addition, by assigning the same reference numerals to components having the same configuration as those in the test system 1 according to the first embodiment, repeated descriptions of their configurations and operations will be omitted. The test system 1 according to the first embodiment is different from the test system 1B according to the third embodiment in that the test system 1B includes a test circuit chip 3B2 in which an optical switch 37 having a 2×2 configuration is used instead of the optical switch 32 having a 1×2 configuration.

[0056] The optical switch 37 is configured by a 2×2 optical switch having two input ports and two output ports. The input ports provided in the optical switch 37 include a first port 37A connected to the GC 31 and a fourth port 37D. The output ports provided in the optical switch 37 include a second port 37B connected to the second optical waveguide 33 and a third port 37C connected to the PS 34. The optical switch 37 branches and outputs the test light received from the GC 31 to the second port 37B and the third port 37C based on a branching ratio set in advance. The branching ratio between the second port 37B and the third port 37C is set so that the test light of the same level as the reflected light with respect to the test light received from the GC 31 can be obtained from the third port 37C. In addition, the branching ratio between the first port 37A and the fourth port 37D included in the optical switch 37 is the same as the branching ratio between the second port 37B and the third port 37C. In addition, the optical switch 37 is a 2×2 optical switch, so that the optical switch 37 can control the radiated light generated in the 1×2 optical switch 32.

[0057] The test circuit chip 3B2 uses the 2×2 optical switch 37 , so that the generation of radiated light can be suppressed. Therefore, in the test device 2 , the measurement accuracy of the reflected return light received from the optical circuit 21 is improved.

[0058] (d) Fourth Embodiment

[0059] Figure 5 1B1 according to the fourth embodiment. In addition, by assigning the same reference numerals to components having the same configuration as those in the test system 1B according to the third embodiment, repeated descriptions of the configuration and operation thereof will be omitted. The test system 1B according to the third embodiment is different from the test system 1B1 according to the fourth embodiment in that an optical terminal 38 is optically connected to a fourth port 37D included in an optical switch 37 having a 2×2 configuration. The optical terminal 38 used may be, for example, an optical absorption member that absorbs light. The optical absorption member may be made of, for example, a metal, a semiconductor film, or a metal doped with Si.

[0060] The optical switch 37 is configured so that the optical terminal 38 is optically connected to the fourth port 37D, and light leaking from the fourth port 37D is absorbed by the optical terminal 38. Therefore, in the test device 2, the measurement accuracy of the reflected return light received from the optical circuit 21 is improved.

[0061] (e) Fifth Embodiment

[0062] Figure 61B is an explanatory diagram illustrating an example of a test system 1B2 according to the fifth embodiment. In addition, by assigning the same reference numerals to components having the same configuration as those in the test system 1B1 according to the fourth embodiment, repeated descriptions of their configurations and operations will be omitted. The test system 1B1 according to the fourth embodiment is different from the test system 1B2 according to the fifth embodiment in that a photodetector (PD) 39 is used instead of the optical terminal 38. The PD 39 is, for example, a photoelectric element that absorbs light. In addition, the PD 39 monitors part of the reflected return light by connecting an electrical signal that has been photoelectrically converted by a monitor, and finds a correlation with the value of the power meter 14, so that high-precision measurement of the reflected return light can be achieved with high precision.

[0063] The fourth port 37D is optically connected to the PD 39 so that light leaking from the fourth port 37D is absorbed by the PD 39. Therefore, in the test apparatus 2, the measurement accuracy of the reflected return light received from the optical circuit 21 is improved.

[0064] Figure 7 is an explanatory diagram illustrating one example of an optical transceiver 50 including the optical chip 3 . Figure 7 The optical transceiver 50 shown includes a laser diode (LD) 51, a digital signal processor (DSP) 52, and an optical transmission / reception device 53. The LD 51 is a light source that emits light. The optical transmission / reception device 53 is, for example, a digital coherent optical transmitter / receiver. The optical transceiver 50 includes an optical transmitter 53A that transmits signal light and an optical receiver 53B that receives signal light. The optical receiver 53B is, for example, an optical circuit chip 3A such as a digital coherent receiver that converts signal light into an electrical signal and is obtained after the test circuit chip 3B is cut off. The DSP 52 performs digital conversion on each electrical signal input from the optical receiver 53B. The optical transmitter 53A is, for example, an optical circuit chip 3A such as a digital coherent transmitter that modulates light according to the electrical signal received from the DSP 52 and is obtained after the test circuit chip 3B is cut off.

[0065] In addition, for the convenience of description, a case is described as an example in which the optical fiber 4 is fixed to the wafer prober and the wafer 5 mounted on the wafer prober moves up, down, left, and right relative to the optical fiber 4. However, the optical fiber 4 may be moved up, down, left, and right on the wafer 5, and appropriate modifications may be made.

[0066] Furthermore, a digital coherent transmitter / receiver is used as an example of the optical circuit chip 3A, but the example is not limited to the digital coherent technology, and an optical receiver or optical transmitter configured using another technology may be used, and appropriate modifications may be made.

[0067] Each component in the unit shown in the figure is not always physically configured as shown in the figure. In other words, the specific shape of the individual or integrated unit is not limited to the drawings; however, all or part of the units can be configured by functionally or physically separating or integrating any unit according to various loads or use conditions.

[0068] In addition, all or any part of the various processing functions performed by each unit may also be performed by a central processing unit (CPU) (or a microcomputer such as a microprocessing unit (MPU) or a microcontroller unit (MCU)). In addition, all or any part of the various processing functions may also be performed by a program analyzed and executed by a CPU (or a microcomputer such as an MPU or an MCU), or by hardware through wired logic.

[0069] According to an aspect of the embodiment, reflected return light with respect to light can be obtained from an optical circuit with high accuracy.

Claims

1. An optical device formed on a wafer, the optical device comprising: Optical circuits; Grating coupler; as well as An optical switch, comprising: a first port connected to the grating coupler; a second port connected to the optical circuit; and A third port is connected to the loop mirror through a phase shifter.

2. The optical device according to claim 1, wherein: the optical switch inputs input light from the first port, and in the optical switch, when the optical switch branches and outputs the input light having been input from the first port to the second port and the third port, a branching ratio between the second port and the third port is set so that return light having the same level as reflected light received from the grating coupler with respect to the input light can be obtained from the third port, and In the phase shifter, a phase shift amount of the return light transmitted to the third port is set in a direction in which the reflected light received from the grating coupler is canceled out.

3. The optical device according to claim 2, wherein: The optical device comprises: an optical circuit chip, the optical circuit chip comprising the optical circuit; and a test circuit chip, the test circuit chip being optically connected to the optical circuit chip, and the test circuit chip comprising: The grating coupler; the phase shifter; and The loop mirror.

4. The optical device according to claim 2, further comprising: an optical attenuator arranged between the second port and the optical circuit, wherein In the optical switch, a branching ratio between the second port and the third port is set so that return light having the same level as reflected light received from the grating coupler with respect to the input light can be obtained from the third port while the optical attenuator is controlled so that the optical attenuator blocks the input light transmitted from the second port to the optical circuit, and In the phase shifter, while controlling the optical attenuator so that the optical attenuator blocks the input light transmitted from the second port to the optical circuit, the phase shift amount of the return light transmitted to the third port is set in a direction in which the reflected light received from the grating coupler is canceled.

5. The optical device according to claim 2, wherein: The optical switch is configured by a 2×2 switch including two inputs having the first port and a fourth port and two outputs having the second port and the third port.

6. The optical device according to claim 5, wherein: The fourth port included in the optical switch is connected to an optical terminal.

7. The optical device according to claim 6, wherein: The optical termination includes an optically absorptive member.

8. The optical device according to claim 6, wherein: The optical terminal is a light detector.

9. A wafer, comprising: A plurality of optical chips, wherein Each of the optical chips comprises: Optical circuits; grating coupler; and An optical switch, comprising: a first port connected to the grating coupler; a second port connected to the optical circuit; and A third port is connected to the loop mirror through a phase shifter.

10. An optical transceiver, comprising: an optical device formed on the wafer and including an optical transmitter that transmits transmitted light according to an electrical signal; as well as A signal processing unit, wherein the signal processing unit generates the electrical signal, wherein The optical device comprises: an optical circuit, the optical circuit comprising the optical transmitter; grating coupler; and An optical switch, comprising: a first port connected to the grating coupler; a second port connected to the optical circuit; and A third port is connected to the loop mirror through a phase shifter.

11. The optical transceiver according to claim 10, wherein: The optical device includes a light receiver that converts received light into the electrical signal.

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