Optical chip, optical transmitter, optical receiver, and test system

Abstract

To provide an optical chip or the like for improving test accuracy by highly accurately measuring reflected return light to test light in an optical circuit.SOLUTION: The optical chip is an optical chip having an optical circuit disposed on a substrate. The optical chip includes a first waveguide, a second waveguide different from the first waveguide, a first edge coupler that optically connects the optical circuit and the first waveguide, and a second edge coupler that optically connects the optical circuit and the second waveguide. The waveguide length of the second waveguide is substantially equal to the waveguide length of the first waveguide.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical chip, an optical transmitter, an optical receiver, and a test system. [Background technology]

[0002] Fig. 10 is an explanatory diagram showing an example of a conventional test system 300. The test system 300 shown in Fig. 10 includes an optical chip 310 and a test apparatus 320. The test apparatus 320 includes a light source 321, a polarization controller 322, an optical power meter 323, a circulator 324, and a test fiber 325. The light source 321 is an LD (Laser Diode) that emits test light. The polarization controller 322 is a controller that controls the polarization of the test light from the light source 321. The test fiber 325 is optically connected to the optical chip 310 and is an optical fiber that inputs the polarization-adjusted test light from the polarization controller 322 and also inputs reflected return light from the optical chip 310 to the test fiber 325. The optical power meter 323 is a meter that measures the power of the reflected return light from the test fiber 325 to the test light. The circulator 324 outputs the polarization-adjusted test light from the polarization controller 322 to the test fiber 325 , and also outputs the reflected light from the test fiber 325 to the optical power meter 323 .

[0003] The optical chip 310 has a chip region 311, an optical circuit 312, a waveguide 313, and an edge coupler (EC) 314. The optical circuit 312 is, for example, a transmitting circuit or a receiving circuit mounted on the chip region 311. The waveguide 313 is, for example, an optical waveguide disposed on the chip region 311 and optically couples the optical circuit 312 and the EC 314. The EC 314 is disposed on the chip end face of the optical chip 310 and is a coupler that optically couples the waveguide 313 and the test fiber 325.

[0004] The EC 314 outputs the test light from the test fiber 325 to the optical circuit 312 to the waveguide 313, and also inputs the reflected return light of the test light from the optical circuit 312 from the waveguide 313. Furthermore, when the EC 314 inputs the reflected return light from the optical circuit 312 from the waveguide 313, it outputs the reflected return light to the test fiber 325. When the circulator 324 inputs the reflected return light from the test fiber 325, it outputs the input reflected return light to the optical power meter 323. As a result, the optical power meter 323 can measure the optical power of the reflected return light of the test light from the optical circuit 312.

[0005] 11 is an explanatory diagram showing an example of the time transition of the optical power of reflected return light with respect to the test light related to the test system 300. The optical power meter 323 identifies the end of the test fiber 325, i.e., the position of the reflected return light with respect to the test light at the EC 314, in the time-resolved optical power of the reflected return light shown in FIG. 11. Furthermore, the optical power meter 323 identifies an evaluation period of the reflected return light with respect to the test light at the waveguide 313 and the optical circuit 312 from the detection time of the reflected return light at the EC 314. The optical power meter 323 can then calculate the optical power of the reflected return light for the evaluation period by integrating the optical power of the reflected return light within the identified evaluation period.

[0006] In the test device 320, the optical chips 310 are set one by one on a test stage, and then a test fiber 325 is connected to the EC 314. However, for example, the alignment work required to connect the EC 314 at the chip end face and the test fiber 325 is troublesome, which reduces the efficiency of the work required for measurement.

[0007] Therefore, a test system capable of testing the optical chip 310 in a wafer state before being separated into chips is known. FIG. 12 is an explanatory diagram showing an example of a conventional test system 100. Note that the same components as those in the test system 300 shown in FIG. 10 are designated by the same reference numerals, and descriptions of the overlapping components and operations will be omitted. The optical chip 310A is in a wafer state before being separated into chips. The optical chip 310A in the wafer has an optical chip region 310A1 and a test region 310A2, and the boundary between the optical chip region 310A1 and the test region 310A2 can be cut along a dicing line 310C. The optical chip region 310A1 has an optical circuit 311A, a waveguide 312A, and a first EC 313A.

[0008] The test area 310A2 has a grating coupler (GC) 331, a test waveguide 332, and a second EC 333. The GC 331 is disposed on the surface of the test area 310A2 and optically connects the test fiber 325 and the test waveguide 332. The second EC 333 is disposed on the chip end face of the test area 310A2 and is an EC that optically couples with the first EC 314A. The test waveguide 332 is disposed on the test area 310A2 and is an optical waveguide that optically connects the GC 331 and the second EC 333.

[0009] The test fiber 325 is brought close to the GC 331 from the wafer surface direction, and test light from the test fiber 325 is incident on the GC 331. As a result, testing is possible in the wafer state, which improves the efficiency of the work required for measurement. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2023-91324 [Patent Document 2] U.S. Patent No. 9,459,177 [Patent Document 3] Japanese Patent Application Publication No. 2019-207305 [Patent Document 4] US Patent Application Publication No. 2020 / 0027798 Summary of the Invention [Problem to be solved by the invention]

[0011] 13 is an explanatory diagram showing an example of the time transition of the optical power of reflected return light with respect to the test light in the conventional test system 100. As shown in FIG. 13, the optical power meter 323 can sequentially measure the optical power of reflected return light with respect to the test light from the optical circuit 311A. However, the optical circuit 311A, the waveguide 312A, the first EC 313A, the second EC 333, the test waveguide 332, the GC 331, the test fiber 325, and the circulator 324 are arranged between the optical circuit 311A ​​and the optical power meter 323. Therefore, reflected return light with respect to the test light is generated in each of the optical circuit 311A, the waveguide 312A, the first EC 313A, the second EC 333, the test waveguide 332, the GC 331, the test fiber 325, and the circulator 324. As a result, it is difficult to accurately measure the optical power of the reflected return light from the optical chip area 310A1 including the optical circuit 311A ​​and the waveguide 312A in response to the test light.

[0012] In one aspect, an object of the present invention is to provide an optical chip or the like that measures reflected return light in response to test light in an optical circuit with high precision, thereby improving test precision. [Means for solving the problem]

[0013] An optical chip according to one embodiment is an optical chip having an optical circuit disposed on a substrate. The optical chip has a first waveguide, a second waveguide different from the first waveguide, a first edge coupler optically connecting the optical circuit to the first waveguide, and a second edge coupler optically connecting the second waveguide. The waveguide length of the second waveguide is approximately equal to the waveguide length of the first waveguide. [Effects of the Invention]

[0014] According to one aspect, the reflected light from the test light in the optical circuit is measured with high accuracy to improve the test accuracy. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is an explanatory diagram illustrating an example of a test system according to a first embodiment. [Figure 2] FIG. 2 is an explanatory diagram showing an example of the time transition of the optical power of the reflected return light relative to the test light related to the test system. [Figure 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 showing an example of the time transition of the optical power of the reflected return light relative to the test light related to the test system. [Figure 5] FIG. 5 is an explanatory diagram illustrating an example of a test system according to a third embodiment. [Figure 6] FIG. 6 is an explanatory diagram showing an example of the time transition of the optical power of the reflected return light relative to the test light related to the test system. [Figure 7] FIG. 7 is an explanatory diagram illustrating an example of a test system according to a fourth embodiment. [Figure 8] FIG. 8 is an explanatory diagram showing an example of the time transition of the optical power of the reflected return light with respect to the test light related to the test system. [Figure 9] FIG. 9 is an explanatory diagram illustrating an example of an optical transceiver according to this embodiment. [Figure 10] FIG. 10 is an explanatory diagram showing an example of a conventional test system. [Figure 11] FIG. 11 is an explanatory diagram showing an example of the time transition of the optical power of the reflected return light relative to the test light related to the test system. [Figure 12] FIG. 12 is an explanatory diagram showing an example of a conventional test system. [Figure 13] FIG. 13 is an explanatory diagram showing an example of the time transition of the optical power of the reflected return light relative to the test light related to the test system. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, examples of the optical chip 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 example. Furthermore, the examples shown below may be combined as appropriate within the scope of not causing any contradiction. [Example]

[0017] 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 2 on a wafer, which is a substrate, and a test apparatus 3. The test apparatus 3 includes a light source 31, a polarization controller 32, an optical power meter 33, a circulator 34, an optical switch 35, a first test fiber 36, and a second test fiber 37.

[0018] The light source 31 is an LD that emits test light. The polarization controller 32 is a controller that controls the polarization of the test light from the light source 31. The circulator 34 is connected to the polarization controller 32, the optical switch 35, and the optical power meter 33. The circulator 34 outputs the test light from the polarization controller 32 to the optical switch 35, and also outputs reflected return light of the test light from the optical switch 35 to the optical power meter 33.

[0019] The optical switch 35 optically connects to the circulator 34 and switches between the first test fiber 36 and the second test fiber 37. The optical switch 35 switches the test light from the circulator 34 to the first test fiber 36 and the second test fiber 37 and outputs the reflected return light of the test light from the first test fiber 36 and the second test fiber 37 to the circulator 34. In response to a first switching signal, the optical switch 35 switches the test light from the circulator 34 to the first test fiber 36 and outputs the first reflected return light of the test light from the first test fiber 36 to the circulator 34. In response to a second switching signal, the optical switch 35 switches the test light from the circulator 34 to the second test fiber 37 and outputs the second reflected return light of the test light from the second test fiber 37 to the circulator 34.

[0020] The first test fiber 36 is optically connected to the optical chip 2, and is an optical fiber that inputs the polarization-adjusted test light from the optical switch 35 and inputs first reflected return light from the test light from the optical chip 2 to the optical switch 35. The second test fiber 37 is optically connected to the optical chip 2, and is an optical fiber that inputs the polarization-adjusted test light from the optical switch 35 and inputs second reflected return light from the test light from the optical chip 2 to the optical switch 35. The optical power meter 33 is a meter that measures the optical power of the first reflected return light from the test light from the first test fiber 36 and also measures the optical power of the second reflected return light from the second test fiber 37 to the test light.

[0021] The optical chip 2 is in the state of a wafer before being divided into chips. The wafer has a chip area 2A and a test area 2B, and the boundary between the chip area 2A and the test area 2B can be cut along a dicing line 2C. The chip area 2A has an optical circuit 11, an edge coupler (EC) 12, a waveguide 13, and an optical mirror 14.

[0022] The optical circuit 11 is, for example, a transmitting circuit or a receiving circuit mounted on the chip area 2A. The EC 12 is arranged on the chip end surface of the chip area 2A and is a coupler that is optically connected to the waveguide 13 and optically coupled to the first EC 21 arranged in the test area 2B. The waveguide 13 is, for example, an optical waveguide that is arranged on the chip area 2A and optically couples between the optical circuit 11 and the EC 12. The optical mirror 14 is an optical device such as a loop mirror that is optically coupled to the second EC 24 in the test area 2B and reflects the test light from the second EC 24 as second reflected return light.

[0023] The test area 2B has a first EC 21, a first grating coupler (GC) 22, a first test waveguide 23, a second EC 24, a second GC 25, and a second test waveguide 26. The first EC 21 is an EC arranged on the edge face of the test area 2B of the dicing line 2C and optically connected to the first test waveguide 23 and to the EC 12 arranged on the edge face of the chip area 2A. The first GC 22 is a GC arranged on the surface of the test area 2B and optically connected to the first test fiber 36 and to the first test waveguide 23. The first test waveguide 23 is an optical waveguide that optically connects the first GC 22 and the first EC 21.

[0024] The second EC 24 is an EC that is arranged on the edge face of the test area 2B of the dicing line 2C and is optically connected to the second test waveguide 26 and also to the optical mirror 14 arranged on the edge face of the chip area 2A. The second GC 25 is a GC that is arranged on the surface of the test area 2B and is optically connected to the second test fiber 37 and also to the second test waveguide 26. The second test waveguide 26 is an optical waveguide that optically connects the second GC 25 and the second EC 24.

[0025] The waveguide length of the first test waveguide 23 between the first GC 22 and the first EC 21 is set to be approximately equal to the waveguide length of the second test waveguide 26 between the second GC 25 and the second EC 24 .

[0026] Next, the operation of the test system 1 of the first embodiment will be described. Testing begins with the optical chips 2 in a wafer state. Using an optical fiber array, the end face of the first test fiber 36 is aligned with the first GC 22, and the end face of the second test fiber 37 is aligned with the second GC 25. As a result, by aligning the end face of the first test fiber 36 with the first GC 22, an optical connection can be made between the first test fiber 36 and the first test waveguide 23. Furthermore, by aligning the end face of the second test fiber 37 with the second GC 25, an optical connection can be made between the second test fiber 37 and the second test waveguide 26.

[0027] The polarization controller 32 adjusts the polarization of the test light from the light source 31, and then outputs the polarization-adjusted test light to the circulator 34. The circulator 34 outputs the polarization-adjusted test light to the optical switch 35. The optical switch 35 outputs the polarization-adjusted test light to a first test fiber 36 and a second test fiber 37. First, the optical switch 35 switches and outputs the polarization-adjusted test light to the first test fiber 36 in response to a first switching signal.

[0028] The first GC22 outputs the test light from the first test fiber 36 to the first test waveguide 23. The first EC21 outputs the test light from the first test waveguide 23 to the EC12 in the chip area 2A. The EC12 inputs the polarization-adjusted test light from the first EC21 to the optical circuit 11 via the waveguide 13. The optical circuit 11 performs signal processing on the polarization-adjusted test light from the waveguide 13. The optical circuit 11 outputs first reflected return light of the signal-processed test light to the waveguide 13. Then, the waveguide 13 outputs the first reflected return light of the test light from the optical circuit 11 to the EC12.

[0029] The EC12 outputs the first reflected return light from the optical circuit 11 to the first EC21 in the test area 2B. The first EC21 outputs the first reflected return light from the optical circuit 11 to the first test waveguide 23. The first GC22 outputs the first reflected return light from the first test waveguide 23 to the first test fiber 36. Furthermore, the optical switch 35 outputs the first reflected return light from the first test fiber 36 to the optical power meter 33 via the circulator 34. As a result, the optical power meter 33 measures the optical power of the first reflected return light including the reflected return light from the optical circuit 11, the waveguide 13, EC12, the first EC21, the first test waveguide 23, the first GC22, the first test fiber 36, and the optical switch 35.

[0030] Furthermore, the optical switch 35 switches and outputs the polarization-adjusted test light to the second test fiber 37 in response to the second switching signal. The second GC 25 outputs the test light from the second test fiber 37 to the second test waveguide 26. The second EC 24 outputs the test light from the second test waveguide 26 to the optical mirror 14 in the chip area 2A. The optical mirror 14 reflects the test light from the second EC 24 and reflects the reflected second reflected return light to the second EC 24. The second EC 24 outputs the second reflected return light from the optical mirror 14 to the second test waveguide 26. The second GC 25 outputs the second reflected return light from the second test waveguide 26 to the second test fiber 37. Furthermore, the optical switch 35 outputs the second reflected return light from the second test fiber 37 to the optical power meter 33 via the circulator 34. As a result, the optical power meter 33 measures the optical power of the second reflected return light including the reflected return light from the optical mirror 14, the second EC 24, the second test waveguide 26, the second GC 25, the second test fiber 37, and the optical switch 35.

[0031] 2 is an explanatory diagram showing an example of the time transition of the optical power of reflected return light with respect to the test light in the test system 1. As shown in FIG. 2, the optical power meter 33 measures the optical power of the first reflected return light and the optical power of the second reflected light. The optical power of the first reflected return light includes, for example, the respective reflected lights of the test light from the optical circuit 11, the waveguide 13, the EC 12, the first EC 21, the first test waveguide 23, the first GC 22, the first test fiber 36, and the optical switch 35. The optical power of the second reflected return light includes, for example, the respective reflected lights of the test light from the optical mirror 14, the second EC 24, the second test waveguide 26, the second GC 25, the second test fiber 37, and the optical switch 35.

[0032] The optical power meter 33 compares the optical power of the first reflected return light with the optical power of the second reflected return light. The optical power meter 33 identifies the position of the second reflected return light relative to the test light at the optical mirror 14 in the time-resolved optical power of the second reflected return light shown in FIG. 2 . Furthermore, the optical power meter 33 identifies an evaluation period of the first reflected return light relative to the test light in the chip area 2A, including the EC 12, the waveguide 13, and the optical circuit 11, based on the detection time of the second reflected return light relative to the test light at the optical mirror 14. The optical power meter 33 then integrates the optical power of the first reflected return light within the identified evaluation period to calculate the optical power of the first reflected return light for the evaluation period. As a result, the optical power meter 33 can measure the first reflected return light relative to the test light in the chip area 2A with high accuracy.

[0033] In other words, since the position of reflection by the optical mirror 14 on the time axis corresponds to the position at the input stage of the chip area 2A, the optical power meter 33 can determine the area of ​​reflection within the chip area 2A based on that position, and it becomes possible to calculate the reflected return light in the chip area.

[0034] The optical chip 2 of Example 1 includes a first test waveguide 23, a second test waveguide 26, a first EC 21 optically connecting the optical circuit 11 and the first test waveguide 23, and a second EC 24 optically connecting the second test waveguide 26. The waveguide length of the second test waveguide 26 is set to be approximately equal to the waveguide length of the first test waveguide 23. The optical power meter 33 compares the optical power of the first reflected return light obtained via the first test waveguide 23 with the optical power of the second reflected return light obtained via the second test waveguide 26. Based on the comparison result, the optical power meter 33 measures the optical power of the first reflected return light in the chip area 2A with high accuracy, thereby improving test accuracy.

[0035] The optical chip 2 has an optical mirror 14 that is optically coupled to the second EC 24. As a result, it is possible to identify the detection point of the second reflected return light on the optical mirror 14 from the second reflected return light, and measure the optical power of the second reflected return light obtained via the second test waveguide 26 with high accuracy.

[0036] The optical chip 2 has a first GC 22 that optically connects the first test waveguide 23 and the first test fiber 36, and a second GC 25 that optically connects the second test waveguide 26 and the second test fiber 37. As a result, testing can be performed in the wafer state, which can improve the efficiency of work required for measurement.

[0037] The test apparatus 3 outputs test light from the first test fiber 36 to the first EC 21 via the first test waveguide 23, and obtains the optical power of the first reflected return light for the test light measured via the first EC 21. Furthermore, the test apparatus 3 outputs test light from the second test fiber 37 to the second EC 24 via the second test waveguide 26, and obtains the optical power of the second reflected return light for the test light measured via the second EC 24. Based on the comparison result between the optical power of the first reflected return light and the optical power of the second reflected return light, the test apparatus 3 measures with high accuracy the optical power of the reflected return light for the test light from the chip area 2A including the optical circuit 11. As a result, the return light for the test light in the chip area 2A including the optical circuit is measured with high accuracy, thereby improving test accuracy.

[0038] For convenience of explanation, the example has been given in which the waveguide length of the second test waveguide 26 is approximately equal to the waveguide length of the first test waveguide 23. However, this is not limitative, and the optical length of the second test waveguide 26 may be approximately equal to the optical length of the first test waveguide 23, and the same effect can be obtained.

[0039] In the optical chip 2 of Example 1, an example is given in which an optical mirror 14 is placed in the chip area 2A, but this is not limited to this, and an optical terminal may be used instead of the optical mirror 14, and this embodiment will be described below as Example 2. [Example]

[0040] 3 is an explanatory diagram showing an example of a test system 1A according to a second embodiment. The same components as those in the test system 1 according to the first embodiment are designated by the same reference numerals, and explanations of the overlapping components and operations will be omitted. The test system 1 according to the first embodiment differs from the test system 1A according to the second embodiment in that an optical terminal 15 is arranged in the chip area 2A1 instead of the optical mirror 14. The second EC 24 is an EC that is optically connected to the second test waveguide 26 and also optically connected to the optical terminal 15 arranged on the edge facet of the chip area 2A1.

[0041] The waveguide length of the first test waveguide 23 between the first GC 22 and the first EC 21 is set to be approximately equal to the waveguide length of the second test waveguide 26 between the second GC 25 and the second EC 24 .

[0042] The operation of the test system 1A of the second embodiment will be described. The second EC 24 outputs the test light from the second test waveguide 26 to the optical terminal 15. The optical terminal 15 terminates the test light from the second EC 24. As a result, the optical power meter 33 does not detect the second reflected return light from the test light from the optical terminal 15. In other words, the optical power meter 33 measures the optical power of the second reflected return light, which includes the reflected return light from the second EC 24, the second test waveguide 26, the second GC 25, the second test fiber 37, and the optical switch 35. The optical power meter 33 measures the optical power of the first reflected return light, which includes the reflected return light from the optical circuit 11, the waveguide 13, the EC 12, the first EC 21, the first test waveguide 23, the first GC 22, the first test fiber 36, and the optical switch 35.

[0043] 4 is an explanatory diagram showing an example of the time transition of the optical power of reflected return light with respect to the test light in the test system 1A. As shown in FIG. 4, the optical power meter 33 measures the optical power of the first reflected return light and the optical power of the second reflected light. The optical power of the first reflected return light includes, for example, the respective reflected lights with respect to the test light from the optical circuit 11, the waveguide 13, the EC 12, the first EC 21, the first test waveguide 23, the first GC 22, the first test fiber 36, and the optical switch 35. The optical power of the second reflected return light includes, for example, the respective reflected lights with respect to the test light from the second EC 24, the second test waveguide 26, the second GC 25, the second test fiber 37, and the optical switch 35.

[0044] The optical power meter 33 compares the optical power of the first reflected return light with the optical power of the second reflected return light. The optical power meter 33 identifies the position of the second reflected return light just before the optical terminal 15 by detecting the discontinuation of the second reflected return light at the optical terminal 15 in the time-resolved optical power of the second reflected return light shown in FIG. 4 . Furthermore, the optical power meter 33 identifies an evaluation period of the first reflected return light for the test light in the chip area 2A1, including the EC 12, the waveguide 13, and the optical circuit 11, based on the detection time of the second reflected return light for the test light just before the optical terminal 15. The optical power meter 33 then integrates the optical power of the first reflected return light within the identified evaluation period to calculate the optical power of the first reflected return light for the evaluation period. As a result, the optical power meter 33 can measure the first reflected return light for the test light in the chip area 2A1 with high accuracy.

[0045] The optical chip 2 of the second embodiment has an optical terminal 15 that is optically coupled to the second EC 24. As a result, it is possible to identify the detection point of the second reflected return light just before the optical terminal 15 from the second reflected return light, and measure the optical power of the second reflected return light obtained via the second test waveguide 26 with high accuracy.

[0046] The test apparatus 3 outputs test light from the first test fiber 36 to the first EC 21 via the first test waveguide 23, and obtains the optical power of the first reflected return light for the test light measured via the first EC 21. Furthermore, the test apparatus 3 outputs test light from the second test fiber 37 to the second EC 24 via the second test waveguide 26, and obtains the optical power of the second reflected return light for the test light measured via the second EC 24. The test apparatus 3 accurately measures the optical power of the reflected return light for the test light from the chip area 2A1 including the optical circuit 11 based on the comparison result between the optical power of the first reflected return light and the optical power of the second reflected return light. As a result, the return light for the test light in the chip area 2A1 including the optical circuit 11 is measured with high accuracy, thereby improving test accuracy.

[0047] In the test system 1 of Example 1, an example is given in which the optical mirror 14 is placed on the edge face of the chip area 2A, but this is not limited to the chip area 2A and it may also be placed in the test area 2B, and this embodiment will be described below as Example 3. [Example]

[0048] 5 is an explanatory diagram showing an example of a test system 1B according to Example 3. Note that the same components as those in the test system 1 according to Example 1 are given the same reference numerals, and descriptions of the overlapping components and operations will be omitted. The test system 1B according to Example 3 differs from the test system 1 according to Example 1 in that an optical mirror 27 is arranged in the test area 2B2 instead of the chip area 2A2.

[0049] The chip area 2A2 has an optical circuit 11, an EC 12, and a waveguide 13. The test area 2B2 has a second test waveguide 26A, a second EC 24A, and an optical mirror 27. The second test waveguide 26A is a bent waveguide that optically connects the second GC 25 and the second EC 24A. The second EC 24A is an EC that optically connects to the second test waveguide 26A and the optical mirror 27.

[0050] The waveguide length of the first test waveguide 23 between the first GC 22 and the first EC 21 is set to be approximately equal to the waveguide length of the second test waveguide 26A between the second GC 25 and the second EC 24A.

[0051] The operation of the test system 1B of Example 3 will be described. The second GC 25 outputs the test light from the second test fiber 37 to the second test waveguide 26A. The second EC 24A outputs the test light from the second test waveguide 26A to the optical mirror 27. The optical mirror 27 receives the test light from the second EC 24A and outputs it to the second EC 24A as second reflected return light of the test light. The second EC 24A outputs the second reflected return light from the optical mirror 27 to the second test waveguide 26A. The second GC 25 outputs the second reflected return light from the second test waveguide 26A to the second test fiber 37.

[0052] Furthermore, the optical switch 35 outputs the second reflected return light from the second test fiber 37 to the optical power meter 33 via the circulator 34. That is, the optical power meter 33 measures the optical power of the second reflected return light including the reflected return light from, for example, the optical mirror 27, the second EC 24A, the second test waveguide 26A, the second GC 25, the second test fiber 37, and the optical switch 35. The optical power meter 33 also measures the optical power of the first reflected return light including the reflected return light from the optical circuit 11, the waveguide 13, the EC 12, the first EC 21, the first test waveguide 23, the first GC 22, the first test fiber 36, and the optical switch 35.

[0053] 6 is an explanatory diagram showing an example of the time transition of the optical power of the reflected return light with respect to the test light in the test system 1B. As shown in FIG. 6, the optical power meter 33 measures the optical power of the first reflected return light and the optical power of the second reflected light. The optical power of the first reflected return light includes, for example, the respective reflected lights of the test light from the optical circuit 11, the waveguide 13, the EC 12, the first EC 21, the first test waveguide 23, the first GC 22, the first test fiber 36, and the optical switch 35. The optical power of the second reflected return light includes, for example, the respective reflected lights of the test light from the optical mirror 27, the second EC 24, the second test waveguide 26, the second GC 25, the second test fiber 37, and the optical switch 35.

[0054] The optical power meter 33 compares the optical power of the first reflected return light with the optical power of the second reflected return light. The optical power meter 33 identifies the position of the second reflected return light at the optical mirror 27 in the time-resolved optical power of the second reflected return light shown in FIG. 6. Furthermore, the optical power meter 33 identifies an evaluation period of the first reflected return light for the test light in the chip area 2A2, including the EC 12, the waveguide 13, and the optical circuit 11, based on the detection time of the second reflected return light for the test light at the optical mirror 27. The optical power meter 33 then integrates the optical power of the first reflected return light within the identified evaluation period to calculate the optical power of the first reflected return light for the evaluation period. As a result, the optical power meter 33 can measure the first reflected return light for the test light in the chip area 2A2 with high accuracy.

[0055] The optical chip 2 of Example 3 has an optical mirror 27 optically coupled to the second EC 24A. As a result, the detection location of the second reflected return light at the optical mirror 27 can be identified from the second reflected return light, and the optical power of the second reflected return light obtained via the second test waveguide 26A can be measured with high accuracy. Moreover, since the optical mirror 27 is arranged in the test area 2B2, the chip area 2A2 can be made smaller.

[0056] The test apparatus 3 outputs test light from the first test fiber 36 to the first EC 21 via the first test waveguide 23, and obtains the optical power of the first reflected return light for the test light measured via the first EC 21. Furthermore, the test apparatus 3 outputs test light from the second test fiber 37 to the second EC 24A via the second test waveguide 26A, and obtains the optical power of the second reflected return light for the test light measured via the second EC 24A. Based on the comparison result between the optical power of the first reflected return light and the optical power of the second reflected return light, the test apparatus 3 measures with high accuracy the optical power of the reflected return light for the test light from the chip area 2A2 including the optical circuit 11. As a result, the return light for the test light in the chip area 2A2 including the optical circuit 11 is measured with high accuracy, thereby improving test accuracy.

[0057] For convenience of explanation, the example has been given in which the waveguide length of the second test waveguide 26A is approximately equal to the waveguide length of the first test waveguide 23. However, this is not limitative, and the optical length of the second test waveguide 26A may be approximately equal to the optical length of the first test waveguide 23, with the same effect being obtained.

[0058] In the test system 1 of Example 1, a case where the first test fiber 36 and the second test fiber 37 are used is exemplified, but a single test fiber may also be used, and this embodiment will be described below as Example 4. [Example]

[0059] 7 is an explanatory diagram showing an example of a test system 1C of Example 4. Note that the same components as those in the test system 1B of Example 3 are given the same reference numerals, and descriptions of the overlapping components and operations will be omitted. The difference between the test system 1B of Example 3 and the test system 1C of Example 4 is that a single test fiber 36A optically connects the test device 3A and the test area 2B3.

[0060] The test apparatus 3A includes a light source 31, a polarization controller 32, an optical power meter 33, a circulator 34, and one test fiber 36A. The test fiber 36A is an optical fiber that optically connects the circulator 34 and the GC 22A in the test area 2B3.

[0061] The test area 2B3 includes a GC 22A, a first EC 21, a second EC 24A, a first test waveguide 23B, a second test waveguide 26B, a test common waveguide 28, an optical switch 29, and an optical mirror 27. The GC 22A is optically connected to the test fiber 36A and the test common waveguide 28. The optical switch 29 is optically connected to the test common waveguide 28 and to the first test waveguide 23B and the second test waveguide 26B. In response to a first switching signal, the optical switch 29 switches the test light from the test common waveguide 28 to the first test waveguide 23B and outputs the first reflected return light of the test light from the first test waveguide 23B to the test common waveguide 28. In addition, in response to the second switching signal, the optical switch 29 switches and outputs the test light from the test common waveguide 28 to the second test waveguide 26B, and also switches and outputs the second reflected return light of the test light from the second test waveguide 26B to the test common waveguide 28.

[0062] The first test waveguide 23B is an optical waveguide that optically connects the optical switch 29 and the first EC 21. The first EC 21 is disposed on the edge face near the dicing line 2C of the test area 2B3, and is optically connected to the EC 12 in the chip area 2A3. The second test waveguide 26B is a bent waveguide that optically connects the optical switch 29 and the second EC 24A. The second EC 24A is an EC that optically connects to the second test waveguide 26B and also to the optical mirror 27.

[0063] The waveguide length of the first test waveguide 23B between the optical switch 29 and the first EC 21 is set to be approximately equal to the waveguide length of the second test waveguide 26B between the optical switch 29 and the second EC 24A.

[0064] Next, a description will be given of the operation of the test system 1C of the fourth embodiment. Testing is started when the optical chip 2 is in the wafer state. The end face of the test fiber 36A is aligned with the GC 22A, thereby optically connecting the test fiber 36A and the test common waveguide 28.

[0065] The polarization controller 32 adjusts the polarization of the test light from the light source 31, and then outputs the polarization-adjusted test light to the circulator 34. The circulator 34 outputs the polarization-adjusted test light to a test fiber 36A.

[0066] The GC22A in the test area 2B3 outputs the test light from the test fiber 36A to the test common waveguide 28. The optical switch 29 in the test area 2B3 outputs the test light from the test common waveguide 28 to the first test waveguide 23B in response to the first switching signal. The first EC21 outputs the test light from the first test waveguide 23B to the EC12 in the chip area 2A3. The EC12 inputs the polarization-adjusted test light from the first EC21 to the optical circuit 11 via the waveguide 13. The optical circuit 11 performs signal processing on the polarization-adjusted test light from the waveguide 13. The optical circuit 11 outputs first reflected return light of the signal-processed test light to the waveguide 13. Then, the waveguide 13 outputs the first reflected return light of the test light from the optical circuit 11 to the EC12.

[0067] The EC12 outputs the first reflected return light from the optical circuit 11 to the first EC21. The first EC21 outputs the first reflected return light from the optical circuit 11 to the first test waveguide 23B. The optical switch 29 outputs the first reflected return light from the first test waveguide 23B to the test common waveguide 28. Furthermore, the GC22A outputs the first reflected return light from the test common waveguide 28 to the test fiber 36A. The circulator 34 outputs the first reflected return light from the test fiber 36A to the optical power meter 33. That is, the optical power meter 33 measures the optical power of the first reflected return light, which includes the light reflected from each of the optical circuit 11, the waveguide 13, EC12, the first EC21, the first test waveguide 23B, the optical switch 29, and the test common waveguide 28 with respect to the test light.

[0068] The second EC 24A outputs the test light from the second test waveguide 26B to the optical mirror 27 in the test area 2B3. The optical mirror 27 receives the test light from the second EC 24A and reflects and outputs second reflected return light of the test light to the second EC 24A. The second EC 24A outputs the second reflected return light from the optical mirror 27 to the second test waveguide 26B. The optical switch 29 outputs the second reflected return light from the second test waveguide 26B to the test common waveguide 28. Furthermore, the GC 22A outputs the second reflected return light from the test common waveguide 28 to the test fiber 36A. The circulator 34 outputs the second reflected return light from the test fiber 36A to the optical power meter 33. As a result, the optical power meter 33 measures the optical power of the second reflected return light, which includes the respective reflected lights of the test light from, for example, the optical mirror 27, the second EC 24A, the second test waveguide 26B, the optical switch 29, and the test common waveguide 28.

[0069] 8 is an explanatory diagram showing an example of the time transition of the optical power of reflected return light with respect to the test light in the test system 1C. As shown in FIG. 8, the optical power meter 33 measures the optical power of the first reflected return light and the optical power of the second reflected light. The optical power of the first reflected return light includes, for example, the respective reflected lights of the test light from the optical circuit 11, the waveguide 13, the EC 12, the first EC 21, the first test waveguide 23B, the optical switch 29, and the test common waveguide 28. The optical power of the second reflected return light includes, for example, the respective reflected lights of the test light from the optical mirror 27, the second EC 24A, the second test waveguide 26B, the optical switch 29, and the test common waveguide 28.

[0070] The optical power meter 33 compares the optical power of the first reflected return light with the optical power of the second reflected return light. The optical power meter 33 identifies the position of the second reflected return light at the optical mirror 27 in the time-resolved optical power of the second reflected return light shown in FIG. 8 . Furthermore, the optical power meter 33 identifies an evaluation period of the first reflected return light for the test light in the chip area 2A3, including the EC 12, the waveguide 13, and the optical circuit 11, based on the detection time of the second reflected return light for the test light at the optical mirror 27. The optical power meter 33 then integrates the optical power of the first reflected return light within the identified evaluation period to calculate the optical power of the first reflected return light for the evaluation period. As a result, the optical power meter 33 can measure the first reflected return light for the test light in the chip area 2A3 with high accuracy.

[0071] In the test area 2B3 of the optical chip 2 of Example 4, an optical switch 29 is disposed to switch between the test common waveguide 28 connected to the GC 22A connected to the test fiber 36A and the first test waveguide 23B, and between the test common waveguide 28 and the second test waveguide 26B. As a result, a single test fiber 36A is sufficient, and the connection configuration between the test equipment 3A and the test area 2B3 can be simplified. Moreover, the optical switch 29 in the test area 2B3 can be used to switch between the first reflected return light and the second reflected return light.

[0072] The test device 3A outputs test light from the test fiber 36A to the first EC 21 via the first test waveguide 23B and obtains the optical power of the first reflected return light for the test light measured via the first EC 21. Furthermore, the test device 3A outputs the test light from the test fiber 36A to the second EC 24A via the second test waveguide 26B and obtains the optical power of the second reflected return light for the test light measured via the second EC 24A. Based on the comparison result between the optical power of the first reflected return light and the optical power of the second reflected return light, the test device 3A measures with high accuracy the optical power of the reflected return light for the test light from the chip area 2A3 including the optical circuit 11. As a result, the return light for the test light in the chip area 2A3 including the optical circuit 11 is measured with high accuracy, thereby improving test accuracy.

[0073] For convenience of explanation, the example has been given in which the waveguide length of the second test waveguide 26B is approximately equal to the waveguide length of the first test waveguide 23B. However, this is not limiting, and the optical length of the second test waveguide 26B may be approximately equal to the optical length of the first test waveguide 23B, and the same effect can be obtained.

[0074] FIG. 9 is an explanatory diagram illustrating an example of an optical transceiver 70 according to this embodiment. The optical transceiver 70 shown in FIG. 9 is connected to an output optical fiber and an input optical fiber. The optical transceiver 70 includes a DSP (Digital Signal Processor) 72 and an optical transmitter / receiver 73. The optical transmitter / receiver 73 includes an optical transmitter 73A and an optical receiver 73B. The DSP 72 is an electrical component that performs digital signal processing. For example, the DSP 72 performs processing such as encoding transmission data, generates an electrical signal containing the transmission data, and outputs the generated electrical signal to the optical transmitter 73A. The DSP 72 also acquires an electrical signal containing reception data from the optical receiver 73B and performs processing such as decoding the acquired electrical signal to obtain the reception data.

[0075] The optical transmitter 73A has an optical modulator element 73A1 that modulates supplied light with an electrical signal output from the DSP 72, and outputs the transmission light modulated by the electrical signal to an optical fiber. The optical modulator element 73A1 has a built-in optical device that guides the light to be output to the optical fiber.

[0076] The optical receiver 73B has an optical receiver element 73B1 that receives an optical signal from an optical fiber and demodulates the received light using the supplied light, converts the demodulated received light into an electrical signal, and outputs the converted electrical signal to the DSP 72.

[0077] For ease of explanation, the optical chip 2 is exemplified as incorporating both a transmitting circuit and a receiving circuit, but it may also incorporate only one of the transmitting circuit and the receiving circuit; if it incorporates only a transmitting circuit, it becomes an optical transmitter, and if it incorporates only a receiving circuit, it becomes an optical receiver.

[0078] In addition, the optical fiber array may be fixed on a wafer prober, and the wafer mounted on the wafer prober may move up, down, left, and right relative to the optical fiber array, or the optical fiber array may move up, down, left, and right on the wafer, and modifications may be made as appropriate.

[0079] Furthermore, the components of each unit shown in the figure do 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.

[0080] 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 MCU (Micro Controller Unit)). Needless to say, 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 MCU), or on hardware using wired logic. [Explanation of symbols]

[0081] 1 Test System 2 Optical chip 2A chip area 2B Test Area 2C dicing line 3 Test equipment 11 Optical circuit 14 Light mirror 15 Optical Termination 21 First EC 22 First GC 23 First test waveguide 24 Second EC 25 Second GC 26 Second test waveguide 29 Optical Switch 36 First test fiber 37 Second test fiber

Claims

1. An optical chip having an optical circuit disposed on a substrate, a first waveguide; and a second waveguide different from the first waveguide; a first edge coupler that optically connects the optical circuit and the first waveguide; a second edge coupler optically connected to the second waveguide; The waveguide length of the second waveguide is an optical chip having a waveguide length substantially equal to that of the first waveguide;

2. 2. The optical chip according to claim 1, further comprising an optical mirror that optically couples with the second edge coupler.

3. 2. The optical chip according to claim 1, further comprising an optical termination for optically coupling with the second edge coupler.

4. a first grating coupler that optically connects the first waveguide and a first optical fiber; a second grating coupler that optically connects the second waveguide and a second optical fiber; 2. The optical chip according to claim 1, further comprising:

5. The second waveguide comprises:

2. The optical chip according to claim 1, further comprising a curved waveguide.

6. a grating coupler for optically connecting to an optical fiber; an optical switch that switches between the first waveguide and the second waveguide and connects the grating coupler; 2. The optical chip according to claim 1, further comprising:

7. The optical chip is The semiconductor device has a first region and a second region, and is configured in a state where the first region and the second region are connected across a dicing line, The first region includes: The optical circuit is provided. The second region is 2. The optical chip according to claim 1, comprising the first waveguide, the second waveguide, the first edge coupler, and the second edge coupler.

8. An optical transmitter comprising an optical chip having an optical circuit disposed on a substrate, the optical chip having an optical modulation element in the optical circuit, The optical chip comprises: a first waveguide; and a second waveguide different from the first waveguide; a first edge coupler that optically connects the optical circuit and the first waveguide; a second edge coupler optically connected to the second waveguide; The waveguide length of the second waveguide is an optical transmitter having a waveguide length substantially equal to that of the first waveguide;

9. 1. An optical receiver comprising an optical chip having an optical circuit disposed on a substrate, the optical chip having an optical receiving element in the optical circuit, The optical chip comprises: a first waveguide; and a second waveguide different from the first waveguide; a first edge coupler that optically connects the optical circuit and the first waveguide; a second edge coupler optically connected to the second waveguide; The waveguide length of the second waveguide is an optical receiver, characterized in that the waveguide length of the first waveguide is approximately equal to that of the second waveguide;

10. A test system comprising: an optical chip having an optical circuit disposed on a substrate; and a test device that transmits test light to the optical circuit via an optical fiber and measures the power of return light from the optical circuit via the optical fiber in response to the test light, The optical chip comprises: a first waveguide optically connected to the optical fiber; a second waveguide different from the first waveguide, optically connected to the optical fiber; a first edge coupler that optically connects the optical circuit and the first waveguide; a second edge coupler optically connected to the second waveguide; The waveguide length of the second waveguide is The waveguide length is approximately equal to that of the first waveguide, The test device comprises: A test system characterized by transmitting the test light from the optical fiber to the first edge coupler via the first waveguide and measuring a first return light power for the test light via the first edge coupler, and transmitting the test light from the optical fiber to the second edge coupler via the second waveguide and measuring a second return light power for the test light from the optical circuit based on the first return light power for the test light measured via the first edge coupler.

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