Optical device, wafer and optical transceiver

Abstract

To provide an optical device etc., capable of obtaining reflected return light, corresponding to light, of an optical circuit with high precision.SOLUTION: The optical device, which is formed on a wafer, comprises: an optical circuit; a grating coupler; and an optical switch which 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.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical device, a wafer, and an optical transceiver. [Background technology]

[0002] Fig. 9 is an explanatory diagram showing an example of a conventional test system 200. The test system 200 shown in Fig. 9 includes a test apparatus 210, an optical chip 220, and an optical fiber 230. The test apparatus 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 test light corresponding to, for example, received light, local light, or transmitted light. The polarization controller 212 polarizes the test light from the light source 211 and outputs the polarized test light to the circulator 213. The polarization controller 212 controls the polarization of the test light to generate TM polarized or TM polarized test light. The circulator 213 outputs the test light incident from the polarization controller 212 to the optical fiber 230, and outputs reflected return light of the test light incident from the optical fiber 230 to the power meter 214. The power meter 214 receives the reflected return light of the test light 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 transceiver. The optical chip 220 is an optical chip cut out from a wafer. The optical chip 220 has an optical port 221, an optical circuit 222, and an optical waveguide 223. The optical port 221 is exposed at a side end of the optical chip 220 by forming the wafer into chips. The optical waveguide 223 is a waveguide that guides light between the optical port 221 and the optical circuit 222. The optical circuit 222 is, for example, a circuit such as an optical transmitter or an optical receiver of a digital coherent optical transceiver.

[0005] In a conventional method for testing optical chip 220, optical chips 220 are cut out from a wafer, and each individual optical chip 220 is placed on a stage. Furthermore, an optical fiber 230 is connected between the output of circulator 213 of test device 210 and optical port 221 at the end of the side surface of optical chip 220. Then, test device 210 uses power meter 214 to measure the power of the reflected light relative to the test light, and evaluates optical chip 220 from the measurement result.

[0006] However, in the conventional method for testing the optical chip 220, it is necessary to perform an alignment work for aligning the optical axis between the optical port 221 and the optical fiber 230 for each optical chip 220. As a result, the workload becomes large when optically connecting the optical chip 220 and the test device 210 and measuring the power of the reflected return light for the test light.

[0007] In addition, it is conceivable that the work efficiency would be improved if the optical chips 220 could be tested in the wafer state before being made into chips, but when testing is performed in the wafer state, it is necessary to input light from the wafer surface direction using an optical fiber. Therefore, a test system 100 that employs such a test method will be described.

[0008] Fig. 8 is an explanatory diagram showing an example of a conventional test system 100. The test system 100 includes a wafer, such as silicon, on which a plurality of optical chips 110 are formed, a test device 210, and an optical fiber 230. Note that the same components as those in the test device 210 shown in Fig. 9 are given the same reference numerals, and descriptions of the overlapping components and operations will be omitted.

[0009] A plurality of optical chips 110 are formed on the wafer in a lattice arrangement. The optical chip 110 has an optical circuit chip 110A, a test circuit chip 110B, and a dicing line 110C that can be cut between the optical circuit chip 110A and the test circuit chip 110B. The optical circuit chip 110A has an optical port 111A, an optical circuit 112A, and a first optical waveguide 113A that optically couples the optical port 111A and the optical circuit 112A. The optical port 111A is exposed at the side end of the optical chip 220 by forming the wafer into chips. The optical circuit 112A is, for example, a circuit such as an optical transmitter or an optical receiver in a digital coherent optical transceiver. The first optical waveguide 113A is a waveguide that guides light between the optical port 111A and the optical circuit 112A.

[0010] The test circuit chip 110B has a GC (Grating Coupler) 111B and a second optical waveguide 112B. The GC 111B is disposed on the surface of the test circuit chip 110B, and is detachably connected to the optical fiber 230 and is connected to the second optical waveguide 112B. The second optical waveguide 112B is optically connected to the optical port 111A in the optical circuit chip 110A.

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

[0012] Next, the operation of the test system 100 will be described. The polarization controller 212 in the test device 210 polarizes the test light 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 on the test circuit chip 110B inputs the test light from the optical fiber 230 to the second optical waveguide 112B. Furthermore, the optical circuit chip 110A inputs the test light from the optical port 111A connected to the second optical waveguide 112B, and inputs the input 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 reflected return light of 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 from the first optical waveguide 113A to the optical fiber 230 via the GC 111B. Furthermore, the circulator 213 outputs the reflected return light 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 from the circulator 213. In the test system 100, the optical fiber 230 is brought close to the GC 11B from the wafer surface direction to input light, and the test light can be input to the optical circuit 112A, making it possible to perform testing in the wafer state. The test device 210 evaluates the optical circuit chip 110A based on the measurement result of the reflected return light from the optical circuit 112A. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] US Patent Application Publication No. 2022 / 0065743 [Patent Document 2] JP 2020-181076 A [Patent Document 3] JP 2020-72345 A Summary of the Invention [Problem to be solved by the invention]

[0016] The test device 210 of the conventional test system 100 measures the reflected return light from the optical circuit 112A. However, in the test device 210, reflected light of the test light is generated at the GC 111B connected to the optical fiber 230, so the measured value of the reflected return light includes the reflected light of the test light from the GC 111B. As a result, it is difficult to obtain the reflected return light from the optical circuit 112A with high accuracy.

[0017] One object of the present invention is to provide an optical device or the like that can obtain highly accurate return light reflected from an optical circuit in response to light. [Means for solving the problem]

[0018] An optical device according to one embodiment is an optical device formed on a wafer, the optical device including an optical circuit, a grating coupler, and an optical switch having 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 via a phase shifter. Effect of the Invention

[0019] According to one aspect, it is possible to obtain highly accurate reflected return light of an optical circuit with respect to light. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is an explanatory diagram illustrating an example of a test system according to a first embodiment. [Diagram 2] FIG. 2 is a plan view showing an example of a wafer on which optical chips are formed. [Diagram 3] FIG. 3 is an explanatory diagram illustrating an example of a test system according to the second embodiment. [Figure 4] FIG. 4 is an explanatory diagram illustrating an example of a test system according to a third embodiment. [Diagram 5] FIG. 5 is an explanatory diagram illustrating an example of a test system according to a fourth embodiment. [Figure 6] FIG. 6 is an explanatory diagram illustrating an example of a test system according to a fifth embodiment. [Figure 7] FIG. 7 is an explanatory diagram showing an example of an optical transceiver equipped with an optical chip. [Figure 8] FIG. 8 is an explanatory diagram showing an example of a conventional test system. [Figure 9] FIG. 9 is an explanatory diagram showing an example of a conventional test system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, examples of the optical device and the like disclosed in the present application will be described in detail with reference to the drawings. Note that the disclosed technology is not limited to each of the examples. In addition, each of the examples shown below may be appropriately combined as long as no contradiction occurs. EXAMPLES

[0022] Fig. 1 is an explanatory diagram showing an example of a test system 1 according to a first embodiment. The test system 1 shown in Fig. 1 includes an optical chip 3, a test device 2, and an optical fiber 4 that optically connects the optical chip 3 and the test device 2. The optical chip 3 is, for example, an optical IC chip that implements an optical circuit such as a digital coherent optical transceiver. The test device 2 is an evaluation device that evaluates the optical chip 3.

[0023] Fig. 2 is a plan view showing an example of a wafer 5 on which optical chips 3 are formed. The wafer 5 shown in Fig. 2 is, for example, a silicon wafer. A plurality of optical chips 3 are formed on the wafer 5 in a lattice-like arrangement. The optical chip 3 is an optical device having an optical circuit chip 3A, a test circuit chip 3B, and a dicing line 3C that can cut between the optical circuit chip 3A and the test circuit chip 3B.

[0024] The optical circuit chip 3A has an optical port 22, an optical circuit 21, and a first optical waveguide 23 that optically connects the optical port 22 and the optical circuit 21. The optical port 22 is exposed at a side end of the optical circuit chip 3A by forming the wafer 5 into a chip. The optical circuit 21 is, for example, a circuit such as an optical transmitter or an optical receiver in a digital coherent optical transceiver. The first optical waveguide 23 is a waveguide that guides light between the optical port 22 and the optical circuit 21.

[0025] The test circuit chip 3B has a GC (Grating Coupler) 31, an optical switch 32, a second optical waveguide 33, a PS (Phase Shifter) 34, and a loop mirror 35. The GC 31 is disposed on the surface of the test circuit chip 3B, and is detachably connected to an optical fiber 4 connected to the test device 2, and is also connected to the optical switch 32. The optical switch 32 is configured as a 1×2 optical switch having one input port and two output ports. The optical switch 32 has 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 and outputs the test light from the GC 31 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 that is optically connected to the optical port 22 of the optical circuit chip 3 A. The optical switch 32 sets the branching ratio of the second port 32 B and the third port 32 C so that test light having the same level as the reflected light of the test light from the GC 31 is obtained from the third port 32 C.

[0026] The role of PS34 is to generate the return light of the test light from the third port 32C as a cancellation light of the opposite phase so as to cancel the reflected light of the test light from GC31. PS34 changes the phase of the test light from the third port 32C of the optical switch 32 by 180 degrees in the direction of canceling the reflected light of the test light from GC31. PS34 transmits the test light input from the third port 32C and outputs it to the loop mirror 35. Then, the loop mirror 35 returns the test light input from PS34 to PS34 by bypassing it. Then, PS34 changes the phase of the test light input from the loop mirror 35 to the opposite phase of the reflected light, and outputs the test light after the phase change as return light to the third port 32C in the optical switch 32.

[0027] 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 test light. The polarization controller 12 polarizes the test light from the light source 11, and outputs the polarized test light to the circulator 13. The circulator 13 outputs the polarized test light from the polarization controller 12 to the optical fiber 4. The circulator 13 receives the reflected return light from the optical circuit 21 input from the second port 32B, and outputs the reflected return light to the power meter 14. The reflected return light with respect to the test light is the reflected return light of the optical circuit 21 with respect to the test light. The power meter 14 measures the power of the reflected return light from the circulator 13. The test device 2 evaluates the optical circuit chip 3A based on the measurement result of the reflected return light by the power meter 14.

[0028] The optical switch 32 outputs the return light input from the third port 32C and the reflected return light of the test light from the optical circuit 21 input from the second port 32B to the circulator 13 in the test equipment 2 via the GC 31 and the optical fiber 4. The circulator 13 can obtain the reflected return light from the optical circuit 21 input from the second port 32B with high accuracy by canceling out the reflected light of the test light from the GC 31 and the return light input from the third port 32C. Then, the circulator 13 outputs the reflected return light to the power meter 14 in the test equipment 2.

[0029] Next, the operation of the test system 1 of this embodiment will be described. First, the wafer 5 is placed on the wafer prober. Then, the test circuit chip 3B in the optical chip 3 on the wafer 5 moves, and the test operation starts in a state where the GC 31 in the test circuit chip 3B and the optical fiber 4 are optically connected.

[0030] The polarization controller 12 polarizes the test light from the light source 11, and inputs the polarized test light to the circulator 13. The circulator 13 outputs the polarized test light to the optical fiber 4. The GC 31 connected to the optical fiber 4 outputs the input polarized test light to the optical switch 32. The optical switch 32 inputs the polarized test light from a first port 32A, and branches and outputs the polarized test light to a second port 32B and a third port 32C.

[0031] The optical switch 32 outputs the polarized test light from the second port 32B to the second optical waveguide 33, and outputs the polarized test light to the optical port 22 of the optical circuit chip 3A. The optical circuit chip 3A inputs the polarized test light from the optical port 22 to the first optical waveguide 23. The optical circuit 21 in the optical circuit chip 3A inputs the polarized test light from the first optical waveguide 23, and outputs reflected return light for the polarized test light to the first optical waveguide 23. The second optical waveguide 33 in the test circuit chip 3B inputs the reflected return light from the optical port 22 to the second port 32B in the optical switch 32.

[0032] Furthermore, when the optical switch 32 branches and outputs the polarized test light 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 PS34. The PS34 outputs the test light input from the third port 32C to the loop mirror 35. The loop mirror 35 returns the test light input from the PS34 to the PS34 as return light. The PS34 then adjusts the phase of the return light input from the loop mirror 35, and inputs the phase-adjusted return light to the third port 32C of the optical switch 32. The phase-adjusted return light is light that cancels out the reflected light of the test light from the GC31.

[0033] The optical switch 32 multiplexes the reflected return light input from the second port 32B and the phase-adjusted return light input from the third port 32C, and outputs the reflected return light including the multiplexed return light to the GC 31. The GC 31 also generates reflected light in response to the test light from the circulator 13.

[0034] Then, the circulator 13 receives the return reflected light including the return light from the first port 32A of the optical switch 32 and the reflected light generated by the GC 31, and outputs only the return reflected light to the power meter 14 by canceling out the reflected light with the return light. The power meter 14 measures the power of the reflected return light. The test device 2 can evaluate the optical circuit chip 3A based on the measurement result of the power meter 14.

[0035] Then, when the test device 2 has completed the measurement and evaluation operation of the power of the reflected return light of the optical circuit chips 3A in all the optical chips 3 in the row unit on the wafer 5 shown in Fig. 2, it dices all the optical chips 3 in the row unit along the dicing lines 3C. Then, it starts the measurement operation of the reflected return light for each optical chip 3 in the next row unit, and continues until the measurement operation of all the optical chips 3 on the wafer 5 is completed. Also, by dicing along the dicing lines 3C for each optical chip 3 of the wafer 5, the optical circuit chip 3A and the test circuit chip 3B in the optical chip 3 are separated, and the optical circuit chip 3A can be obtained.

[0036] The optical chip 3 includes an optical circuit 21, a GC 31, and an optical switch 32 having 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 a loop mirror 35 via a PS 34. The optical switch 32 sets the branching ratios of the second port 32B and the third port 32C so that return light having the same level as the reflected light from the GC 31 with respect to the test light is obtained from the third port 32C. The PS 34 is set to a phase shift amount of the return light to the third port 32C in a direction to cancel the reflected light from the GC 31. In other words, the branching ratio of the optical switch 32 and the phase shift amount of the PS 34 are adjusted in advance so that the reflected light from the GC 31 and the return light from the PS 34 cancel each other out, so that the test device 2 can measure the reflected return light from the optical circuit 21 with high accuracy by suppressing the reflected light generated by the GC 31. As a result, by suppressing the reflected light from the GC 31, the optical circuit chip 3A can be accurately evaluated based on the measurement result of the reflected return light from the optical circuit 21.

[0037] By optically connecting the optical chip 3 and the test device 2, the work efficiency can be improved when measuring the power of the reflected light relative to the test light.

[0038] For ease of explanation, the case has been exemplified in which PS34 adjusts the phase of the return light from the loop mirror 35 and inputs the phase-adjusted return light to the third port 32C of the optical switch 32. However, this is not limited to this, and PS34 adjusts the phase of the test light input from the third port 32C, outputs the phase-adjusted test light to the loop mirror 35, and outputs the test light returned from the loop mirror 35 to PS34 as return light. PS34 may also transmit the return light input from the loop mirror 35 and input it to the third port 32C, and this can be changed as appropriate. EXAMPLES

[0039] 3 is an explanatory diagram showing an example of a test system 1A of the embodiment 2. The same components as those in the test system 1 of the embodiment 1 are denoted by the same reference numerals, and the description of the overlapping components and operations will be omitted. The test system 1A of the embodiment 2 differs from the test system 1 of the embodiment 1 in that the test system 1A of the embodiment 2 has a test circuit chip 3B1 in which a variable optical attenuator (VOA) 36 is arranged on the second optical waveguide 33 between the first optical waveguide 23 and the optical switch 32.

[0040] The VOA 36 transmits the test light from the second port 32B to the optical circuit 21, and then blocks the test light from the second port 32B to the optical circuit 21. Then, the PS 34 adjusts and sets in advance the amount of phase shift of the test light to the third port 32C in a direction to cancel the reflected light input to the GC 31 while the VOA 36 blocks the test light. The optical switch 32 also adjusts and sets in advance the optical branching ratios of the second port 32B and the third port 32C in a direction to cancel the reflected light input to the GC 31 while the VOA 36 blocks the test light.

[0041] The branching ratio of the second port 32B and the third port 32C of the optical switch 32 is set so that return light of the same level as the reflected light from GC 31 is obtained from the third port 32C in a state where the test light from the second port 32B to the optical circuit 21 is blocked by the VOA 36. The phase shift amount of the return light to the third port 32C of the PS34 is set in a direction to cancel the reflected light from GC 31 in a state where the test light from the second port 32B to the optical circuit 21 is blocked. As a result, the phase shift amount of the PS34 and the branching ratio of the optical switch 32 can be set with high accuracy to cancel the reflected light from GC 31.

[0042] In the first embodiment, the optical switch 32 in the test circuit chip 3B in the test system 1 is configured as a 1×2 switch. However, components other than the reflected return light input from the second port 32B and the return light input from the third port 32C become radiated light. As a result, the radiated light returns to the optical circuit 21 and GC 31 and becomes noise, degrading the measurement accuracy of the reflected return light. Therefore, an embodiment for dealing with such a situation will be described below as a third embodiment. EXAMPLES

[0043] 4 is an explanatory diagram showing an example of a test system 1B of Example 3. The same components as those in the test system 1 of Example 1 are given the same reference numerals, and explanations of the overlapping components and operations are omitted. The difference between the test system 1 of Example 1 and the test system 1B of Example 3 is that the test system 1B of Example 3 has a test circuit chip 3B2 that employs an optical switch 37 of 2×2 configuration instead of the optical switch 32 of 1×2 configuration.

[0044] The optical switch 37 is configured as a 2×2 optical switch having two input ports and two output ports. The input ports in the optical switch 37 include a first port 37A connected to the GC 31 and a fourth port 37D. The output ports 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 from the GC 31 to the second port 37B and the third port 37C based on a branching ratio set in advance. The branching ratios of the second port 37B and the third port 37C are set so that test light having the same level as the reflected light of the test light from the GC 31 is obtained from the third port 37C. The branching ratios of the first port 37A and the fourth port 37D of the optical switch 37 are equal to the branching ratios of the second port 37B and the third port 37C. Furthermore, since the optical switch 37 is a 2×2 optical switch, the radiated light generated by the 1×2 optical switch 32 can be suppressed.

[0045] The test circuit chip 3B2 can suppress the generation of radiated light by employing the 2×2 optical switch 37. As a result, the test device 2 can improve the measurement accuracy of the reflected return light from the optical circuit 21. EXAMPLES

[0046] FIG. 5 is an explanatory diagram showing an example of a test system 1B1 of the fourth embodiment. The same components as those of the test system 1B of the third embodiment are given the same reference numerals, and the description of the overlapping components and operations is omitted. The test system 1B of the third embodiment differs from the test system 1B1 of the fourth embodiment in that an optical terminal 38 is optically connected to a fourth port 37D of a 2×2 optical switch 37. The optical terminal 38 is, for example, a light absorbing member that absorbs light. The light absorbing member may be, for example, a metal or semiconductor thin film, or Si doped with a metal.

[0047] Since the optical switch 37 optically connects the optical terminal 38 to the fourth port 37D, the light flowing out from the fourth port 37D is optically absorbed by the optical terminal 38. As a result, the test device 2 aims to improve the measurement accuracy of the reflected return light from the optical circuit 21. EXAMPLES

[0048] FIG. 6 is an explanatory diagram showing an example of a test system 1B2 of the fifth embodiment. The same components as those of the test system 1B1 of the fourth embodiment are given the same reference numerals, and the description of the overlapping components and operations is omitted. The test system 1B1 of the fourth embodiment differs from the test system 1B2 of 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. Furthermore, the PD 39 connects the photoelectrically converted electric signal to a monitor, monitors a part of the reflected return light with the PD 39, and correlates it with the value of the power meter 14, thereby realizing highly accurate measurement of the reflected return light.

[0049] Since the fourth port 37D is optically connected to the PD 39, the light flowing out from the fourth port 37D is absorbed by the PD 39. As a result, in the test device 2, the measurement accuracy of the reflected return light from the optical circuit 21 is improved.

[0050] FIG. 7 is an explanatory diagram showing an example of an optical transceiver 50 in which an optical chip 3 is mounted. The optical transceiver 50 shown in FIG. 7 includes an LD (Laser Diode) 51, a DSP (Digital Signal Processor) 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. The optical transceiver 50 includes an optical transmitter 53A that transmits a signal light, and an optical receiver 53B that receives the signal light. The optical receiver 53B is the optical circuit chip 3A after disconnecting a test circuit chip 3B such as a digital coherent receiver that converts the signal light into an electrical signal. The DSP 52 digitally converts each electrical signal input from the optical receiver 53B. The optical transmitter 53A is the optical circuit chip 3A after disconnecting a test circuit chip 3B such as a digital coherent transmitter that modulates light according to an electrical signal from the DSP 52.

[0051] For convenience of explanation, the optical fiber 4 is fixed on a 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 move up, down, left and right on the wafer 5, and other suitable modifications can be made.

[0052] Further, the optical circuit chip 3A is exemplified as a digital coherent transceiver, but is not limited to the digital coherent system, and may be an optical receiver or an optical transmitter of another system, and can be modified as appropriate.

[0053] Furthermore, each component of each unit shown in the figure does not necessarily have to be physically configured as shown in the figure. In other words, the specific form of distribution and integration of each unit is not limited to that shown in the figure, and all or part of them can be functionally or physically distributed and integrated in any unit depending on various loads, usage conditions, etc.

[0054] Furthermore, the various processing functions performed by each device may be executed in whole or in part on a CPU (Central Processing Unit) (or a microcomputer such as an MPU (Micro Processing Unit) or an MCU (Micro Controller Unit)). It goes without saying that the various processing functions may be executed in whole or in part on a program analyzed and executed by a CPU (or a microcomputer such as an MPU or an MCU), or on hardware using wired logic.

[0055] The following supplementary notes are further disclosed regarding the above-described embodiments including the present example.

[0056] (Appendix 1) An optical device formed on a wafer, An optical circuit; A grating coupler; an optical switch having 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 via a phase shifter; An optical device comprising:

[0057] (Additional Note 2) The optical switch is inputting input light from the first port, and setting a branching ratio between the second port and the third port so that, when the input light input from the first port is branched and output to the second port and the third port, a return light having the same level as a reflected light from the grating coupler with respect to the input light is obtained from the third port; The phase shifter comprises: 2. The optical device according to claim 1, wherein a phase shift amount of the return light to the third port is set in a direction to cancel out the reflected light from the grating coupler.

[0058] (Appendix 3) The optical device is an optical circuit chip on which the optical circuit is mounted, and a test circuit chip optically connected to the optical circuit chip; The test circuit chip includes: The grating coupler; The phase shifter; The loop mirror; 3. The optical device according to claim 2, comprising:

[0059] (Supplementary Note 4) Further comprising an optical attenuator disposed between the second port and the optical circuit; The optical switch comprises: a branching ratio between the second port and the third port is set so that, in a state in which the optical attenuator is controlled so as to block the input light from the second port to the optical circuit, a return light having the same level as a reflected light from the grating coupler with respect to the input light is obtained from the third port; The phase shifter comprises: 3. The optical device of claim 2, wherein a phase shift amount of the return light to the third port is set in a direction to cancel out the reflected light from the grating coupler in a state in which the optical attenuator is controlled so as to block the input light from the second port to the optical circuit.

[0060] (Supplementary Note 5) The optical switch is 3. The optical device of claim 2, comprising a 2×2 switch including two inputs, the first port and the fourth port, and two outputs, the second port and the third port.

[0061] (Supplementary Note 6) The fourth port in the optical switch is 6. The optical device of claim 5, which is connected to an optical termination.

[0062] (Supplementary Note 7) The optical terminal 7. The optical device according to claim 6, comprising a light absorbing member.

[0063] (Supplementary Note 8) The optical terminal 7. The optical device according to claim 6, which is a photodetector.

[0064] (Appendix 9) Optical circuit and A grating coupler; an optical switch having 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 via a phase shifter.

[0065] (Supplementary Note 10) An optical transceiver comprising: an optical device formed on a wafer, the optical device including an optical transmitter for transmitting a transmission light in response to an electrical signal; and a signal processing unit for generating the electrical signal, The optical device comprises: an optical circuit including the optical transmitter; A grating coupler; an optical switch having 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 via a phase shifter; 1. An optical transceiver comprising:

[0066] (Supplementary Note 11) The optical device is 11. The optical transceiver of claim 10, further comprising an optical receiver that converts received light into an electrical signal. [Explanation of symbols]

[0067] 2. Test Equipment 3 Optical chip 3A Optical Circuit Chip 3B Test circuit chip 21 Optical circuit 31 GC 32 Optical Switch 32A 1st port 32B Second Port 32C 3rd port 34 PS 35 Loop Mirror 37 Optical Switch 37A 1st port 37B Second Port 37C Third Port 37D 4th Port

Claims

1. An optical device formed on a wafer, An optical circuit; A grating coupler; 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 a loop mirror via a phase shifter; An optical device comprising:

2. The optical switch comprises: inputting input light from the first port, and setting a branching ratio between the second port and the third port so that, when the input light input from the first port is branched and output to the second port and the third port, a return light having the same level as a reflected light from the grating coupler with respect to the input light is obtained from the third port; The phase shifter comprises:

2. The optical device according to claim 1, wherein an amount of phase shift of the returning light to the third port is set in a direction to cancel the reflected light from the grating coupler.

3. The optical device comprises: an optical circuit chip on which the optical circuit is mounted, and a test circuit chip optically connected to the optical circuit chip; The test circuit chip includes: The grating coupler; The phase shifter; The loop mirror; 3. The optical device according to claim 2, further comprising:

4. an optical attenuator disposed between the second port and the optical circuit; The optical switch comprises: a branching ratio between the second port and the third port is set so that, in a state in which the optical attenuator is controlled so as to block the input light from the second port to the optical circuit, a return light having the same level as a reflected light from the grating coupler with respect to the input light is obtained from the third port; The phase shifter comprises:

3. The optical device according to claim 2, wherein a phase shift amount of the return light to the third port is set in a direction to cancel out the reflected light from the grating coupler while the optical attenuator is controlled so as to block the input light from the second port to the optical circuit.

5. The optical switch comprises:

3. The optical device according to claim 2, comprising a 2.times.2 switch including two inputs, the first port and a fourth port, and two outputs, the second port and a third port.

6. The fourth port in the optical switch 6. The optical device according to claim 5, further comprising an optical termination.

7. The optical terminal comprises:

7. The optical device according to claim 6, further comprising a light absorbing member.

8. The optical terminal comprises:

7. The optical device according to claim 6, which is a photodetector.

9. An optical circuit; A grating coupler; an optical switch having 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 via a phase shifter.

10. An optical transceiver comprising: an optical device formed on a wafer, the optical device including an optical transmitter that transmits a transmission light in response to an electrical signal; and a signal processing unit that generates the electrical signal, The optical device comprises: an optical circuit including the optical transmitter; A grating coupler; 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 a loop mirror via a phase shifter; 1. An optical transceiver comprising:

Images