Phase shifter array and optical phased array

Abstract

To provide a phase shifter array and an optical phased array for suppressing an increase in the size of a control unit.SOLUTION: A phase shifter array of an optical phased array has a sub-array 300 that includes a first phase shifter 301, a second phase shifter 302, and a third phase shifter 303. The first phase shifter 301 changes the phase of light as a first voltage V1 from a DAC 20 is applied, and the second phase shifter 302 changes the phase of light as a second voltage V2 from the DAC 20 is applied. The third phase shifter 303 includes a first shifter unit 311 to which the first voltage V1 is applied, a second shifter unit 312 to which the second voltage V2 is applied, and an insulating layer 313 for insulating between the first shifter unit 311 and the second shifter unit 312. The third phase shifter 303 changes the phase of light as the first voltage V1 is applied to the first shifter unit 311 and the second voltage V2 is applied to the second shifter unit 312.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to phase shifter arrays and optical phased arrays. [Background technology]

[0002] Conventionally, as described in Patent Document 1, an optical phased array is known that includes a subarray in which a plurality of phase shifters that change the phase of incident light are grouped together. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Pat. No. 10,613,410 Summary of the Invention [Problem to be solved by the invention]

[0004] In the optical phased array described in Patent Document 1, a voltage signal for changing the phase of light incident on a phase shifter is output from a control unit to each phase shifter in one subarray. Therefore, when the number of phase shifters in one subarray increases, the number of voltage signals from the control unit increases accordingly, and the number of wirings, etc., in the control unit increases. Therefore, the control unit becomes larger.

[0005] The present disclosure aims to provide a phase shifter array and an optical phased array that suppress an increase in size of a control unit. [Means for solving the problem]

[0006] The invention described in claim 1 is a phase shifter array, comprising at least one subarray (300) having a first phase shifter (301), a second phase shifter (302) arranged in line with the first phase shifter, and at least one third phase shifter (303) arranged in line with the first phase shifter and the second phase shifter between the first phase shifter and the second phase shifter, and the first phase shifter is turned on by applying a first voltage (V1) from a control unit (20) that applies a voltage to the subarray. the second phase shifter changes the phase of the light incident on it by applying a second voltage (V2) from the control unit; the third phase shifter includes a first shifter section (311) to which a first voltage is applied and a second shifter section (312) to which a second voltage is applied, and the third phase shifter is a phase shifter array that changes the phase of the light incident on the third phase shifter by applying the first voltage to the first shifter section and the second voltage to the second shifter section.

[0007] The invention described in claim 8 is an optical phased array including a splitter tree (10) that splits incident light (Li) into a plurality of lights, a control unit (20) that applies a voltage, a phase shifter array (30) that changes the phase of the light from the splitter tree by applying a voltage from the control unit, and an antenna array (70) that emits light at an angle according to the phase of the light changed by the phase shifter array, wherein the phase shifter array includes a first phase shifter (301), a second phase shifter (302) arranged side by side with the first phase shifter, and at least one third phase shifter arranged side by side with the first phase shifter and the second phase shifter between the first phase shifter and the second phase shifter. The optical phased array has at least one subarray (300) including a first phase shifter section (311) to which the first voltage is applied and a second shifter section (312) to which the second voltage is applied, and the third phase shifter is an optical phased array that changes the phase of light incident on the third phase shifter by applying the first voltage to the first shifter section and the second voltage to the second shifter section.

[0008] As a result, the number of voltages output from the control unit to one subarray becomes two. Therefore, the number of voltages from the control unit is twice N, which corresponds to the total number of phase shifters, divided by S, which corresponds to the number of third phase shifters in one subarray, plus two, i.e., 2×N / (S+2). Therefore, even if the number of phase shifters increases, the number of third phase shifters increases, so an increase in the number of voltages from the control unit is suppressed. Therefore, an increase in the number of wirings, etc. in the control unit is suppressed, and the size of the control unit is suppressed.

[0009] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and specific components described in the embodiments described below. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a configuration diagram of an optical phased array including a phase shifter array according to a first embodiment. [Diagram 2] FIG. 1 is a configuration diagram of a subarray of a phase shifter array. [Diagram 3] FIG. 13 is a configuration diagram of a subarray when the number of third phase shifters is two. [Figure 4] FIG. [Diagram 5] Cross-sectional view of line VV in Figure 4. [Figure 6] Cross-sectional view taken along line VI-VI in Figure 4. [Figure 7] Cross-sectional view taken along line VII-VII in Figure 4. [Figure 8] Cross-sectional view taken along line VIII-VIII in Figure 4. [Figure 9] Cross-sectional view of line IX-IX in Figure 4. [Figure 10] Cross-sectional view taken along line XX in Figure 4. [Figure 11] Cross-sectional view taken along line XI-XI in Figure 4. [Figure 12] Cross-sectional view of line XII-XII in Figure 4. [Figure 13] Cross-sectional view taken along line XIII-XIII in Figure 4. [Figure 14] Cross-sectional view taken along line XIV-XIV in Figure 4. [Figure 15] 4A and 4B are diagrams for explaining phase differences in a phase shifter array; [Figure 16] 4A and 4B are diagrams for explaining an emission angle and a radiation angle. [Figure 17] FIG. 11 is a configuration diagram for explaining generation of a first table and a second table in an optical phased array according to a second embodiment. [Figure 18] FIG. 13 is a configuration diagram of an optical phased array according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals, and the description thereof will be omitted.

[0012] (First embodiment) The optical phased array including the phase shifter array of the present embodiment is used in, for example, Lidar, where the size of the control unit is suppressed. Note that Lidar is an abbreviation for Light Detection and Ranging / Laser Imaging Detection and Ranging.

[0013] Specifically, as shown in FIG. 1 , the optical phased array 5 includes a splitter tree 10, a DAC 20, a phase shifter array 30, and an antenna array 70.

[0014] The splitter tree 10 splits incident light Li from a light source (not shown) into N light beams by using multiple splitters 100 that split light. For example, splitters 100 that split light into two are connected in series. In this way, the splitter tree 10 splits incident light Li into N light beams. As described later, N is a natural number equal to or greater than 3.

[0015] The DAC 20 corresponds to a control unit, and applies a voltage to a phase shifter array 30, which will be described later. Note that DAC is an abbreviation for Digital-to-Analog Converter.

[0016] The phase shifter array 30 changes the phase of the light from the splitter tree 10. Specifically, the phase shifter array 30 has at least one subarray 300 and a semiconductor substrate 400, which will be described later.

[0017] Here, a plurality of subarrays 300 are arranged. Each subarray 300 includes one first phase shifter 301, one second phase shifter 302, and at least one third phase shifter 303, as shown in FIG.

[0018] The first phase shifter 301 extends in a direction from the splitter tree 10 through the phase shifter array 30 toward the antenna array 70, which will be described later. Furthermore, a first voltage V1 from the DAC 20 is applied to the first phase shifter 301. This causes the first phase shifter 301 to change the phase of the light incident on the first phase shifter 301 from the splitter tree 10. The detailed structure of the first phase shifter 301 will be described later.

[0019] The second phase shifter 302 extends in a direction from the splitter tree 10 through the phase shifter array 30 toward the antenna array 70 (described later), and is aligned with the first phase shifter 301. A second voltage V2 from the DAC 20 is applied to the second phase shifter 302. This causes the second phase shifter 302 to change the phase of the light incident on the second phase shifter 302 from the splitter tree 10. The detailed structure of the second phase shifter 302 will be described later.

[0020] The third phase shifter 303 is arranged between the first phase shifter 301 and the second phase shifter 302, together with the first phase shifter 301 and the second phase shifter 302. The third phase shifter 303 also has a first shifter portion 311, a second shifter portion 312, and an insulating layer 313.

[0021] The first shifter section 311 and the second shifter section 312 extend in a direction from the splitter tree 10 through the phase shifter array 30 toward the antenna array 70 described below. Furthermore, a first voltage V1 is applied to the first shifter section 311. Furthermore, a second voltage V2 is applied to the second shifter section 312. As a result, the third phase shifter 303 changes the phase of the light incident on the third phase shifter 303 from the splitter tree 10. Therefore, the first phase shifter 301, the second phase shifter 302, and the third phase shifter 303 cause the number of branches of the splitter tree 10 to be three or more, so N is set to a natural number of three or more.

[0022] The insulating layer 313 corresponds to an insulating portion and has electrical insulation properties. Furthermore, the insulating layer 313 insulates between the first shifter portion 311 and the second shifter portion 312. The detailed structure of the third phase shifter 303 will be described later.

[0023] Here, the direction in which the first phase shifter 301 and the second phase shifter 302 are lined up is the parallel direction Dp. Also, the number of third phase shifters 303 is S. Furthermore, here, S is 2 or more, and a plurality of third phase shifters 303 are lined up in the parallel direction Dp. The length of the first phase shifter 301 is La(0). The length of the second phase shifter 302 is Lb(0). Furthermore, the lengths of the first shifter sections 311 are La(1), La(2), La(3), . . . , La(S-1), La(S) in order from the third phase shifter 303 adjacent to the first phase shifter 301 to the third phase shifter 303 adjacent to the second phase shifter 302. Also, the lengths of the second shifter sections 312 are denoted as Lb(1), Lb(2), Lb(3), . . . , Lb(S-1), and Lb(S) in the order from the third phase shifter 303 adjacent to the first phase shifter 301 to the third phase shifter 303 adjacent to the second phase shifter 302. In this case, the sum of the lengths of the first shifter sections 311 and the second shifter sections 312 corresponding to each other is expressed as La(S)+Lb(S). Note that the lengths of the first phase shifter 301, the second phase shifter 302, the first shifter section 311, and the second shifter section 312 are lengths in the direction from the splitter tree 10 through the phase shifter array 30 toward the antenna array 70 described later.

[0024] Furthermore, the distance from the center of the first phase shifter 301 to the center of the second phase shifter 302 in the parallel direction Dp is defined as Ws. Also, the distances from the first phase shifter 301 to the third phase shifter 303 in the parallel direction Dp are defined as D(1), . . . , D(S) in order from the third phase shifter 303 adjacent to the first phase shifter 301 to the third phase shifter 303 adjacent to the second phase shifter 302. Note that the distance from the first phase shifter 301 to the third phase shifter 303 in the parallel direction Dp is, for example, the distance from the center of the first phase shifter 301 to the center of the third phase shifter 303 in the parallel direction Dp.

[0025] And, La(0), Lb(0), and La(S)+Lb(S) are equal to Ls, that is, La(0)=Lb(0)=La(S)+Lb(S)=Ls. Note that "equal" here includes the manufacturing error range.

[0026] Moreover, La(1), La(2), La(3), . . ., La(S-2), La(S-1), and La(S) are smaller in order, that is, La(1)>La(2)>La(3)> . . .>La(S-2)>La(S-1)>La(S). Furthermore, Lb(1), Lb(2), Lb(3), . . ., Lb(S-2), Lb(S-1), and Lb(S) are larger in order, that is, Lb(1). <Lb(2)<Lb(3)<···<Lb(S-2)<Lb(S-1)<Lb(S)とされている。

[0027] Moreover, La(S) is a value obtained by subtracting D(s) from Ws and dividing the result by Ws, as shown in the following relational expression (1). Furthermore, Lb(S) is a value obtained by dividing D(s) by Ws, as shown in the following relational expression (2).

[0028]

number

[0029] 3, for example, S corresponding to the number of third phase shifters 303 is set to 2. Furthermore, the distance from the center of the first phase shifter 301 to the center of the third phase shifter 303 adjacent to the first phase shifter 301 in the parallel direction Dp is set to d1. Furthermore, the distance from the center of the third phase shifter 303 adjacent to the first phase shifter 301 in the parallel direction Dp to the center of the third phase shifter 303 adjacent to the second phase shifter 302 in the parallel direction Dp is set to d2. Furthermore, the distance from the center of the third phase shifter 303 adjacent to the second phase shifter 302 in the parallel direction Dp to the center of the second phase shifter 302 is set to d3.

[0030] In this case, D(1) is d1. Furthermore, D(2) is d1+d2. Furthermore, Ws is d1+d2+d3. Therefore, La(1), La(2), Lb(1), and Lb(2) are expressed by the following relational expressions (3) to (6).

[0031]

number

[0032] Returning to FIG. 1 , the antenna array 70 has N antennas 700. Light whose phase has been changed by the phase shifter array 30 is incident on the antenna 700. The antenna 700 further includes a diffraction grating and the like. As a result, the antenna array 70 emits light at an angle according to the phase of the light changed by the phase shifter array 30.

[0033] As described above, the optical phased array 5 including the phase shifter array 30 of the first embodiment is configured. Next, the structures of the first phase shifter 301, the second phase shifter 302, and the third phase shifter 303 will be described in detail with reference to Figs. 4 to 14. In order to make these structures easier to understand, it is assumed that S=2.

[0034] The first phase shifter 301, the second phase shifter 302, and the third phase shifter 303 are formed on a semiconductor substrate 400 such as an SOI substrate. Note that SOI is an abbreviation for Silicon on Insulator.

[0035] Moreover, the first phase shifter 301 has a first waveguide 421 , a first electrode 431 , a second electrode 432 , a first wiring 441 and a second wiring 442 .

[0036] Light incident on the first phase shifter 301 propagates through the first waveguide 421. The first waveguide 421 is formed from an active layer of the semiconductor substrate 400, and is, for example, a silicon waveguide having a PN junction. The first waveguide 421 is covered by a BOX 410 of the semiconductor substrate 400 and a first interlayer insulating film 411. The BOX is an abbreviation for Buried OXide, and means a buried insulating film.

[0037] Specifically, as shown in FIG. 5, first waveguide 421 includes a first rib portion 451, a second rib portion 452, a first connection portion 461, a second connection portion 462, a first contact portion 471, and a second contact portion 472.

[0038] The first rib portion 451 is of N-type. The first rib portion 451 extends in one direction in the surface direction of the semiconductor substrate 400. For example, in FIG. 4, the left-right direction of the paper corresponds to one direction. The thickness direction of the semiconductor substrate 400 is simply referred to as the thickness direction. Furthermore, here, the direction perpendicular to the one direction and the thickness direction is referred to as the width direction. The width direction corresponds to the direction intersecting with the thickness direction.

[0039] Returning to FIG. 5, the second rib portion 452 is P-type. Furthermore, the second rib portion 452 extends in one direction. Furthermore, the second rib portion 452 is joined to the first rib portion 451 in the width direction. This forms a PN junction. Furthermore, the thickness of the second rib portion 452 is equal to the thickness of the first rib portion 451.

[0040] The first connection portion 461 is made of N-type ferroelectric material having a higher impurity concentration than the first rib portion 451. + The first connection portion 461 is connected in the width direction to the side of the first rib portion 451 opposite to the second rib portion 452. The thickness of the first connection portion 461 is smaller than the thickness of the first rib portion 451.

[0041] The second connection portion 462 is made of P + The second connection portion 462 is connected in the width direction to the second rib portion 452 on the opposite side to the first rib portion 451. The thickness of the second connection portion 462 is smaller than the thickness of the second rib portion 452.

[0042] The first contact portion 471 is an N-type semiconductor having a higher impurity concentration than the first connection portion 461. ++ The first contact portion 471 is connected in the width direction to the side of the first connection portion 461 opposite to the first rib portion 451. The thickness of the first contact portion 471 is set to be equal to the thickness of the first connection portion 461, for example. Therefore, the thickness of the first contact portion 471 is set to be smaller than the thickness of the first rib portion 451.

[0043] The second contact portion 472 is a P ++ The second contact portion 472 is connected in the width direction to the side of the second connection portion 462 opposite to the second rib portion 452. The thickness of the second contact portion 472 is set to be equal to the thickness of the second connection portion 462, for example. Therefore, the thickness of the second contact portion 472 is set to be smaller than the thickness of the second rib portion 452.

[0044] The first electrode 431 extends in one direction and also in the thickness direction. The first electrode 431 includes a first via hole 501, a first via 551, a first electrode layer 601, a second via hole 502, a second via 552, and a second electrode layer 602.

[0045] The first via hole 501 is connected to the first contact portion 471. Furthermore, the first via hole 501 is covered with the first interlayer insulating film 411.

[0046] The first via 551 is formed of a metal such as tungsten. Moreover, the first via 551 is embedded in the first via hole 501, and is thereby connected to the first contact portion 471 in the thickness direction. Furthermore, the first via 551 is covered with the first interlayer insulating film 411.

[0047] The first electrode layer 601 is formed of a metal such as aluminum. The first electrode layer 601 is connected to the first via 551 in the thickness direction. The first electrode layer 601 is covered with the second interlayer insulating film 412. The second interlayer insulating film 412 is formed on the first interlayer insulating film 411.

[0048] The second via hole 502 is connected to the first electrode layer 601. Furthermore, the second via hole 502 is covered with the second interlayer insulating film 412.

[0049] The second via 552 is formed of a metal such as tungsten. The second via 552 is embedded in the second via hole 502, and is thereby connected to the first electrode layer 601 in the thickness direction. The second via 552 is covered with the second interlayer insulating film 412.

[0050] The second electrode layer 602 is formed of a metal such as aluminum. The second electrode layer 602 is connected to the second via 552 in the thickness direction. The second electrode layer 602 is covered with a third interlayer insulating film 413. The third interlayer insulating film 413 is formed on the second interlayer insulating film 412.

[0051] The second electrode 432 extends in one direction and also in the thickness direction. The second electrode 432 includes a third via hole 503, a third via 553, a third electrode layer 603, a fourth via hole 504, a fourth via 554, and a fourth electrode layer 604.

[0052] The third via hole 503 is connected to the second contact portion 472. Furthermore, the third via hole 503 is covered with the first interlayer insulating film 411.

[0053] The third via 553 is formed of a metal such as tungsten. The third via 553 is embedded in the third via hole 503, and is thereby connected to the second contact portion 472 in the thickness direction. The third via 553 is covered with the first interlayer insulating film 411.

[0054] The third electrode layer 603 is formed of a metal such as aluminum. The third electrode layer 603 is connected to the third via 553 in the thickness direction. The third electrode layer 603 is covered with the second interlayer insulating film 412.

[0055] The fourth via hole 504 is connected to the third electrode layer 603. Furthermore, the fourth via hole 504 is covered with the second interlayer insulating film 412.

[0056] The fourth via 554 is formed of a metal such as tungsten. The fourth via 554 is embedded in the fourth via hole 504, and is thereby connected to the third electrode layer 603 in the thickness direction. The fourth via 554 is covered with the second interlayer insulating film 412.

[0057] The fourth electrode layer 604 is formed of a metal such as aluminum. The fourth electrode layer 604 is connected to the fourth via 554 in the thickness direction. The fourth electrode layer 604 is covered with the third interlayer insulating film 413.

[0058] The first wiring 441 includes a first wiring layer 651 , a fifth via hole 505 , a fifth via 555 , and a second wiring layer 652 .

[0059] The first wiring layer 651 is formed of a metal such as aluminum. The first wiring layer 651 is connected to a part of the second electrode layer 602 in the width direction, and extends in the width direction from the boundary with the second electrode layer 602. The first wiring layer 651 is covered with the third interlayer insulating film 413.

[0060] The fifth via hole 505 is connected to the first wiring layer 651. Furthermore, the fifth via hole 505 is covered with the third interlayer insulating film 413.

[0061] The fifth via 555 is formed of a metal such as tungsten. The fifth via 555 is embedded in the fifth via hole 505, and is thereby connected to the first wiring layer 651 in the thickness direction. The fifth via 555 is covered with the third interlayer insulating film 413.

[0062] The second wiring layer 652 is formed of a metal such as aluminum. The second wiring layer 652 is connected to the fifth via 555 in the thickness direction. The second wiring layer 652 is formed on the third interlayer insulating film 413, and is therefore exposed to the outside of the third interlayer insulating film 413. The second wiring layer 652 is connected to a DAC.

[0063] As shown in FIG. 14, the second wiring 442 includes a third wiring layer 653, a sixth via hole 506, a sixth via 556, and a fourth wiring layer 654.

[0064] The third wiring layer 653 is formed of a metal such as aluminum. The third wiring layer 653 is connected to a part of the fourth electrode layer 604 in the width direction, and extends in the width direction from the boundary with the fourth electrode layer 604. The third wiring layer 653 is covered with the third interlayer insulating film 413.

[0065] The sixth via hole 506 is connected to the third wiring layer 653. Furthermore, the sixth via hole 506 is covered with the third interlayer insulating film 413.

[0066] The sixth via 556 is formed of a metal such as tungsten. The sixth via 556 is embedded in the sixth via hole 506, and is thereby connected to the third wiring layer 653 in the thickness direction. The sixth via 556 is covered with the third interlayer insulating film 413.

[0067] The fourth wiring layer 654 is formed of a metal such as aluminum. The fourth wiring layer 654 is connected to the sixth via 556 in the thickness direction. The fourth wiring layer 654 is formed on the third interlayer insulating film 413, and is exposed to the outside of the third interlayer insulating film 413. The fourth wiring layer 654 is connected to the DAC 20. As described above, the second wiring layer 652 is connected to the DAC 20. Therefore, the first phase shifter 301 is electrically connected to the DAC 20.

[0068] 4 and other drawings, the second phase shifter 302 has a second waveguide 422, a third electrode 433, a fourth electrode 434, a third wiring 443, and a fourth wiring 444. In FIG. 4, the third wiring 443 and the fourth wiring 444 are indicated by dashed lines in order to easily distinguish them from the first wiring 441 and the second wiring 442.

[0069] The light incident on the second phase shifter 302 propagates through the second waveguide 422. Furthermore, the second waveguide 422 is formed from an active layer of the semiconductor substrate 400, and is, for example, a silicon waveguide having a PN junction. Moreover, the second waveguide 422 is covered with the BOX 410 of the semiconductor substrate 400 and the first interlayer insulating film 411.

[0070] Specifically, as shown in FIG. 5, second waveguide 422 includes a third rib portion 453, a fourth rib portion 454, a third connecting portion 463, a fourth connecting portion 464, a third contact portion 473, and a fourth contact portion 474.

[0071] The third rib portion 453 is N-shaped. The third rib portion 453 extends in one direction.

[0072] The fourth rib portion 454 is P-type. Furthermore, the fourth rib portion 454 extends in one direction. Furthermore, the fourth rib portion 454 is joined to the third rib portion 453 in the width direction. This forms a PN junction. Furthermore, the thickness of the fourth rib portion 454 is equal to the thickness of the third rib portion 453.

[0073] The third connection portion 463 is made of N-type ferroelectric material having a higher impurity concentration than the third rib portion 453. + The third connection portion 463 is connected in the width direction to the side of the third rib portion 453 opposite to the fourth rib portion 454. The thickness of the third connection portion 463 is smaller than the thickness of the third rib portion 453.

[0074] The fourth connection portion 464 is made of a P + The fourth connection portion 464 is connected in the width direction to the side of the fourth rib portion 454 opposite to the third rib portion 453. The thickness of the fourth connection portion 464 is smaller than the thickness of the fourth rib portion 454.

[0075] The third contact portion 473 is an N-type semiconductor having a higher impurity concentration than the third connection portion 463. ++ The third contact portion 473 is connected in the width direction to the side of the third connection portion 463 opposite to the third rib portion 453. The thickness of the third contact portion 473 is set to be equal to the thickness of the third connection portion 463, for example. Therefore, the thickness of the third contact portion 473 is set to be smaller than the thickness of the third rib portion 453.

[0076] The fourth contact portion 474 is a P ++ The fourth contact portion 474 is connected in the width direction to the side of the fourth connection portion 464 opposite to the fourth rib portion 454. The thickness of the fourth contact portion 474 is set to be equal to the thickness of the fourth connection portion 464, for example. Therefore, the thickness of the fourth contact portion 474 is set to be smaller than the thickness of the fourth rib portion 454.

[0077] The third electrode 433 extends in one direction and also in the thickness direction. The third electrode 433 includes a seventh via hole 507, a seventh via 557, and a fifth electrode layer 605.

[0078] The seventh via hole 507 is connected to the third contact portion 473. Furthermore, the seventh via hole 507 is covered with the first interlayer insulating film 411.

[0079] The seventh via 557 is formed of a metal such as tungsten. The seventh via 557 is embedded in the seventh via hole 507, and is thereby connected to the third contact portion 473 in the thickness direction. The seventh via 557 is covered with the first interlayer insulating film 411.

[0080] The fifth electrode layer 605 is formed of a metal such as aluminum. The fifth electrode layer 605 is connected to the seventh via 557 in the thickness direction. The fifth electrode layer 605 is covered with the second interlayer insulating film 412.

[0081] The fourth electrode 434 extends in one direction and also in the thickness direction. The fourth electrode 434 includes an eighth via hole 508, an eighth via 558, and a sixth electrode layer 606.

[0082] The eighth via hole 508 is connected to the fourth contact portion 474. Furthermore, the eighth via hole 508 is covered with the first interlayer insulating film 411.

[0083] The eighth via 558 is formed of a metal such as tungsten. The eighth via 558 is embedded in the eighth via hole 508, and is thereby connected to the fourth contact portion 474 in the thickness direction. The eighth via 558 is covered with the first interlayer insulating film 411.

[0084] The sixth electrode layer 606 is formed of a metal such as aluminum. The sixth electrode layer 606 is connected to the eighth via 558 in the thickness direction. The sixth electrode layer 606 is covered with the second interlayer insulating film 412.

[0085] The third wiring 443 includes a fifth wiring layer 655 , a ninth via hole 509 , a ninth via 559 , a sixth wiring layer 656 , a tenth via hole 510 , a tenth via 560 , and a seventh wiring layer 657 .

[0086] The fifth wiring layer 655 is formed of a metal such as aluminum. The fifth wiring layer 655 is connected to a part of the fifth electrode layer 605 in the width direction, and extends in the width direction from the boundary with the fifth electrode layer 605. The fifth wiring layer 655 is covered with the second interlayer insulating film 412.

[0087] The ninth via hole 509 is connected to the fifth wiring layer 655. Furthermore, the ninth via hole 509 is covered with the second interlayer insulating film 412.

[0088] The ninth via 559 is formed of a metal such as tungsten. The ninth via 559 is embedded in the ninth via hole 509, and is thereby connected to the fifth wiring layer 655 in the thickness direction. The ninth via 559 is covered with the second interlayer insulating film 412.

[0089] The sixth wiring layer 656 is formed of a metal such as aluminum. The sixth wiring layer 656 is connected to the ninth via 559 in the thickness direction. The sixth wiring layer 656 is covered with the third interlayer insulating film 413.

[0090] The tenth via hole 510 is connected to the sixth wiring layer 656. Furthermore, the tenth via hole 510 is covered with the third interlayer insulating film 413.

[0091] The tenth via 560 is formed of a metal such as tungsten. The tenth via 560 is embedded in the tenth via hole 510, and is thereby connected to the sixth wiring layer 656 in the thickness direction. The tenth via 560 is covered with the third interlayer insulating film 413.

[0092] The seventh wiring layer 657 is formed of a metal such as aluminum. The seventh wiring layer 657 is connected to the tenth via 560 in the thickness direction. The seventh wiring layer 657 is formed on the third interlayer insulating film 413, and is therefore exposed to the outside of the third interlayer insulating film 413. The seventh wiring layer 657 is connected to the DAC 20.

[0093] As shown in FIG. 14, the fourth wiring 444 includes an eighth wiring layer 658, an eleventh via hole 511, an eleventh via 561, a ninth wiring layer 659, a twelfth via hole 512, a twelfth via 562, and a tenth wiring layer 660.

[0094] The eighth wiring layer 658 is formed of a metal such as aluminum. The eighth wiring layer 658 is connected to a part of the sixth electrode layer 606 in the width direction, and extends in the width direction from the boundary with the sixth electrode layer 606. The eighth wiring layer 658 is covered with the second interlayer insulating film 412.

[0095] The eleventh via hole 511 is connected to the eighth wiring layer 658. Furthermore, the eleventh via hole 511 is covered with the second interlayer insulating film 412.

[0096] The eleventh via 561 is formed of a metal such as tungsten. The eleventh via 561 is embedded in the eleventh via hole 511, and is thereby connected to the eighth wiring layer 658 in the thickness direction. The eleventh via 561 is covered with the second interlayer insulating film 412.

[0097] The ninth wiring layer 659 is formed of a metal such as aluminum. The ninth wiring layer 659 is connected to the eleventh via 561 in the thickness direction. The ninth wiring layer 659 is covered with the third interlayer insulating film 413.

[0098] The twelfth via hole 512 is connected to the ninth wiring layer 659. Furthermore, the twelfth via hole 512 is covered with the third interlayer insulating film 413.

[0099] The twelfth via 562 is formed of a metal such as tungsten. The twelfth via 562 is buried in the twelfth via hole 512, and is thereby connected to the ninth wiring layer 659 in the thickness direction. The twelfth via 562 is covered with the third interlayer insulating film 413.

[0100] The tenth wiring layer 660 is formed of a metal such as aluminum. The tenth wiring layer 660 is connected to the twelfth via 562 in the thickness direction. The tenth wiring layer 660 is formed on the third interlayer insulating film 413, and is exposed to the outside of the third interlayer insulating film 413. The tenth wiring layer 660 is connected to the DAC 20. As described above, the seventh wiring layer 657 is connected to the DAC 20. Therefore, the second phase shifter 302 is electrically connected to the DAC 20.

[0101] 5, 7 and the like, first shifter portion 311 of third phase shifter 303 has third waveguide 423, fifth electrode 435, sixth electrode 436, fifth wiring 445 and sixth wiring 446.

[0102] Light incident on the third phase shifter 303, here, light incident on the second shifter portion 312 and propagated through the second shifter portion 312, propagates through the third waveguide 423. Furthermore, the third waveguide 423 is formed from the active layer of the semiconductor substrate 400, and is, for example, a silicon waveguide having a PN junction. Moreover, the third waveguide 423 is covered with the BOX 410 of the semiconductor substrate 400 and the first interlayer insulating film 411.

[0103] Specifically, the third waveguide 423 includes a fifth rib portion 455 , a sixth rib portion 456 , a fifth connecting portion 465 , a sixth connecting portion 466 , a fifth contact portion 475 and a sixth contact portion 476 .

[0104] The fifth rib portion 455 is N-shaped. Furthermore, the fifth rib portion 455 extends in one direction.

[0105] The sixth rib portion 456 is of P type. Furthermore, the sixth rib portion 456 extends in one direction. Furthermore, the sixth rib portion 456 is joined to the fifth rib portion 455 in the width direction. This forms a PN junction. Furthermore, the thickness of the sixth rib portion 456 is equal to the thickness of the fifth rib portion 455.

[0106] The fifth connection portion 465 is made of N-type ferrite having a higher impurity concentration than the fifth rib portion 455. + The fifth connecting portion 465 is connected in the width direction to the side of the fifth rib portion 455 opposite to the sixth rib portion 456. The thickness of the fifth connecting portion 465 is smaller than the thickness of the fifth rib portion 455.

[0107] The sixth connection portion 466 is a P + The sixth connecting portion 466 is connected in the width direction to the side of the sixth rib portion 456 opposite to the fifth rib portion 455. The thickness of the sixth connecting portion 466 is smaller than the thickness of the sixth rib portion 456.

[0108] The fifth contact portion 475 is an N-type semiconductor having a higher impurity concentration than the fifth connection portion 465. ++ The fifth contact portion 475 is a flat-shaped type. The fifth contact portion 475 is connected in the width direction to a side of the fifth connection portion 465 opposite to the fifth rib portion 455. The thickness of the fifth contact portion 475 is set to be equal to the thickness of the fifth connection portion 465, for example. Therefore, the thickness of the fifth contact portion 475 is set to be smaller than the thickness of the fifth rib portion 455.

[0109] The sixth contact portion 476 is a P ++ The sixth contact portion 476 is a flat-shaped type. The sixth contact portion 476 is connected in the width direction to the side of the sixth connection portion 466 opposite to the sixth rib portion 456. The thickness of the sixth contact portion 476 is set to be equal to the thickness of the sixth connection portion 466, for example. Therefore, the thickness of the sixth contact portion 476 is set to be smaller than the thickness of the sixth rib portion 456.

[0110] The fifth electrode 435 extends in one direction and also in the thickness direction. The fifth electrode 435 includes a thirteenth via hole 513, a thirteenth via 563, a seventh electrode layer 607, a fourteenth via hole 514, a fourteenth via 564, and an eighth electrode layer 608.

[0111] The thirteenth via hole 513 is connected to the fifth contact portion 475. Furthermore, the thirteenth via hole 513 is covered with the first interlayer insulating film 411.

[0112] The thirteenth via 563 is formed of a metal such as tungsten. The thirteenth via 563 is buried in the thirteenth via hole 513, and is thereby connected to the fifth contact portion 475 in the thickness direction. The thirteenth via 563 is covered with the first interlayer insulating film 411.

[0113] The seventh electrode layer 607 is formed of a metal such as aluminum. The seventh electrode layer 607 is connected to the thirteenth via 563 in the thickness direction. The seventh electrode layer 607 is covered with the second interlayer insulating film 412.

[0114] The fourteenth via hole 514 is connected to the seventh electrode layer 607. Furthermore, the fourteenth via hole 514 is covered with the second interlayer insulating film 412.

[0115] The fourteenth via 564 is formed of a metal such as tungsten. The fourteenth via 564 is embedded in the fourteenth via hole 514, and is thereby connected to the seventh electrode layer 607 in the thickness direction. The fourteenth via 564 is covered with the second interlayer insulating film 412.

[0116] The eighth electrode layer 608 is formed of a metal such as aluminum. The eighth electrode layer 608 is connected to the fourteenth via 564 in the thickness direction. The eighth electrode layer 608 is covered with the third interlayer insulating film 413.

[0117] The sixth electrode 436 extends in one direction and also in the thickness direction. The sixth electrode 436 includes a fifteenth via hole 515, a fifteenth via 565, a ninth electrode layer 609, a sixteenth via hole 516, a sixteenth via 566, and a tenth electrode layer 610.

[0118] The fifteenth via hole 515 is connected to the sixth contact portion 476. Furthermore, the fifteenth via hole 515 is covered with the first interlayer insulating film 411.

[0119] The fifteenth via 565 is formed of a metal such as tungsten. The fifteenth via 565 is embedded in the fifteenth via hole 515, and is thereby connected to the sixth contact portion 476 in the thickness direction. The fifteenth via 565 is covered with the first interlayer insulating film 411.

[0120] The ninth electrode layer 609 is formed of a metal such as aluminum. The ninth electrode layer 609 is connected to the fifteenth via 565 in the thickness direction. The ninth electrode layer 609 is covered with the second interlayer insulating film 412.

[0121] The sixteenth via hole 516 is connected to the ninth electrode layer 609. Furthermore, the sixteenth via hole 516 is covered with the second interlayer insulating film 412.

[0122] The sixteenth via 566 is formed of a metal such as tungsten. The sixteenth via 566 is embedded in the sixteenth via hole 516, and is thereby connected to the ninth electrode layer 609 in the thickness direction. The sixteenth via 566 is covered with the second interlayer insulating film 412.

[0123] The tenth electrode layer 610 is formed of a metal such as aluminum. The tenth electrode layer 610 is connected to the sixteenth via 566 in the thickness direction. The tenth electrode layer 610 is covered with the third interlayer insulating film 413.

[0124] The fifth wiring 445 includes an eleventh wiring layer 661 , a seventeenth via hole 517 , a seventeenth via 567 , and a twelfth wiring layer 662 .

[0125] The eleventh wiring layer 661 is formed of a metal such as aluminum. The eleventh wiring layer 661 is connected to a part of the eighth electrode layer 608 in the width direction, and extends in the width direction from the boundary with the eighth electrode layer 608. The eleventh wiring layer 661 is covered with the third interlayer insulating film 413.

[0126] The seventeenth via hole 517 is connected to the eleventh wiring layer 661. Furthermore, the seventeenth via hole 517 is covered with the third interlayer insulating film 413.

[0127] The seventeenth via 567 is formed of a metal such as tungsten. The seventeenth via 567 is embedded in the seventeenth via hole 517, and is thereby connected to the eleventh wiring layer 661 in the thickness direction. The seventeenth via 567 is covered with the third interlayer insulating film 413.

[0128] The twelfth wiring layer 662 is formed of a metal such as aluminum. The twelfth wiring layer 662 is connected to the seventeenth via 567 in the thickness direction. The twelfth wiring layer 662 is formed on the third interlayer insulating film 413, and is therefore exposed to the outside of the third interlayer insulating film 413. The twelfth wiring layer 662 is connected to the DAC 20 and is connected in parallel to the second wiring layer 652 of the first phase shifter 301.

[0129] The sixth wiring 446 includes a thirteenth wiring layer 663, an eighteenth via hole 518, an eighteenth via 568, and a fourteenth wiring layer 664, as shown in FIGS.

[0130] The thirteenth wiring layer 663 is formed of a metal such as aluminum. The thirteenth wiring layer 663 is connected to a part of the tenth electrode layer 610 in the width direction, and extends in the width direction from the boundary with the tenth electrode layer 610. The thirteenth wiring layer 663 is covered with the third interlayer insulating film 413.

[0131] The eighteenth via hole 518 is connected to the thirteenth wiring layer 663. Furthermore, the eighteenth via hole 518 is covered with the third interlayer insulating film 413.

[0132] The 18th via 568 is formed of a metal such as tungsten. The 18th via 568 is embedded in the 18th via hole 518, and is thereby connected to the 13th wiring layer 663 in the thickness direction. The 18th via 568 is covered with the third interlayer insulating film 413.

[0133] The fourteenth wiring layer 664 is made of a metal such as aluminum. The fourteenth wiring layer 664 is connected to the eighteenth via 568 in the thickness direction. The fourteenth wiring layer 664 is formed on the third interlayer insulating film 413, and is exposed to the outside of the third interlayer insulating film 413. The fourteenth wiring layer 664 is connected to the DAC 20 and is connected in parallel to the fourth wiring layer 654 of the first phase shifter 301. Therefore, the first voltage V1 is applied to the first shifter section 311.

[0134] 9 and other figures, the second shifter portion 312 of the third phase shifter 303 has a fourth waveguide 424, a seventh electrode 437, an eighth electrode 438, a seventh wiring 447 and an eighth wiring 448.

[0135] The light incident on the third phase shifter 303 propagates through the fourth waveguide 424. Furthermore, the fourth waveguide 424 is formed from an active layer of the semiconductor substrate 400, and is, for example, a silicon waveguide having a PN junction. Moreover, the fourth waveguide 424 is covered with the BOX 410 of the semiconductor substrate 400 and the first interlayer insulating film 411.

[0136] Specifically, the fourth waveguide 424 includes a seventh rib portion 457 , an eighth rib portion 458 , a seventh connecting portion 467 , an eighth connecting portion 468 , a seventh contact portion 477 and an eighth contact portion 478 .

[0137] The seventh rib portion 457 is N-shaped. In addition, the seventh rib portion 457 extends in one direction.

[0138] The eighth rib portion 458 is of P type. Furthermore, the eighth rib portion 458 extends in one direction. Furthermore, the eighth rib portion 458 is joined to the seventh rib portion 457 in the width direction. This forms a PN junction. Furthermore, the thickness of the eighth rib portion 458 is equal to the thickness of the seventh rib portion 457.

[0139] The seventh connection portion 467 is an N-type rib portion having a higher impurity concentration than the seventh rib portion 457. + The seventh connecting portion 467 is connected in the width direction to the side of the seventh rib portion 457 opposite to the eighth rib portion 458. The thickness of the seventh connecting portion 467 is smaller than the thickness of the seventh rib portion 457.

[0140] The eighth connection portion 468 is a P +The eighth connecting portion 468 is connected in the width direction to the eighth rib portion 458 on the opposite side to the seventh rib portion 457. The thickness of the eighth connecting portion 468 is smaller than the thickness of the eighth rib portion 458.

[0141] The seventh contact portion 477 is an N-type semiconductor having a higher impurity concentration than the seventh connection portion 467. ++ The seventh contact portion 477 is a flat-shaped type. The seventh contact portion 477 is connected in the width direction to the side of the seventh connection portion 467 opposite to the seventh rib portion 457. The thickness of the seventh contact portion 477 is set to be equal to the thickness of the seventh connection portion 467, for example. Therefore, the thickness of the seventh contact portion 477 is set to be smaller than the thickness of the seventh rib portion 457.

[0142] The eighth contact portion 478 is a P ++ The eighth contact portion 478 is a flat-shaped type. The eighth contact portion 478 is connected in the width direction to the side of the eighth connection portion 468 opposite to the eighth rib portion 458. The thickness of the eighth contact portion 478 is set to be equal to the thickness of the eighth connection portion 468, for example. Therefore, the thickness of the eighth contact portion 478 is set to be smaller than the thickness of the eighth rib portion 458.

[0143] The seventh electrode 437 extends in one direction and also in the thickness direction. The seventh electrode 437 includes a nineteenth via hole 519, a nineteenth via 569, and an eleventh electrode layer 611.

[0144] The nineteenth via hole 519 is connected to the seventh contact portion 477. Furthermore, the nineteenth via hole 519 is covered with the first interlayer insulating film 411.

[0145] The 19th via 569 is formed of a metal such as tungsten. The 19th via 569 is buried in the 19th via hole 519, and is thereby connected to the seventh contact portion 477 in the thickness direction. The 19th via 569 is covered with the first interlayer insulating film 411.

[0146] The eleventh electrode layer 611 is formed of a metal such as aluminum. The eleventh electrode layer 611 is connected to the nineteenth via 569 in the thickness direction. The eleventh electrode layer 611 is covered with the second interlayer insulating film 412.

[0147] The eighth electrode 438 extends in one direction and also in the thickness direction. The eighth electrode 438 includes a twentieth via hole 520, a twentieth via 570, and a twelfth electrode layer 612.

[0148] The twentieth via hole 520 is connected to the eighth contact portion 478. Furthermore, the twentieth via hole 520 is covered with the first interlayer insulating film 411.

[0149] The twentieth via 570 is formed of a metal such as tungsten. The twentieth via 570 is embedded in the twentieth via hole 520, and is thereby connected to the eighth contact portion 478 in the thickness direction. The twentieth via 570 is covered with the first interlayer insulating film 411.

[0150] The twelfth electrode layer 612 is formed of a metal such as aluminum. The twelfth electrode layer 612 is connected to the twentieth via 570 in the thickness direction. The twelfth electrode layer 612 is covered with the second interlayer insulating film 412.

[0151] The seventh wiring 447 includes a fifteenth wiring layer 665, a twenty-first via hole 521, a twenty-first via 571, a sixteenth wiring layer 666, a twenty-second via hole 522, a twenty-second via 572, and a seventeenth wiring layer 667, as shown in FIGS.

[0152] The fifteenth wiring layer 665 is formed of a metal such as aluminum. The fifteenth wiring layer 665 is connected to a part of the eleventh electrode layer 611 in the width direction, and extends in the width direction from the boundary with the eleventh electrode layer 611. The fifteenth wiring layer 665 is covered with the second interlayer insulating film 412.

[0153] The twenty-first via hole 521 is connected to the fifteenth wiring layer 665. Furthermore, the twenty-first via hole 521 is covered with the second interlayer insulating film 412.

[0154] The 21st via 571 is formed of a metal such as tungsten. The 21st via 571 is embedded in the 21st via hole 521, and is thereby connected to the 15th wiring layer 665 in the thickness direction. The 21st via 571 is covered with the second interlayer insulating film 412.

[0155] The sixteenth wiring layer 666 is formed of a metal such as aluminum. The sixteenth wiring layer 666 is connected to the twenty-first via 571 in the thickness direction. The sixteenth wiring layer 666 is covered with the third interlayer insulating film 413.

[0156] The twenty-second via hole 522 is connected to the sixteenth wiring layer 666. Furthermore, the twenty-second via hole 522 is covered with the third interlayer insulating film 413.

[0157] The 22-th via 572 is formed of a metal such as tungsten. The 22-th via 572 is embedded in the 22-th via hole 522, and is thereby connected to the 16th wiring layer 666 in the thickness direction. The 22-th via 572 is covered with the third interlayer insulating film 413.

[0158] The seventeenth wiring layer 667 is formed of a metal such as aluminum. The seventeenth wiring layer 667 is connected to the twenty-second via 572 in the thickness direction. The seventeenth wiring layer 667 is formed on the third interlayer insulating film 413, and is therefore exposed to the outside of the third interlayer insulating film 413. The seventeenth wiring layer 667 is connected to the DAC 20 and is connected in parallel to the seventh wiring layer 657 of the second phase shifter 302.

[0159] As shown in FIG. 14, the eighth wiring 448 includes an eighteenth wiring layer 668, a twenty-third via hole 523, a twenty-third via 573, a nineteenth wiring layer 669, a twenty-fourth via hole 524, a twenty-fourth via 574, and a twentieth wiring layer 670.

[0160] The 18th wiring layer 668 is formed of a metal such as aluminum. The 18th wiring layer 668 is connected to a part of the 12th electrode layer 612 in the width direction, and extends in the width direction from the boundary with the 12th electrode layer 612. The 18th wiring layer 668 is covered with the second interlayer insulating film 412.

[0161] The 23rd via hole 523 is connected to the 18th wiring layer 668. Furthermore, the 23rd via hole 523 is covered with the second interlayer insulating film 412.

[0162] The 23rd via 573 is formed of a metal such as tungsten. The 23rd via 573 is embedded in the 23rd via hole 523, and is thereby connected to the 18th wiring layer 668 in the thickness direction. The 23rd via 573 is covered with the second interlayer insulating film 412.

[0163] The nineteenth wiring layer 669 is formed of a metal such as aluminum. The nineteenth wiring layer 669 is connected to the twenty-third via 573 in the thickness direction. The nineteenth wiring layer 669 is covered with the third interlayer insulating film 413.

[0164] The 24th via hole 524 is connected to the 19th wiring layer 669. Furthermore, the 24th via hole 524 is covered with the third interlayer insulating film 413.

[0165] The 24th via 574 is formed of a metal such as tungsten. The 24th via 574 is embedded in the 24th via hole 524, and is thereby connected to the 19th wiring layer 669 in the thickness direction. The 24th via 574 is covered with the third interlayer insulating film 413.

[0166] The twentieth wiring layer 670 is formed of a metal such as aluminum. The twentieth wiring layer 670 is connected to the twenty-fourth via 574 in the thickness direction. The twentieth wiring layer 670 is formed on the third interlayer insulating film 413, and is exposed to the outside of the third interlayer insulating film 413. The twentieth wiring layer 670 is connected to the DAC 20 and is connected in parallel to the tenth wiring layer 660 of the second phase shifter 302. Therefore, the second voltage V2 is applied to the second shifter section 312.

[0167] 8 and 11, the insulating layer 313 of the third phase shifter 303 is formed by not doping impurities into the active layer of the semiconductor substrate 400. Therefore, the impurity concentration of the insulating layer 313 is lower than the impurity concentrations of the first waveguide 421, the second waveguide 422, the third waveguide 423, and the fourth waveguide 424. Furthermore, the insulating layer 313 is covered with the BOX 410 and the first interlayer insulating film 411.

[0168] 5, the minimum distance in the thickness direction from the third waveguide 423 to the boundary between the seventh electrode layer 607 and the eleventh wiring layer 661 is defined as a first distance T1. As shown in Fig. 9, the minimum distance in the thickness direction from the fourth waveguide 424 to the boundary between the eleventh electrode layer 611 and the fifteenth wiring layer 665 is defined as a second distance T2.

[0169] The first distance T1 and the second distance T2 are different, that is, T1 ≠ T2. Here, the first distance T1 is greater than the second distance T2, that is, T1 > T2. Note that the first distance T1 may be smaller than the second distance T2, that is, T1 <T2とされてもよい。

[0170] 5, the first distance T1 is equal to the minimum distance in the thickness direction from the first waveguide 421 to the boundary between the second electrode layer 602 and the first wiring layer 651. Furthermore, as shown in Fig. 14, the first distance T1 is equal to the minimum distance in the thickness direction from the first waveguide 421 to the boundary between the fourth electrode layer 604 and the third wiring layer 653. Moreover, as shown in Fig. 7 and Fig. 10, the first distance T1 is equal to the minimum distance in the thickness direction from the third waveguide 423 to the boundary between the tenth electrode layer 610 and the thirteenth wiring layer 663.

[0171] Further, here, as shown in FIG. 5, the second distance T2 is equal to the minimum distance in the thickness direction from the second waveguide 422 to the boundary between the fifth electrode layer 605 and the fifth wiring layer 655. Also, as shown in FIG. 14, the second distance T2 is equal to the minimum distance in the thickness direction from the second waveguide 422 to the boundary between the sixth electrode layer 606 and the eighth wiring layer 658. Furthermore, the second distance T2 is equal to the minimum distance in the thickness direction from the fourth waveguide 424 to the boundary between the twelfth electrode layer 612 and the eighteenth wiring layer 668. Therefore, the minimum distance in the thickness direction from the fourth waveguide 424 to the boundary between the twelfth electrode layer 612 and the eighteenth wiring layer 668 is different from the minimum distance in the thickness direction from the third waveguide 423 to the boundary between the tenth electrode layer 610 and the thirteenth wiring layer 663.

[0172] As described above, first phase shifter 301, second phase shifter 302, and third phase shifter 303 are configured. Next, a method for manufacturing first phase shifter 301, second phase shifter 302, and third phase shifter 303 will be described.

[0173] A semiconductor substrate 400 such as SOI is prepared. Then, an active layer of the semiconductor substrate 400 is formed into a shape corresponding to the insulating layer 313, the first waveguide 421, the second waveguide 422, the third waveguide 423, and the fourth waveguide 424 by etching. Then, the first waveguide 421, the second waveguide 422, the third waveguide 423, and the fourth waveguide 424 are formed by ion implantation or the like into the active layer having a shape corresponding to the first waveguide 421, the second waveguide 422, the third waveguide 423, and the fourth waveguide 424. At this time, ions are not implanted into the active layer having a shape corresponding to the insulating layer 313, so that the insulating layer 313 is not doped with impurities.

[0174] Next, first interlayer insulating film 411 is formed by CVD or the like. As a result, insulating layer 313, first waveguide 421, second waveguide 422, third waveguide 423, and fourth waveguide 424 are covered with first interlayer insulating film 411. Note that CVD is an abbreviation for Chemical Vapor Deposition.

[0175] Subsequently, a first via hole 501, a third via hole 503, a seventh via hole 507, and an eighth via hole 508 are formed in the first interlayer insulating film 411 by etching. Also, a thirteenth via hole 513, a fifteenth via hole 515, a nineteenth via hole 519, and a twentieth via hole 520 are formed in the first interlayer insulating film 411.

[0176] Thereafter, a first via 551, a third via 553, a seventh via 557, an eighth via 558, a thirteenth via 563, a fifteenth via 565, a nineteenth via 569, and a tenth via 570 are formed by CVD or the like.

[0177] Further, by CVD, etching, etc., a first electrode layer 601, a third electrode layer 603, a fifth electrode layer 605, a sixth electrode layer 606, a seventh electrode layer 607, a ninth electrode layer 609, an eleventh electrode layer 611, and a twelfth electrode layer 612 are formed on the first interlayer insulating film 411. Furthermore, at this time, a fifth wiring layer 655, an eighth wiring layer 658, a fifteenth wiring layer 665, and an eighteenth wiring layer 668 are formed, as shown in Figures 5, 9, 12, and 14.

[0178] Next, the second interlayer insulating film 412 is formed by CVD or the like. As a result, the first electrode layer 601, the third electrode layer 603, the fifth electrode layer 605, the sixth electrode layer 606, the seventh electrode layer 607, the ninth electrode layer 609, the eleventh electrode layer 611, and the twelfth electrode layer 612 are covered with the second interlayer insulating film 412. In addition, the fifth wiring layer 655, the eighth wiring layer 658, the fifteenth wiring layer 665, and the eighteenth wiring layer 668 are covered with the second interlayer insulating film 412.

[0179] Subsequently, a second via hole 502, a fourth via hole 504, a ninth via hole 509, an eleventh via hole 511, a fourteenth via hole 514, a sixteenth via hole 516, and a twenty-third via hole 523 are formed in the second interlayer insulating film 412 by etching.

[0180] Thereafter, the second via 552, the fourth via 554, the ninth via 559, the eleventh via 561, the fourteenth via 564, the sixteenth via 566, and the twenty-third via 573 are formed by CVD or the like.

[0181] Further, by CVD, etching, and the like, a second electrode layer 602, a fourth electrode layer 604, an eighth electrode layer 608, and a tenth electrode layer 610 are formed on the second interlayer insulating film 412. Furthermore, at this time, a first wiring layer 651, a third wiring layer 653, a sixth wiring layer 656, a ninth wiring layer 659, an eleventh wiring layer 661, a thirteenth wiring layer 663, a sixteenth wiring layer 666, and a nineteenth wiring layer 669 are formed, as shown in FIG.

[0182] Next, the third interlayer insulating film 413 is formed by CVD or the like. As a result, the second electrode layer 602, the fourth electrode layer 604, the eighth electrode layer 608, and the tenth electrode layer 610 are covered with the third interlayer insulating film 413. In addition, the first wiring layer 651, the third wiring layer 653, the sixth wiring layer 656, the ninth wiring layer 659, the eleventh wiring layer 661, the thirteenth wiring layer 663, the sixteenth wiring layer 666, and the nineteenth wiring layer 669 are covered with the third interlayer insulating film 413.

[0183] Subsequently, a fifth via hole 505, a sixth via hole 506, a tenth via hole 510, and a twelfth via hole 512 are formed in the third interlayer insulating film 413 by etching. In addition, a seventeenth via hole 517, an eighteenth via hole 518, a twenty-second via hole 522, and a twenty-fourth via hole 524 are formed.

[0184] Thereafter, a fifth via 555, a sixth via 556, a tenth via 560, a twelfth via 562, a seventeenth via 567, an eighteenth via 568, a twenty-second via 572 and a twenty-fourth via 574 are formed by CVD or the like.

[0185] Furthermore, by CVD, etching, etc., a second wiring layer 652, a fourth wiring layer 654, a seventh wiring layer 657, a tenth wiring layer 660, a twelfth wiring layer 662, a fourteenth wiring layer 664, a seventeenth wiring layer 667, and a twentieth wiring layer 670 are formed on the third interlayer insulating film 413. Thus, the first phase shifter 301, the second phase shifter 302, and the third phase shifter 303 are completed.

[0186] As described above, the first phase shifter 301, the second phase shifter 302, and the third phase shifter 303 are manufactured. In addition, the optical phased array 5 including the phase shifter array 30 of this embodiment is used for Lidar. Next, the operation of the optical phased array 5 when used for Lidar will be described with reference to FIG.

[0187] The splitter tree 10 splits incident light Li from a light source (not shown) into N light beams. Each of the split light beams is incident on a first phase shifter 301, a second phase shifter 302, and a third phase shifter 303 of the subarray 300, respectively. At this time, as shown in FIG. 15, the arrangements of the first phase shifter 301, the second phase shifter 302, and the third phase shifter 303 are adjusted so that the phases of the light beams incident on the first phase shifter 301, the second phase shifter 302, and the third phase shifter 303 are Φ0.

[0188] Here, the first phase shifter 301 at one end of the phase shifter array 30 in the parallel direction Dp is defined as the first phase shifter. The second phase shifter 302 at the other end of the phase shifter array 30 in the parallel direction Dp is defined as the Nth phase shifter. Counting from the first phase shifter 301 at one end in the parallel direction Dp to the second phase shifter 302 at the other end, the i-th first phase shifter 301, second phase shifter 302, or third phase shifter 303 is defined as the i-th phase shifter.

[0189] A first voltage V1 is applied from the DAC 20 to the first phase shifter 301, which is the first phase shifter. For example, here, the first voltage V1 is reverse biased. At this time, a depletion layer is formed in the PN junction of the first waveguide 421, so that the carrier concentration of the first waveguide 421 decreases. This increases the refractive index of the first waveguide 421. Therefore, the optical path length of the light propagating through the first phase shifter increases. Therefore, the optical path difference increases, so that the phase difference between the light incident on the first phase shifter and the light emitted from the first phase shifter increases. Furthermore, the first voltage V1 and the like are adjusted so that the phase difference between the light incident on the first phase shifter and the light emitted from the first phase shifter is ΔΦ. Therefore, the phase of the light emitted from the first phase shifter is Φ0+ΔΦ.

[0190] Also, the second voltage V2 is applied from the DAC 20 to the second phase shifter 302, which is the Nth phase shifter. For example, here, the second voltage V2 is reverse biased like the first voltage V1. At this time, a depletion layer is formed in the PN junction of the second waveguide 422, so that the carrier concentration of the second waveguide 422 decreases. This increases the refractive index of the second waveguide 422. Therefore, the optical path length of the light propagating through the Nth phase shifter increases. Therefore, the optical path difference increases, so that the phase difference between the light incident on the Nth phase shifter and the light emitted from the Nth phase shifter increases. Furthermore, the second voltage V2 and the like are adjusted so that the phase difference between the light incident on the Nth phase shifter and the light emitted from the Nth phase shifter is N×ΔΦ. Therefore, the phase of the light emitted from the Nth phase shifter is Φ0+N×ΔΦ.

[0191] Moreover, if the i-th phase shifter is the first phase shifter 301, the first voltage V1 is applied to the i-th phase shifter from the DAC 20. At this time, similar to the case of the first phase shifter, the phase difference between the light incident on the i-th phase shifter and the light emitted from the i-th phase shifter becomes large. Furthermore, the first voltage V1, etc. are adjusted so that the phase difference between the light incident on the i-th phase shifter and the light emitted from the i-th phase shifter becomes i×ΔΦ. Therefore, if the i-th phase shifter is the first phase shifter 301, the phase of the light emitted from the i-th phase shifter is Φ0+i×ΔΦ.

[0192] Moreover, if the i-th phase shifter is the second phase shifter 302, the second voltage V2 is applied to the i-th phase shifter from the DAC 20. At this time, similar to the case of the N-th phase shifter, the phase difference between the light incident on the i-th phase shifter and the light emitted from the i-th phase shifter becomes large. Furthermore, the second voltage V2 etc. are adjusted so that the phase difference between the light incident on the i-th phase shifter and the light emitted from the i-th phase shifter becomes i×ΔΦ. Therefore, if the i-th phase shifter is the second phase shifter 302, the phase of the light emitted from the i-th phase shifter is Φ0+i×ΔΦ.

[0193] Also, if the i-th phase shifter is the third phase shifter 303, a first voltage V1 is applied to the first shifter section 311 of the i-th phase shifter. At this time, a depletion layer is formed in the PN junction of the third waveguide 423, so that the carrier concentration of the third waveguide 423 decreases. This increases the refractive index of the third waveguide 423. Therefore, the optical path length of the light propagating through the i-th phase shifter becomes large. Also, a second voltage V2 is applied to the second shifter section 312 of the i-th phase shifter. At this time, a depletion layer is formed in the PN junction of the fourth waveguide 424, so that the carrier concentration of the fourth waveguide 424 decreases. This increases the refractive index of the fourth waveguide 424. Therefore, the optical path length of the light propagating through the i-th phase shifter becomes large. Therefore, the optical path difference becomes large, so that the phase difference between the light incident on the i-th phase shifter and the light emitted from the i-th phase shifter becomes large. Furthermore, the first voltage V1, the second voltage V2, the length of the first shifter section 311, the length of the second shifter section 312, etc. are adjusted so that the phase difference between the light incident on the i-th phase shifter and the light emitted from the i-th phase shifter is i×ΔΦ. Therefore, if the i-th phase shifter is the third phase shifter 303, the phase of the light emitted from the i-th phase shifter is Φ0+i×ΔΦ.

[0194] Then, the light emitted from the 1st to Nth phase shifters is incident on the corresponding antenna 700. The antenna array 70 emits light at an angle according to the phase of the light changed by the phase shifter array 30, i.e., the phase of the light changed by the 1st to Nth phase shifters. Specifically, the antenna array 70 emits light at an angle according to Φ0, . . . , Φ0+i×ΔΦ, . . . , Φ0+N×ΔΦ.

[0195] Here, the first phase shifter 301, the second phase shifter 302, and the third phase shifter 303 are arranged at equal intervals in the parallel direction Dp, and the distance between adjacent phase shifters in the parallel direction Dp is d. Furthermore, the direction perpendicular to the direction in which the phase shifters extend, from the first phase shifter to the Nth phase shifter, is defined as the positive direction of the X-axis. Furthermore, the direction perpendicular to the X-axis, from the phase shifter array 30 to the antenna array 70, is defined as the positive direction of the Z-axis. Furthermore, the direction perpendicular to the X-axis and the Z-axis is defined as the positive direction of the Y-axis. Note that the X-axis, Y-axis, and Z-axis are expressed in the right-handed system.

[0196] In this case, the emission angle ψ, which is the angle of the light emitted from the antenna array 70 as shown in Fig. 16, is expressed by the following relational expression (7). Note that here, the emission angle ψ is an angle around the Z axis. In addition, in the following relational expression (7), λ is the wavelength of the light emitted from the antenna array 70, and corresponds to the wavelength of the light from a light source (not shown). Furthermore, π is the circular constant.

[0197]

number

[0198] In addition, at this time, the radiation angle Δψ of the light emitted from the antenna array 70 shown in Fig. 16 is expressed by the following relational expression (8). Therefore, the radiation angle Δψ increases as N increases. Note that here, the radiation angle Δψ is an angle range around the Z axis.

[0199]

number

[0200] Furthermore, the light emitted from the antenna array 70 is reflected by an object (not shown). The light reflected by the object is incident on the antenna array 70. The reflected light incident on the antenna array 70 passes through the phase shifter array 30 and the splitter tree 10 and is incident on an optical receiver (not shown). Furthermore, a measuring device (not shown) measures the distance from the optical phased array 5 to the object and the shape of the object using information on the incident light Li from the light source and the reflected light incident on the optical receiver.

[0201] As described above, the optical phased array 5 is used for Lidar. Next, it will be described how the optical phased array 5 including the phase shifter array 30 of this embodiment prevents the DAC 20, which corresponds to the control unit, from becoming large.

[0202] Here, Patent Document 1 describes a subarray in which 16 phase shifters are grouped. The number of subarrays is four. In this case, the total number of phase shifters is 64. Furthermore, since a voltage signal for changing the phase of light incident on the phase shifter is output from the control unit to each of the 16 phase shifters in the subarray, the number of control signals is 16. In this case, when the number of phase shifters in the subarray increases, the number of voltage signals from the control unit increases accordingly, and the number of wirings of the control unit increases. Therefore, the control unit becomes larger.

[0203] In contrast, in the optical phased array 5 including the phase shifter array 30 of the present embodiment, the subarray 300 includes a first phase shifter 301, a second phase shifter 302, and a third phase shifter 303. The first phase shifter 301 changes the phase of light incident on the first phase shifter 301 by applying a first voltage V1 from the DAC 20. The second phase shifter 302 changes the phase of light incident on the second phase shifter 302 by applying a second voltage V2 from the DAC 20. The third phase shifter 303 includes a first shifter section 311 and a second shifter section 312. The first voltage V1 is applied to the first shifter section 311. The second voltage V2 is applied to the second shifter section 312. Moreover, the third phase shifter 303 changes the phase of the light incident on the third phase shifter 303 by applying a first voltage V1 to the first shifter portion 311 and a second voltage V2 to the second shifter portion 312.

[0204] As a result, the number of voltages output from DAC 20 to one subarray 300 becomes two. Therefore, the number of voltages from DAC 20 is obtained by dividing twice N, which corresponds to the total number of phase shifters, by a value obtained by adding 2 to S, which corresponds to the number of third phase shifters 303 in one subarray 300, i.e., 2×N / (S+2). Therefore, even if the number of phase shifters increases, the number of third phase shifters 303 in one subarray 300 increases, so that an increase in the number of voltages from DAC 20 is suppressed.

[0205] For example, assume that N, which corresponds to the total number of phase shifters, is 64. Also assume that S, which corresponds to the number of third phase shifters 303 in one subarray 300, is 14. In this case, the number of phase shifters in one subarray 300 is 16, which is the sum of the number of first phase shifters 301 and the number of second phase shifters 302 and 14. At this time, the number of voltages from the DAC 20 is 2×64 / 16, which is 8. Therefore, in the optical phased array 5 including the phase shifter array 30 of this embodiment, the number of control signals is reduced compared to the optical phased array described in Patent Document 1. Therefore, an increase in the number of wirings, etc. of the DAC 20 is suppressed, and therefore an increase in the size of the DAC 20 is suppressed.

[0206] In addition, since the size of the DAC 20 is suppressed, it is possible to increase N, which corresponds to the total number of phase shifters, by the amount of the suppression of the size of the DAC 20. When N increases, the radiation angle Δψ decreases as shown in the above relational expression (8). Therefore, the spatial resolution of the optical phased array 5 can be improved.

[0207] In addition, the optical phased array 5 including the phase shifter array 30 of the first embodiment also provides the following effects.

[0208] [1-1] A plurality of third phase shifters 303 are arranged in the parallel direction Dp. The length of the first shifter portion 311 decreases in sequence from the third phase shifter 303 adjacent to the first phase shifter 301 to the third phase shifter 303 adjacent to the second phase shifter 302. That is, La(1)>La(2)>La(3)>...>La(S-2)>La(S-1)>La(S). Furthermore, the length of the second shifter portion 312 increases in sequence from the third phase shifter 303 adjacent to the first phase shifter 301 to the third phase shifter 303 adjacent to the second phase shifter 302. That is, Lb(1) <Lb(2)<Lb(3)<···<Lb(S-2)<Lb(S-1)<Lb(S)とされている。

[0209] As a result, the optical path length of light incident on the first shifter portion 311 becomes shorter in sequence from the third phase shifter 303 adjacent to the first phase shifter 301 toward the third phase shifter 303 adjacent to the second phase shifter 302. Also, the optical path length of light incident on the second shifter portion 312 becomes longer in sequence from the third phase shifter 303 adjacent to the first phase shifter 301 toward the third phase shifter 303 adjacent to the second phase shifter 302. As a result, it becomes easier to adjust the optical path length of the light incident on the third phase shifter 303, and therefore it becomes easier to adjust the phase difference between the light incident on the third phase shifter 303 and the light emitted from the third phase shifter 303. Therefore, starting from the first phase shifter, the phase differences of the phase shifter array 30 tend to be ΔΦ, 2×ΔΦ, . . ., i×ΔΦ, . . ., N×ΔΦ, and tend to have a linear relationship. Therefore, the accuracy of ΔΦ is improved, and the accuracy of the exit angle ψ is improved.

[0210] [1-2] The length of the first phase shifter 301, the length of the second phase shifter 302, and the sum of the lengths of the corresponding first shifter section 311 and second shifter section 312 are equal to each other. That is, La(0)=Lb(0)=La(S)+Lb(S)=Ls.

[0211] This makes the optical path lengths equal when the first voltage V1 and the second voltage V2 are not applied. This suppresses the phase difference between the phase shifters caused by the difference in optical path length when the first voltage V1 and the second voltage V2 are not applied. This makes it easier for the phase differences of the phase shifter array 30 to be ΔΦ, 2×ΔΦ, . . ., i×ΔΦ, . . ., N×ΔΦ, and easier to have a linear relationship. This improves the accuracy of ΔΦ, and therefore the accuracy of the exit angle ψ.

[0212] [1-3] The first shifter portion 311 is formed so that the above-mentioned relational expression (1) is satisfied, and the second shifter portion 312 is formed so that the above-mentioned relational expression (2) is satisfied.

[0213] As a result, the optical path length of light incident on the first shifter section 311 is shortened in order from the third phase shifter 303 adjacent to the first phase shifter 301 to the third phase shifter 303 adjacent to the second phase shifter 302. Also, the optical path length of light incident on the second shifter section 312 is lengthened in order from the third phase shifter 303 adjacent to the first phase shifter 301 to the third phase shifter 303 adjacent to the second phase shifter 302. As a result, similarly to the above, each phase difference of the phase shifter array 30 is easily made to be ΔΦ, 2×ΔΦ, . . ., i×ΔΦ, . . ., N×ΔΦ, and is easily made to have a linear relationship. Therefore, the accuracy of ΔΦ is improved, and therefore the accuracy of the exit angle ψ is improved.

[0214] [1-4] The third phase shifter 303 includes an insulating layer 313. The insulating layer 313 has electrical insulation properties and provides insulation between the first shifter portion 311 and the second shifter portion 312. The impurity concentration of the insulating layer 313 is lower than the impurity concentrations of the first waveguide 421, the second waveguide 422, the third waveguide 423, and the fourth waveguide 424.

[0215] As a result, when first waveguide 421, second waveguide 422, third waveguide 423, and fourth waveguide 424 are formed by ion implantation or the like, impurities are not doped by not implanting ions, and thus insulating layer 313 can be formed. This eliminates the need to add a separate process for forming insulating layer 313. This makes it easier to form insulating layer 313.

[0216] [1-5] The first distance T1 and the second distance T2 are different. This makes it easier for the fifth wiring 445 and the seventh wiring 447 to have a twisted positional relationship. This prevents the fifth wiring 445 and the seventh wiring 447 from being electrically connected to each other.

[0217] In addition, the distance in the thickness direction from the third waveguide 423 to the boundary between the tenth electrode layer 610 and the thirteenth wiring layer 663 is different from the distance in the thickness direction from the fourth waveguide 424 to the boundary between the twelfth electrode layer 612 and the eighteenth wiring layer 668. This makes it easier for the sixth wiring 446 and the eighth wiring 448 to be in a twisted positional relationship. This prevents the sixth wiring 446 and the eighth wiring 448 from being electrically connected to each other.

[0218] [1-6] The phase shifter array 30 has a plurality of subarrays 300.

[0219] As a result, when N corresponding to the total number of phase shifters is fixed, if the number of subarrays 300 increases, the number of phase shifters in one subarray 300 decreases. Also, if the number of phase shifters in one subarray 300 decreases, the size of one subarray 300 decreases. Therefore, the manufacturing variation in one subarray 300 becomes smaller than when the size of one subarray 300 is relatively large. Therefore, the variation in Φ0 corresponding to the phase of light incident on the first phase shifter 301, the second phase shifter 302, and the third phase shifter 303 and i×ΔΦ corresponding to each phase difference becomes smaller. Therefore, the variation in the exit angle ψ becomes smaller.

[0220] Second embodiment In the second embodiment, the optical phased array 5 includes a first grating coupler 71, a second grating coupler 72, and a phase difference monitor circuit 80, as shown in FIG. 17. The DAC 20 further includes a storage medium. Furthermore, the processing of the DAC 20 differs from that of the first embodiment. Other than these, the second embodiment is similar to the first embodiment.

[0221] The first grating coupler 71 is an element that inputs and outputs light to and from the first phase shifter 301. The second grating coupler 72 is an element that inputs and outputs light to and from the second phase shifter 302. The phase difference monitor circuit 80 has, for example, a Macha-Chernobach interferometer that converts the phase difference of light into an intensity difference of light. The phase difference monitor circuit 80 is connected to the first grating coupler 71 and the second grating coupler 72. A first table indicating the relationship between the first voltage V1 and the phase difference between the light incident on the first phase shifter 301 and the light emitted from the first phase shifter 301 is stored in the storage medium of the DAC 20. A second table indicating the relationship between the second voltage V2 and the phase difference between the light incident on the second phase shifter 302 and the light emitted from the second phase shifter 302 is stored in the storage medium of the DAC 20.

[0222] Here, the phase difference between the light incident on the first phase shifter 301 and the light emitted from the first phase shifter 301 is detected by using the first grating coupler 71 and the phase difference monitor circuit 80. Furthermore, the DAC 20 generates a first table by using the phase difference obtained by the first grating coupler 71 and the phase difference monitor circuit 80 and the first voltage V1. Furthermore, the phase difference between the light incident on the second phase shifter 302 and the light emitted from the second phase shifter 302 is detected by using the second grating coupler 72 and the phase difference monitor circuit 80. Furthermore, the DAC 20 generates a second table by using the phase difference obtained by the second grating coupler 72 and the phase difference monitor circuit 80 and the second voltage V2.

[0223] Then, the generated first table and second table are stored in the storage medium of the DAC 20. Furthermore, the DAC 20 calculates the first voltage V1 and the second voltage V2 using the stored first table and second table and the desired phase difference. Furthermore, the DAC 20 applies the calculated first voltage V1 to the first phase shifter 301 and the first shifter unit 311. Furthermore, the DAC 20 applies the calculated second voltage V2 to the second phase shifter 302 and the second shifter unit 312.

[0224] The optical phased array 5 of the second embodiment is configured as described above. The second embodiment also provides the same effects as the first embodiment. The second embodiment also provides the following effects.

[0225] [2] The DAC 20 calculates a first voltage V1 using the first table and the desired phase difference, and calculates a second voltage V2 using the second table and the desired phase difference.

[0226] This makes it easier for the phase differences of the phase shifter array 30 to be ΔΦ, 2×ΔΦ, . . ., i×ΔΦ, . . ., N×ΔΦ, and to have a linear relationship. Therefore, the accuracy of ΔΦ is improved, and therefore the accuracy of the exit angle ψ is improved.

[0227] Third embodiment In the third embodiment, the optical phased array 5 further includes a phase difference monitor circuit 80 as shown in Fig. 18. Also, the processing of the DAC 20 is different from that of the first embodiment. Other than this, it is similar to the first embodiment.

[0228] The phase difference monitor circuit 80 has a Machachender interferometer that converts the phase difference of light into the intensity difference of light. The phase difference monitor circuit 80 is connected to the first phase shifter 301 and the second phase shifter 302 via an antenna 700. The phase difference monitor circuit 80 detects the phase difference between the light incident on the first phase shifter 301 and the light emitted from the first phase shifter 301. The phase difference monitor circuit 80 detects the phase difference between the light incident on the second phase shifter 302 and the light emitted from the second phase shifter 302. The phase difference monitor circuit 80 outputs a signal corresponding to the detected phase difference to the DAC 20. The phase difference monitor circuit 80 is connected to the first phase shifter 301 and the second phase shifter 302 via the antenna 700, but is not limited thereto. The phase difference monitor circuit 80 may be connected to the first phase shifter 301 and the second phase shifter 302 via a waveguide instead of the antenna 700. In this case, the phase difference monitor circuit 80 detects the phase difference caused by the first phase shifter 301 and the second phase shifter 302 via the waveguide.

[0229] Moreover, the DAC20 controls the first voltage V1 based on the phase difference between the light incident on the first phase shifter 301 and the light emitted from the first phase shifter 301 acquired from the phase difference monitor circuit 80. For example, when the phase difference between the light incident on the first phase shifter 301 and the light emitted from the first phase shifter 301 is larger than a desired phase difference, the DAC20 reduces the first voltage V1. This increases the carrier concentration of the first waveguide 421 and the third waveguide 423. Therefore, the refractive index of the first waveguide 421 and the third waveguide 423 decreases. Therefore, the optical path length of the light propagating through the first phase shifter 301 and the first shifter section 311 decreases. Therefore, the DAC20 reduces each phase difference of the phase shifter array 30 to a desired phase difference.

[0230] Furthermore, the DAC20 controls the second voltage V2 based on the phase difference between the light incident on the second phase shifter 302 and the light emitted from the second phase shifter 302 acquired from the phase difference monitor circuit 80. For example, when the phase difference between the light incident on the second phase shifter 302 and the light emitted from the second phase shifter 302 is larger than a desired phase difference, the DAC20 reduces the second voltage V2. This increases the carrier concentration of the second waveguide 422 and the fourth waveguide 424. Therefore, the refractive index of the second waveguide 422 and the fourth waveguide 424 decreases. Therefore, the optical path length of the light propagating through the second phase shifter 302 and the second shifter section 312 decreases. Therefore, the DAC20 reduces each phase difference of the phase shifter array 30 to a desired phase difference.

[0231] The optical phased array 5 of the third embodiment is configured as described above. The third embodiment also provides the same effects as the first embodiment. The third embodiment also provides the following effects.

[0232] [3] DAC20 controls a first voltage V1 based on the phase difference between light incident on first phase shifter 301 and light emitted from first phase shifter 301. Also, DAC20 controls a second voltage V2 based on the phase difference between light incident on second phase shifter 302 and light emitted from second phase shifter 302.

[0233] This makes it easier for the phase differences of the phase shifter array 30 to be ΔΦ, 2×ΔΦ, . . ., i×ΔΦ, . . ., N×ΔΦ, and to have a linear relationship. Therefore, the accuracy of ΔΦ is improved, and therefore the accuracy of the exit angle ψ is improved.

[0234] (Other embodiments) The present disclosure is not limited to the above-described embodiments, and appropriate modifications can be made to the above-described embodiments. Furthermore, in each of the above-described embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where they are particularly clearly stated as essential or where they are clearly considered essential in principle.

[0235] The control unit and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method described in the present disclosure may be realized by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be realized by one or more special-purpose computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by a computer.

[0236] In each of the above embodiments, the light from the splitter tree 10 enters the second shifter section 312, and the light propagating through the second shifter section 312 enters the first shifter section 311. In addition, the light from the first shifter section 311 enters the antenna 700. In contrast to this, the light from the splitter tree 10 may enter the first shifter section 311, and the light propagating through the first shifter section 311 may enter the second shifter section 312. At this time, the light from the second shifter section 312 enters the antenna 700.

[0237] In each of the above embodiments, the first voltage V1 and the second voltage V2 are reverse biased, but the present invention is not limited to this. The first voltage V1 and the second voltage V2 may be forward biased.

[0238] In each of the above embodiments, the number of third phase shifters 303 in one subarray 300 is two or more. In contrast, the number of third phase shifters 303 in one subarray 300 may be one. [Explanation of symbols]

[0239] 10. Splitter Tree 20 DAC 30 Phase Shifter Array 70 Antenna Array 300 Subarray 301 1st Phase Shifter 302 Second Phase Shifter 303 3rd Phase Shifter 311 First Shifter Section 312 Second shifter section

Claims

1. 1. A phase shifter array comprising: at least one subarray (300) having a first phase shifter (301), a second phase shifter (302) aligned with the first phase shifter, and at least one third phase shifter (303) aligned with the first phase shifter and the second phase shifter between the first phase shifter and the second phase shifter, The first phase shifter changes a phase of light incident on the first phase shifter by applying a first voltage (V1) from a control unit (20) that applies a voltage to the subarray; the second phase shifter changes a phase of light incident on the second phase shifter by application of a second voltage (V2) from the control unit; The third phase shifter is a first shifter unit (311) to which the first voltage is applied; a second shifter unit (312) to which the second voltage is applied; Including, The third phase shifter is a phase shifter array that changes the phase of light incident on the third phase shifter by applying the first voltage to the first shifter section and the second voltage to the second shifter section.

2. a plurality of the third phase shifters are arranged in a parallel direction (Dp) of the first phase shifters and the second phase shifters; a length of the first phase shifter portion decreases in order from the third phase shifter adjacent to the first phase shifter toward the third phase shifter adjacent to the second phase shifter, 2 . The phase shifter array according to claim 1 , wherein the lengths of the second shifter portions increase in order from the third phase shifter adjacent to the first phase shifter to the third phase shifter adjacent to the second phase shifter.

3. 2. The phase shifter array according to claim 1, wherein a length of the first phase shifter, a length of the second phase shifter, and a sum of lengths of the first shifter portions and the second shifter portions corresponding to each other are equal to each other.

4. a length from the first phase shifter to the second phase shifter in a parallel direction (Dp) of the first phase shifter and the second phase shifter is defined as Ws, a distance from the first phase shifter to the third phase shifter in the parallel direction is defined as D(S); The length of the first shifter portion is La(S), If the length of the second shifter portion is Lb(S), then The first shifter section includes: [0010] The above formula (1) is satisfied. The second shifter section [0025] 2. The phase shifter array according to claim 1, which is formed so that the following relational expression (2) holds:

5. The first phase shifter has a first waveguide (421); The second phase shifter has a second waveguide (422); The first shifter section includes a third waveguide (423); the second shifter section includes a fourth waveguide (424); Light incident on the first phase shifter propagates through the first waveguide, the light incident on the second phase shifter propagates through the second waveguide; light incident on the third phase shifter propagates through the third waveguide and the fourth waveguide; the first waveguide, the second waveguide, the third waveguide, and the fourth waveguide each include a PN junction; the third phase shifter has an electrical insulating property and includes an insulating portion (313) that provides insulation between the first shifter portion and the second shifter portion; 2. The phase shifter array according to claim 1, wherein the insulating portion has an impurity concentration lower than impurity concentrations of the first waveguide, the second waveguide, the third waveguide and the fourth waveguide.

6. The phase shifter array further comprises a semiconductor substrate (400); The first phase shifter has a first waveguide (421); The second phase shifter has a second waveguide (422); the first shifter section includes a third waveguide (423), a first electrode (435, 436), and a first wiring (445, 446); the second shifter section includes a fourth waveguide (424), a second electrode (437, 438), and a second wiring (447, 448); Light incident on the first phase shifter propagates through the first waveguide, the light incident on the second phase shifter propagates through the second waveguide; light incident on the third phase shifter propagates through the third waveguide and the fourth waveguide; the first electrode is connected to the third waveguide and extends in a thickness direction of the semiconductor substrate, the first wiring is connected to the first electrode and the control unit, the second electrode is connected to the fourth waveguide and extends in the thickness direction, the second wiring is connected to the second electrode and the control unit, The first wiring includes a first wiring layer (661, 663) connected to the first electrode in a direction intersecting the thickness direction, The second wiring includes a second wiring layer (665, 668) connected to the second electrode in a direction intersecting the thickness direction, 3. The phase shifter array according to claim 1, wherein a distance (T1) from the third waveguide to a boundary between the first electrode and the first wiring layer in the thickness direction is different from a distance (T2) from the fourth waveguide to a boundary between the second electrode and the second wiring layer in the thickness direction.

7. 3. The phase shifter array according to claim 1, wherein the phase shifter array includes a plurality of the subarrays.

8. 1. An optical phased array, comprising: A splitter tree (10) that splits an incident light (Li) into multiple lights; A control unit (20) that applies a voltage; a phase shifter array (30) that changes the phase of light from the splitter tree by applying a voltage from the control unit; an antenna array (70) that emits light at an angle according to the phase of the light changed by the phase shifter array; Equipped with The phase shifter array includes: at least one subarray (300) including a first phase shifter (301), a second phase shifter (302) aligned with the first phase shifter, and at least one third phase shifter (303) aligned with the first phase shifter and the second phase shifter between the first phase shifter and the second phase shifter, the first phase shifter changes a phase of light incident on the first phase shifter by applying a first voltage (V1) from the control unit; the second phase shifter changes a phase of light incident on the second phase shifter by application of a second voltage (V2) from the control unit; The third phase shifter is a first shifter unit (311) to which the first voltage is applied; a second shifter unit (312) to which the second voltage is applied; Including, The third phase shifter changes a phase of light incident on the third phase shifter by applying the first voltage to the first shifter section and the second voltage to the second shifter section.

9. The control unit is controlling the first voltage based on a phase difference between light incident on the first phase shifter and light emitted from the first phase shifter; The optical phased array according to claim 8 , wherein the second voltage is controlled based on a phase difference between light incident on the second phase shifter and light emitted from the second phase shifter.

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