Optical circuit

Abstract

Provided is an optical circuit with which versatility as well as user convenience can be improved. This optical circuit comprises: an optical switch circuit that includes N × N Mach–Zehnder interferometers arranged in a matrix of N rows and N columns, where N is an integer 8 or greater; a first switching unit that switches an external connection destination of each of M Mach–Zehnder interferometers, where M is any integer from 1 to N, among the N Mach–Zehnder interferometers included in the first column of the matrix formed by the N × N Mach–Zehnder interferometers; and a second switching unit that switches an external connection destination of each of L Mach–Zehnder interferometers, where L is any integer from 1 to N, among the N Mach–Zehnder interferometers included in the Nth column of the matrix.

Description

optical circuit

[0001] The present invention relates to an optical circuit. This application claims priority to Japanese Patent Application No. 2023-123531, filed on July 28, 2023, the contents of which are incorporated herein by reference.

[0002] 2. Description of the Related Art In recent years, research and development has been conducted on optical circuits that perform processing using optical signals.

[0003] In this regard, optical switch circuits are known that efficiently switch optical signals required for optical communications, optical interconnects, etc. without photoelectric conversion, using the optical signals as they are (see Non-Patent Documents 1 and 2).

[0004] Furthermore, Clements-type optical circuits and Bell-type optical circuits are known as unitary matrix operation circuits that efficiently perform matrix operations required for deep learning and the like using optical signals (see Non-Patent Documents 3 and 4).

[0005] Keijiro Suzuki, et al., "Ultra-compact 8 × 8 strictly-non-blocking Si-wire PILOSS switch," OPTICS EXPRESS, Vol. 22, Issue 4, 24 February 2014, pp. 3887-3894.Ken Tanizawa, et al., "Ultra-compact 32 × 32 strictly-non-blocking Si-wire optical switch with fan-out LGA interposer," OPTICS EXPRESS, Vol. 23, Issue 13, 29 June 2015, pp. 17599-17606.William R. Clements, et al., "Optimal design for universal multiport interferometers," Optica, Vol. 3, Issue 12, 6 December 2016, pp. 1460-1465.BA Bell, and IA Walmsley., "Further compactifying linear optical unitaries," APL Photonics, Vol. 6, Issue 7, 13 July 2021, 070804.

[0006] Optical circuits such as optical switch circuits and unitary matrix operation circuits are often used for a single purpose, and therefore, when a user of the optical circuit wants to change the purpose of the optical circuit, they often have to change the destinations to which it is connected, which can be time-consuming and laborious.

[0007] The present disclosure has been made in consideration of the above circumstances, and an object of the present disclosure is to provide an optical circuit that is versatile and can improve user convenience.

[0008] According to an aspect of the present disclosure, an optical circuit includes an optical switch circuit including N×N Mach-Zehnder interferometers arranged in a matrix of N rows and N columns, where N is an integer greater than or equal to 8; a first switching unit that switches external connection destinations of M Mach-Zehnder interferometers out of the N Mach-Zehnder interferometers included in a first column of the matrix formed by the N×N Mach-Zehnder interferometers, where M is an integer greater than or equal to 1 and less than or equal to N; and a second switching unit that switches external connection destinations of L Mach-Zehnder interferometers out of the N Mach-Zehnder interferometers included in the Nth column of the matrix, where L is an integer greater than or equal to 1 and less than or equal to N.

[0009] According to the present disclosure, it is possible to improve versatility and user convenience.

[0010] 7 is a diagram showing an example of the configuration of the optical circuit 1. FIG. 7 is a diagram showing an example of the optical circuit 1 operating as a PILOSS optical switch circuit that outputs eight first optical signals in response to eight input of first optical signals. FIG. 7 is a diagram showing another example of the optical circuit 1 operating as a PILOSS optical switch circuit that outputs eight first optical signals in response to eight input of first optical signals. FIG. 7 is a diagram showing an example of 32 first Mach-Zehnder interferometers operating as a first unitary matrix operation circuit. FIG. 7 is a diagram showing an example of 32 second Mach-Zehnder interferometers operating as a second unitary matrix operation circuit. FIG. 7 is a diagram showing an example of an MZI matrix in which a cross waveguide CS is connected to a third port and a fourth port of each Mach-Zehnder interferometer. FIG. 7 is a diagram showing another example of the configuration of the optical circuit 1. FIG. 7 is a diagram showing an example of the optical circuit 1 shown in FIG. 7 operating as a unitary matrix operation circuit that performs a first unitary matrix operation. FIG. 7 is a diagram showing an example of the optical circuit 1 shown in FIG. 7 operating as a unitary matrix operation circuit that performs a second unitary matrix operation. FIG. 10 is a diagram showing yet another example of the configuration of the optical circuit 1.

[0011] Embodiments Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0012] <Outline of Optical Circuit> First, an outline of the optical circuit according to the embodiment will be described.

[0013] The optical circuit according to the embodiment includes an optical switch circuit including N×N Mach-Zehnder interferometers arranged in a matrix of N rows and N columns, where N is an integer greater than or equal to 8; a first switching unit that switches the external connection destination of each of M Mach-Zehnder interferometers out of the N Mach-Zehnder interferometers included in the first column of the matrix formed by the N×N Mach-Zehnder interferometers, where M is an integer greater than or equal to 1 and less than or equal to N; and a second switching unit that switches the external connection destination of each of L Mach-Zehnder interferometers out of the N Mach-Zehnder interferometers included in the Nth column of the matrix, where L is an integer greater than or equal to 1 and less than or equal to N.

[0014] As a result, the optical circuit according to the embodiment allows a user to change the connection destination using the first switching unit and the second switching unit, thereby easily changing the application of the optical circuit. As a result, the optical circuit can improve versatility and user convenience. The application can be expressed, for example, by the type of optical signal to be processed by the optical circuit, the operation of the optical circuit performed on the optical signal, etc.

[0015] The configuration of the optical circuit according to the embodiment will be described in detail below.

[0016] <Configuration of Optical Circuit> The configuration of an optical circuit according to an embodiment will be described below using the optical circuit 1 as an example. Note that in this embodiment, the connection between various components means the connection via a waveguide through which an optical signal is propagated. For example, in this embodiment, when it is said that two Mach-Zehnder interferometers are connected to each other, it means that these two Mach-Zehnder interferometers are connected via a waveguide. Furthermore, in this embodiment, when it is said that a Mach-Zehnder interferometer and a certain amplitude modulator are connected, it means that the Mach-Zehnder interferometer and the amplitude modulator are connected via a waveguide.

[0017] FIG. 1 is a diagram showing an example of the configuration of an optical circuit 1. As shown in FIG.

[0018] The optical circuit 1 is an optical circuit that can switch its operation depending on the application. For example, the optical circuit 1 can selectively switch between two operations: an operation for switching optical signals required for optical communication, optical interconnection, etc., and an operation for performing unitary matrix operations using optical signals, in accordance with control from a control device communicatively connected to the optical circuit 1.

[0019] Here, the control device is an information processing device that controls the optical circuit 1. The control device may be any device that is capable of controlling the optical circuit 1, and may be, for example, an information processing device dedicated to controlling the optical circuit 1, a workstation, a desktop PC (Personal Computer), a notebook PC, etc., but is not limited to these. The control device may also be a processor such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array). For this reason, in this embodiment, an illustrated description of the control device will be omitted.

[0020] The optical circuit 1 includes an optical switch circuit 10, a first switching unit 11, and a second switching unit 12. Note that the optical circuit 1 may include other circuits, other members, other devices, etc. in addition to these.

[0021] The optical switch circuit 10 is a switch circuit including N×N Mach-Zehnder interferometers arranged in a matrix of N rows and N columns. The following description will be given, as an example, of a case where the optical switch circuit 10 is a PILOSS (Path Independent Insertion Loss) optical switch circuit. Note that the optical switch circuit 10 may be any other type of optical switch circuit other than a PILOSS optical switch circuit, as long as it includes N×N Mach-Zehnder interferometers arranged in a matrix of N rows and N columns. Here, N is an integer equal to or greater than 8. The following description will be given, as an example, of a case where N is 8. In this embodiment, the Mach-Zehnder interferometer is a known interferometer, and therefore a detailed description thereof will be omitted.

[0022] In this example, the optical switch circuit 10 includes 8 × 8 Mach-Zehnder interferometers (i.e., 64 Mach-Zehnder interferometers) arranged in a matrix of 8 rows and 8 columns, as shown in Figure 1. Note that, hereinafter, for convenience of explanation, the matrix formed by the 8 × 8 Mach-Zehnder interferometers included in the optical switch circuit 10 will be simply referred to as an MZI (Mach-Zehnder Interferometer) matrix. Also, hereinafter, for convenience of explanation, of the two directions parallel to each row of the MZI matrix, the direction from the Nth column of the MZI matrix to the first column of the MZI matrix will be referred to as the first row direction, and of the two directions, the direction from the first column of the MZI matrix to the Nth column of the MZI matrix will be referred to as the second row direction. When there is no need to distinguish between the two directions, the two directions will be collectively referred to as the row direction. Furthermore, for convenience of explanation, of the two directions parallel to each column of the matrix, the direction from the Nth row of the MZI matrix to the first row of the MZI matrix will be referred to as the first column direction, and of the two directions, the direction from the first row of the MZI matrix to the Nth row of the MZI matrix will be referred to as the second column direction. When it is not necessary to distinguish between the two directions, the two directions will be collectively referred to as the column direction. The arrows shown in Figure 1 indicate the first row direction, second row direction, first column direction, and second column direction in Figure 1. Furthermore, for convenience of explanation, of the four ports possessed by each of all Mach-Zehnder interferometers appearing in this embodiment (i.e., four ports provided in all of the Mach-Zehnder interferometers and capable of inputting and outputting optical signals), the port on the first row direction side and the first column direction side will be referred to as the first port, and of the four ports, the port on the first row direction side and the second column direction side will be referred to as the second port. Furthermore, in the following, for convenience of explanation, the port of the four ports that is on the second row direction side and the first column direction side will be referred to as the third port, and the port of the four ports that is on the second row direction side and the second column direction side will be referred to as the fourth port. In addition, in the following, for convenience of explanation, the eight rows included in the MZI matrix will be referred to as the first row, second row, third row, fourth row, fifth row, sixth row, seventh row, and eighth row in order from the first column direction side toward the second column direction.Also, for the sake of convenience, in the following description, the eight columns included in the MZI matrix will be referred to as the first column, second column, third column, fourth column, fifth column, sixth column, seventh column, and eighth column in order from the first row direction toward the second row direction.

[0023] Hereinafter, for convenience of explanation, the eight Mach-Zehnder interferometers included in the i-th row of the MZI matrix will be referred to as Mach-Zehnder interferometer Mi1, Mach-Zehnder interferometer Mi2, Mach-Zehnder interferometer Mi3, Mach-Zehnder interferometer Mi4, Mach-Zehnder interferometer Mi5, Mach-Zehnder interferometer Mi6, Mach-Zehnder interferometer Mi7, and Mach-Zehnder interferometer Mi8 in order from the first row direction to the second row direction, as shown in FIG. That is, for example, the eight Mach-Zehnder interferometers included in the first row of the MZI matrix are, in order from the first row direction toward the second row direction, Mach-Zehnder interferometer M11, Mach-Zehnder interferometer M12, Mach-Zehnder interferometer M13, Mach-Zehnder interferometer M14, Mach-Zehnder interferometer M15, Mach-Zehnder interferometer M16, Mach-Zehnder interferometer M17, and Mach-Zehnder interferometer M18. Furthermore, for example, the eight Mach-Zehnder interferometers included in the fifth row of the MZI matrix are, in order from the first row direction toward the second row direction, Mach-Zehnder interferometer M51, Mach-Zehnder interferometer M52, Mach-Zehnder interferometer M53, Mach-Zehnder interferometer M54, Mach-Zehnder interferometer M55, Mach-Zehnder interferometer M56, Mach-Zehnder interferometer M57, and Mach-Zehnder interferometer M58.

[0024] When i is any of 1 to 8, the first and second ports of the Mach-Zehnder interferometer Mi1 are connected to a first switching unit 11. When i is any of 1 to 8, the third and fourth ports of the Mach-Zehnder interferometer Mi8 are connected to a second switching unit 12.

[0025] Furthermore, when j is any value from 2 to 8, the first port of the Mach-Zehnder interferometer M1j is connected to the third port of the Mach-Zehnder interferometer M1j-1 via a waveguide. For example, the first port of the Mach-Zehnder interferometer M12 is connected to the third port of the Mach-Zehnder interferometer M11 via a waveguide.

[0026] Furthermore, when j is any one of 1 to 7, the third port of the Mach-Zehnder interferometer M1j is connected to the first port of the Mach-Zehnder interferometer M1j+1 via a waveguide. For example, the third port of the Mach-Zehnder interferometer M17 is connected to the first port of the Mach-Zehnder interferometer M18 via a waveguide.

[0027] Furthermore, when j is any value from 2 to 8, the second port of the Mach-Zehnder interferometer M8j is connected to the fourth port of the Mach-Zehnder interferometer M8j-1 via a waveguide. For example, the second port of the Mach-Zehnder interferometer M82 is connected to the fourth port of the Mach-Zehnder interferometer M81 via a waveguide.

[0028] Furthermore, when j is any one of 1 to 7, the fourth port of the Mach-Zehnder interferometer M8j is connected to the second port of the Mach-Zehnder interferometer M8j+1 via a waveguide. For example, the fourth port of the Mach-Zehnder interferometer M87 is connected to the second port of the Mach-Zehnder interferometer M88 via a waveguide.

[0029] Furthermore, when i is any value from 2 to 8 and j is any value from 2 to 8, the first port of the Mach-Zehnder interferometer Mij is connected to the fourth port of the Mach-Zehnder interferometer Mi-1j-1 via a waveguide. For example, the first port of the Mach-Zehnder interferometer M22 is connected to the fourth port of the Mach-Zehnder interferometer M11 via a waveguide.

[0030] Furthermore, when i is any one of 1 to 7 and j is any one of 2 to 8, the second port of the Mach-Zehnder interferometer Mij is connected to the third port of the Mach-Zehnder interferometer Mi+1j-1 via a waveguide. For example, the second port of the Mach-Zehnder interferometer M72 is connected to the third port of the Mach-Zehnder interferometer M81 via a waveguide.

[0031] Furthermore, when i is any value from 2 to 8 and j is any value from 1 to 7, the third port of the Mach-Zehnder interferometer Mij is connected to the second port of the Mach-Zehnder interferometer Mi-1j+1 via a waveguide. For example, the third port of the Mach-Zehnder interferometer M27 is connected to the second port of the Mach-Zehnder interferometer M18 via a waveguide.

[0032] Furthermore, when i is any value from 1 to 7 and j is any value from 1 to 7, the fourth port of the Mach-Zehnder interferometer Mij is connected to the first port of the Mach-Zehnder interferometer Mi+1j+1 via a waveguide. For example, the fourth port of the Mach-Zehnder interferometer M77 is connected to the first port of the Mach-Zehnder interferometer M88 via a waveguide.

[0033] That is, as described above, the optical switch circuit 10 is a PILOSS optical switch circuit. Since the PILOSS optical switch circuit is a known circuit, further detailed description of the connection between two adjacent Mach-Zehnder interferometers in the 8×8 Mach-Zehnder interferometers of the optical switch circuit 10 will be omitted. Also, in FIG. 1 , to avoid cluttering the diagram, the waveguides parallel to the row direction are depicted as having a different waveguide length from the waveguides intersecting the row direction. In practice, the waveguides connecting two adjacent Mach-Zehnder interferometers in the 8×8 Mach-Zehnder interferometers may all have the same waveguide length, except for differences due to manufacturing errors. Also, the waveguides connecting two adjacent Mach-Zehnder interferometers in the 8×8 Mach-Zehnder interferometers may have different waveguide lengths. The waveguides parallel to the row direction may actually have the same waveguide length as the waveguides intersecting the row direction, except for differences due to manufacturing errors. Alternatively, a crossing waveguide structure used when two waveguides intersecting the row direction intersect each other may be inserted into the waveguides parallel to the row direction, so that the waveguides parallel to the row direction and the waveguides intersecting the row direction have the same insertion loss, except for differences due to manufacturing errors. Alternatively, a crossing waveguide structure need not be inserted into the waveguides parallel to the row direction.

[0034] The first switching unit 11 switches the external connection destinations of each of M Mach-Zehnder interferometers among the eight Mach-Zehnder interferometers included in the first column of the MZI matrix. M may be any integer between 1 and N (i.e., in this example, an integer between 1 and 8). In the example shown in FIG. 1 , M is 8. In this case, the first switching unit 11 switches the external connection destinations of each of the eight Mach-Zehnder interferometers. For example, the first switching unit 11 switches the connection destinations based on a control signal including information indicating the use of the optical switch circuit 10. Note that the first switching unit 11 may be configured to switch the connection destinations based on a control signal including other information, or may be configured to switch the connection destinations by another method.

[0035] The first switching unit 11 includes, for example, one or more Mach-Zehnder interferometers that switch the connection destinations of some or all of the first ports of each of the M Mach-Zehnder interferometers and the second ports of each of the M Mach-Zehnder interferometers. The one or more Mach-Zehnder interferometers are Mach-Zehnder interferometers that are not included in the MZI matrix. In the example shown in FIG. 1 , the first switching unit 11 includes 16 Mach-Zehnder interferometers that switch the connection destinations of all of the first ports of each of the M Mach-Zehnder interferometers and the second ports of each of the M Mach-Zehnder interferometers. For ease of explanation, the 16 Mach-Zehnder interferometers will be referred to in the following description as first connection destination switching Mach-Zehnder interferometer A1, first connection destination switching Mach-Zehnder interferometer A2, ..., first connection destination switching Mach-Zehnder interferometer A16, in that order from the first row direction toward the second row direction. Furthermore, for ease of explanation, the 16 Mach-Zehnder interferometers will be collectively referred to as first connection destination switching Mach-Zehnder interferometer A unless it is necessary to distinguish between them.

[0036] Here, in the example shown in FIG. 1 , when i is any of 1 to 8, the first port of the Mach-Zehnder interferometer located at row i, column 1 of the MZI matrix is ​​connected to the third port of the first connection destination switching Mach-Zehnder interferometer A. Also, in this example, in this case, the second port of the Mach-Zehnder interferometer located at row i, column 1 of the MZI matrix is ​​connected to the third port of the first connection destination switching Mach-Zehnder interferometer A. For example, the first port of the Mach-Zehnder interferometer M11 is connected to the third port of the first connection destination switching Mach-Zehnder interferometer A1. Also, for example, the second port of the Mach-Zehnder interferometer M11 is connected to the third port of the first connection destination switching Mach-Zehnder interferometer A2. Also, for example, the first port of the Mach-Zehnder interferometer M51 is connected to the third port of the first connection destination switching Mach-Zehnder interferometer A9. Furthermore, for example, the second port of the Mach-Zehnder interferometer M51 is connected to the third port of the first connection destination switching Mach-Zehnder interferometer A10. As a result, each Mach-Zehnder interferometer included in the first column of the MZI matrix can input and output optical signals to and from the first connection destination switching Mach-Zehnder interferometer A connected to, for example, either the first port or the second port or both.

[0037] Here, a first port of the first connection destination switching Mach-Zehnder interferometer A is connected to a first connection destination. Also, a second port of the first connection destination switching Mach-Zehnder interferometer A is connected to a second connection destination different from the first connection destination. Therefore, the first connection destination switching Mach-Zehnder interferometer A can switch the destination for inputting or outputting an optical signal between the first connection destination and the second connection destination in response to a control signal from the aforementioned control device.

[0038] In addition, instead of a configuration including one or more Mach-Zehnder interferometers that switch the connection destinations of some or all of the first ports of each of the M Mach-Zehnder interferometers and the second ports of each of the M Mach-Zehnder interferometers, the first switching unit 11 may be another configuration that is capable of switching the connection destinations.

[0039] The second switching unit 12 switches the external connection destinations of each of L Mach-Zehnder interferometers out of the eight Mach-Zehnder interferometers included in the Nth column of the MZI matrix. L may be any integer between 1 and N (i.e., in this example, an integer between 1 and 8). In the example shown in FIG. 1 , L is 8. In this case, the second switching unit 12 switches the external connection destinations of each of the eight Mach-Zehnder interferometers. For example, the second switching unit 12 switches the connection destinations based on the above-mentioned control signal. Note that the second switching unit 12 may be configured to switch the connection destinations based on a control signal including other information, or may be configured to switch the connection destinations by another method.

[0040] The second switching unit 12 includes, for example, one or more Mach-Zehnder interferometers that switch the connection destinations of some or all of the third ports of each of the L Mach-Zehnder interferometers and the fourth ports of each of the L Mach-Zehnder interferometers. The one or more Mach-Zehnder interferometers are Mach-Zehnder interferometers that are not included in the MZI matrix. In the example shown in FIG. 1 , the second switching unit 12 includes 16 Mach-Zehnder interferometers that switch the connection destinations of all of the third ports of each of the L Mach-Zehnder interferometers and the fourth ports of each of the L Mach-Zehnder interferometers. For ease of explanation, the 16 Mach-Zehnder interferometers will be referred to in the following description as second connection destination switching Mach-Zehnder interferometer B1, second connection destination switching Mach-Zehnder interferometer B2, ..., second connection destination switching Mach-Zehnder interferometer B16, in that order from the first row direction toward the second row direction. Furthermore, for ease of explanation, the 16 Mach-Zehnder interferometers will be collectively referred to as second connection destination switching Mach-Zehnder interferometer B unless it is necessary to distinguish between them.

[0041] Here, in the example shown in FIG. 1 , when i is any of 1 to 8, the third port of the Mach-Zehnder interferometer located in row i, column N of the MZI matrix is ​​connected to the first port of the second connection destination switching Mach-Zehnder interferometer B. Also, in this example, in this case, the fourth port of the Mach-Zehnder interferometer located in row i, column N of the MZI matrix is ​​connected to the first port of the second connection destination switching Mach-Zehnder interferometer B. For example, the third port of the Mach-Zehnder interferometer M18 is connected to the first port of the second connection destination switching Mach-Zehnder interferometer B1. Also, for example, the fourth port of the Mach-Zehnder interferometer M18 is connected to the first port of the second connection destination switching Mach-Zehnder interferometer B2. Also, for example, the third port of the Mach-Zehnder interferometer M58 is connected to the first port of the second connection destination switching Mach-Zehnder interferometer B9. Furthermore, for example, the fourth port of the Mach-Zehnder interferometer M58 is connected to the first port of the second connection destination switching Mach-Zehnder interferometer B10. As a result, each Mach-Zehnder interferometer included in the Nth column of the MZI matrix can input and output optical signals to and from the second connection destination switching Mach-Zehnder interferometer B connected to, for example, either the third port or the fourth port or both.

[0042] Here, the third port of the second connection destination switching Mach-Zehnder interferometer B is connected to the third connection destination. Also, the fourth port of the second connection destination switching Mach-Zehnder interferometer B is connected to a fourth connection destination different from the third connection destination. Therefore, the second connection destination switching Mach-Zehnder interferometer B can switch the destination for inputting or outputting an optical signal between the third connection destination and the fourth connection destination in response to a control signal from the aforementioned control device.

[0043] In addition, the second switching unit 12 may be configured in another way that is capable of switching the connection destinations, instead of being configured to include one or more Mach-Zehnder interferometers that switch the connection destinations of some or all of the third ports of each of the L Mach-Zehnder interferometers and the fourth ports of each of the L Mach-Zehnder interferometers.

[0044] Here, the first and second connection destinations are signal sources of optical signals when the third and fourth connection destinations are output destinations of optical signals. In this case, the type of optical signal input from the first connection destination to the optical switch circuit 10 is different from the type of optical signal input from the second connection destination to the optical switch circuit 10. Furthermore, the first and second connection destinations are output destinations of optical signals when the third and fourth connection destinations are signal sources of optical signals. That is, the optical switch circuit 10 can selectively or simultaneously perform both an operation of receiving an optical signal from the first row direction side and outputting the optical signal to the second row direction side, and an operation of receiving an optical signal from the second row direction side and outputting the optical signal to the first row direction side. Hereinafter, for convenience of explanation, the optical signals input / output between the first and third connection destinations and the optical switch circuit 10, as shown in FIG. 1, will be referred to as first optical signals. In the following description, for convenience of explanation, the optical signals input / output between the second and fourth connection destinations and the optical switch circuit 10 as shown in FIG. 1 will be referred to as second optical signals.

[0045] Furthermore, by including the first switching unit 11 and the second switching unit 12, the optical circuit 1 can, for example, switch at least one of a plurality of optical signals input to the optical switch circuit 10 to a different type of optical signal by the first switching unit 11 or the second switching unit 12. Furthermore, by including the first switching unit 11 and the second switching unit 12, the optical circuit 1 can, for example, output at least one of a plurality of optical signals output from the optical switch circuit 10 to a different output destination by the first switching unit 11 or the second switching unit 12. As a result, the optical circuit 1 can be easily used for a plurality of applications, improving versatility and user convenience.

[0046] Each of the first and second connection destinations may be an on-chip signal source or an on-chip optical receiver. Each of the third and fourth connection destinations may be an on-chip signal source or an on-chip optical receiver. When each of the first to fourth connection destinations is on-chip, the optical circuit 1 can stably perform the unitary matrix operation described below. This is because, for example, when an optical signal is input or output to or from the optical circuit 1 using an optical fiber or the like, it is known that calculation errors occur due to phase fluctuations that occur during propagation through the optical fiber.

[0047] Furthermore, the optical circuit 1 may be configured to include various devices (e.g., a phase modulator, an optical branching device, an optical power monitor, etc.) provided at desired positions among the positions at which the optical signal propagates within the optical circuit 1. For example, the optical circuit 1 may be provided with phase modulators at the first and second ports of the Mach-Zehnder interferometer in the first row of the optical switch circuit 10. This is because, in the operation of the optical circuit 1 as an optical switch and as a unitary matrix operation circuit, improvement in the controllability of the circuit and reduction in circuit operation errors can be expected.

[0048] As described above, the optical circuit 1 configured as above can switch its operation depending on the application. Therefore, the following describes each operation that the optical circuit 1 can switch.

[0049] <Operation Example 1 of Optical Circuit> The optical circuit 1 can operate, for example, as a single PILOSS optical switch circuit. More specifically, the optical circuit 1 can operate as a PILOSS optical switch circuit that receives eight first optical signals and outputs eight first optical signals. In this case, the optical circuit 1 is used, for example, to switch optical signals required for optical communications, optical interconnects, etc.

[0050] 2 is a diagram illustrating an example of the optical circuit 1 operating as a PILOSS optical switch circuit that receives eight first optical signals and outputs eight first optical signals. In the example illustrated in FIG. 2 , the first connection destination switching Mach-Zehnder interferometer A is connected to the first connection destination. In this example, each of the first connection destination switching Mach-Zehnder interferometers A1, A4, A5, A8, A9, A12, A13, and A16 is operated by a control device as the first connection destination switching Mach-Zehnder interferometer A that inputs optical signals to the optical switch circuit 10. In FIG. 2 , the first connection destination switching Mach-Zehnder interferometers A2, A3, A6, A7, A10, A11, A14, and A15 are omitted to clearly illustrate that each of the first connection destination switching Mach-Zehnder interferometers A1, A4, A5, A8, A9, A12, A13, and A16 is operating. In this case, four first optical signals are input to the optical switch circuit 10 from the first ports of the Mach-Zehnder interferometer M11, Mach-Zehnder interferometer M31, Mach-Zehnder interferometer M51, and Mach-Zehnder interferometer M71, and four first optical signals are input to the optical switch circuit 10 from the second ports of the Mach-Zehnder interferometer M21, Mach-Zehnder interferometer M41, Mach-Zehnder interferometer M61, and Mach-Zehnder interferometer M81, respectively. In this example, the optical switch circuit 10 outputs the first optical signal from the fourth port of each of the Mach-Zehnder interferometers M18, M38, M58, and M78, and outputs the first optical signal from the third port of each of the Mach-Zehnder interferometers M28, M48, M68, and M88. Therefore, in this example, each of the second connection destination switching Mach-Zehnder interferometers B2, B3, B6, B7, B10, B11, B14, and B15 is operated by the control device as the second connection destination switching Mach-Zehnder interferometer B that outputs an optical signal from the optical switch circuit 10.2 , in order to clearly show that each of the second connection destination switching Mach-Zehnder interferometers B2, B3, B6, B7, B10, B11, B14, and B15 is operating, the second connection destination switching Mach-Zehnder interferometers B1, B4, B5, B8, B9, B12, B13, and B16 are omitted. In this example, each of the second connection destination switching Mach-Zehnder interferometers B2, B3, B6, B7, B10, B11, B14, and B15 outputs the first optical signal output from the optical switch circuit 10 to a third connection destination.

[0051] 2 to the second optical signal supplied from the second connection destination. This is because the first connection destination switching Mach-Zehnder interferometer A of the first switching unit 11 switches the connection destination from the first connection destination to the second connection destination in response to a control signal from the control device, thereby allowing the second optical signal to be input to the optical switch circuit 10. As a result, the optical circuit 1 can easily change the combination of eight optical signals input to the optical switch circuit 10 operating as a PILOSS optical switch circuit to a combination desired by the user, thereby improving versatility and user convenience.

[0052] 2 from the third connection destination to the fourth connection destination. This is because the second connection destination switching Mach-Zehnder interferometer B of the second switching unit 12 switches the connection destination from the third connection destination to the fourth connection destination in response to a control signal from the control device, thereby enabling the first optical signal to be output from the optical switch circuit 10 to the fourth connection destination. This also enables the optical circuit 1 to easily realize switching of an optical signal to output the optical signal to a destination desired by the user, thereby improving versatility and user convenience.

[0053] 2 may be reversed. That is, the optical circuit 1 may be configured to receive an optical signal via the second switching unit 12 and output an optical signal via the first switching unit 11.

[0054] 3 is a diagram showing another example of the optical circuit 1 operating as a PILOSS optical switch circuit that receives eight first optical signals and outputs eight first optical signals. In this example, the first connection destination switching Mach-Zehnder interferometer A is connected to the first connection destination. Also, in this example, the first connection destination switching Mach-Zehnder interferometers A2, A3, A6, A7, A10, A11, A14, and A15 are each operated by a control device as the first connection destination switching Mach-Zehnder interferometer A that inputs optical signals to the optical switch circuit 10. In FIG. 3 , the first connection destination switching Mach-Zehnder interferometers A1, A4, A5, A8, A9, A12, A13, and A16 are omitted to clearly show that the first connection destination switching Mach-Zehnder interferometers A2, A3, A6, A7, A10, A11, A14, and A15 are each operating. In this case, four first optical signals are input to the optical switch circuit 10 from the second ports of the Mach-Zehnder interferometer M11, Mach-Zehnder interferometer M31, Mach-Zehnder interferometer M51, and Mach-Zehnder interferometer M71, and four first optical signals are input to the first ports of the Mach-Zehnder interferometer M21, Mach-Zehnder interferometer M41, Mach-Zehnder interferometer M61, and Mach-Zehnder interferometer M81, respectively. In this example, the optical switch circuit 10 outputs the first optical signal from the third port of each of the Mach-Zehnder interferometers M18, M38, M58, and M78, and outputs the first optical signal from the fourth port of each of the Mach-Zehnder interferometers M28, M48, M68, and M88. Therefore, in this example, each of the second connection destination switching Mach-Zehnder interferometers B1, B4, B5, B8, B9, B12, B13, and B16 is operated by the control device as the second connection destination switching Mach-Zehnder interferometer B that outputs an optical signal from the optical switch circuit 10.2 , in order to clearly show that each of the second connection destination switching Mach-Zehnder interferometers B1, B4, B5, B8, B9, B12, B13, and B16 is operating, the second connection destination switching Mach-Zehnder interferometers B2, B3, B6, B7, B10, B11, B14, and B15 are omitted. In this example, each of the second connection destination switching Mach-Zehnder interferometers B1, B4, B5, B8, B9, B12, B13, and B16 outputs the first optical signal output from the optical switch circuit 10 to a third connection destination.

[0055] 3 to the second optical signal supplied from the second connection destination. This is because the first connection destination switching Mach-Zehnder interferometer A of the first switching unit 11 switches the connection destination from the first connection destination to the second connection destination in response to a control signal from the control device, thereby allowing the second optical signal to be input to the optical switch circuit 10. This allows the optical circuit 1 to easily change the combination of eight optical signals input to the optical switch circuit 10, which operates as a PILOSS optical switch circuit, to a combination desired by the user, thereby improving versatility and user convenience.

[0056] 3 from the third connection destination to the fourth connection destination. This is because the second connection destination switching Mach-Zehnder interferometer B of the first switching unit 11 switches the connection destination from the third connection destination to the fourth connection destination in response to a control signal from the control device, thereby enabling the optical switch circuit 10 to output the first optical signal to the fourth connection destination. This also enables the optical circuit 1 to easily realize switching of an optical signal to output the optical signal to a destination desired by the user, thereby improving versatility and user convenience.

[0057] The optical circuit 1 may perform the switching of the optical signal shown in Fig. 2 and the switching of the optical signal shown in Fig. 3 in parallel. This is because the operation of the optical switch circuit 10 for switching the optical signal shown in Fig. 2 results in the operation of the optical switch circuit 10 for switching the optical signal shown in Fig. 3. This is also because the operation of the optical switch circuit 10 for switching the optical signal shown in Fig. 3 results in the operation of the optical switch circuit 10 for switching the optical signal shown in Fig. 2.

[0058] Furthermore, switching of the operation of all Mach-Zehnder interferometers appearing in this embodiment (e.g., switching of the connection destination by the first connection-switching Mach-Zehnder interferometer A included in the first switching unit 11) is realized, for example, by changing the optical intensity branching ratio of the Mach-Zehnder interferometer, but is not limited to this.

[0059] <Operation Example 2 of Optical Circuit> The optical circuit 1 can operate, for example, as two or more unitary matrix operation circuits. More specifically, the optical circuit 1 can operate, for example, as two unitary matrix operation circuits that receive seven first optical signals and output seven optical signals indicating the results after performing unitary matrix operation based on the seven input first optical signals. In this case, the optical circuit 1 is used, for example, for unitary matrix operation.

[0060] The optical circuit 1 can operate the optical switch circuit 10 as two or more unitary matrix operation circuits using a new control method as described below. For simplicity of explanation, the following description will be given, as an example, of a case in which the optical circuit 1 can operate the optical switch circuit 10 as two unitary matrix operation circuits, a first unitary matrix operation circuit and a second unitary matrix operation circuit. Here, the second unitary matrix operation circuit is a unitary matrix operation circuit that does not include a Mach-Zehnder interferometer included in the first unitary matrix operation circuit. In other words, the second unitary matrix operation circuit is a unitary matrix operation circuit that is different from the first unitary matrix operation circuit. For convenience of explanation, each of the multiple Mach-Zehnder interferometers operating as the first unitary matrix operation circuit among the 8 × 8 Mach-Zehnder interferometers will be referred to as a first Mach-Zehnder interferometer. Furthermore, for convenience of explanation, in the following description, among the 8×8 Mach-Zehnder interferometers, each of the plurality of Mach-Zehnder interferometers that operate as a second unitary matrix calculation circuit will be referred to as a second Mach-Zehnder interferometer.

[0061] For example, based on a control signal from the control device, the optical circuit 1 operates 32 of the 8 × 8 Mach-Zehnder interferometers included in the MZI matrix as first Mach-Zehnder interferometers, and operates the other 32 of the 8 × 8 Mach-Zehnder interferometers as second Mach-Zehnder interferometers.

[0062] FIG. 4 is a diagram showing an example of 32 first Mach-Zehnder interferometers operating as a first unitary matrix calculation circuit. In FIG. 4 , 32 second Mach-Zehnder interferometers are omitted to clearly show the arrangement of the 32 first Mach-Zehnder interferometers. In the example shown in FIG. 4 , the first connection destination switching Mach-Zehnder interferometer A is connected to a second connection destination. In this case, the second connection destination is a signal source of an optical signal for unitary matrix calculation. In this example, each of the first connection destination switching Mach-Zehnder interferometers A3, A4, A7, A8, A11, A12, and A15 is operated by a control device as the first connection destination switching Mach-Zehnder interferometer A that inputs an optical signal to the optical switch circuit 10. 4, in order to clearly show that each of the first connection destination switching Mach-Zehnder interferometers A3, A4, A7, A8, A11, A12, and A15 is operating, the first connection destination switching Mach-Zehnder interferometers A1, A2, A5, A6, A9, A10, A13, A14, and A16 are omitted. In this case, the optical switch circuit 10 receives four second optical signals from the first ports of the Mach-Zehnder interferometers M21, M41, M61, and M81, respectively, and receives three second optical signals from the second ports of the Mach-Zehnder interferometers M21, M41, and M61, respectively. In this example, the optical switch circuit 10 outputs the second optical signal after the unitary matrix operation from the fourth port of each of the Mach-Zehnder interferometers M18, M38, M58, and M78, and outputs the second optical signal after the unitary matrix operation from the third port of each of the Mach-Zehnder interferometers M38, M58, and M78. Therefore, in this example, each of the second connection destination switching Mach-Zehnder interferometers B2, B5, B6, B9, B10, B13, and B14 is operated by the control device as the second connection destination switching Mach-Zehnder interferometer B that outputs an optical signal from the optical switch circuit 10.4 , in order to clearly show that each of the second connection destination switching Mach-Zehnder interferometers B2, B5, B6, B9, B10, B13, and B14 is operating, the second connection destination switching Mach-Zehnder interferometers B1, B3, B4, B7, B8, B11, B12, B15, and B16 are omitted. In this example, each of the second connection destination switching Mach-Zehnder interferometers B2, B5, B6, B9, B10, B13, and B14 outputs the second optical signal after the unitary matrix operation output from the optical switch circuit 10 to a fourth connection destination. In this case, the fourth connection destination is a circuit or the like that performs processing using the second optical signal after the unitary matrix operation output from the optical switch circuit 10 (e.g., a circuit that performs further optical operation, an optical switch circuit, a circuit that converts an optical signal into an electrical signal for information processing, another information processing device, etc.), but is not limited thereto.

[0063] 4, the first Mach-Zehnder interferometers and the second Mach-Zehnder interferometers included in the MZI matrix are positioned alternately in both the row and column directions of the MZI matrix. More specifically, in the example shown in FIG. 4, the first Mach-Zehnder interferometers and the second Mach-Zehnder interferometers are positioned alternately in all of the first to eighth rows. Furthermore, in this example, the first Mach-Zehnder interferometers and the second Mach-Zehnder interferometers are positioned alternately in all of the first to eighth columns. When the first Mach-Zehnder interferometer is operated as a first unitary matrix operation circuit in this manner, the first unitary matrix operation circuit operates as a unitary matrix operation circuit that receives seven optical signals as inputs and outputs seven optical signals, as shown in FIG. However, in the example shown in FIG. 4 , each of the hatched Mach-Zehnder interferometers M12, M14, M16, M18, M38, M58, M78, M81, M83, M85, and M87 is a first Mach-Zehnder interferometer operated as a phase modulator. Here, operating as a phase modulator means that the Mach-Zehnder interferometer is in a Bar state. An optical signal input to the first port is modulated in phase and then output from the third port. An optical signal input to the second port is modulated in phase and then output from the fourth port. That is, the optical intensity branching ratio of each of the hatched Mach-Zehnder interferometers M12, M14, M16, M18, M38, M58, M78, M81, M83, M85, and M87 in FIG. 4 is 100:0 (Bar:Cross). On the other hand, the optical intensity branching ratios of the Mach-Zehnder interferometers M21, M23, M25, M27, M32, M34, M36, M41, M43, M45, M47, M52, M54, M56, M61, M63, M65, M67, M72, M74, and M76 that are not hatched in Fig. 4 are set to desired ratios according to desired unitary matrix operations. Furthermore, of the Mach-Zehnder interferometers hatched in Fig. 4, the Mach-Zehnder interferometers M18, M38, M58, and M78 may be in a cross state. An optical signal input to the first port is phase-modulated and then output from the fourth port.The optical signal input to the second port is output from the third port after its phase is modulated. That is, in this case, the optical intensity branching ratio in each of the Mach-Zehnder interferometers M18, M38, M58, and M78 is 0:100 (Bar:Cross). As a result, the arrangement of the first Mach-Zehnder interferometers shown in FIG. 4 is an arrangement whose topology as an optical circuit is the same as that of a Bell-type optical circuit. That is, the 32 first Mach-Zehnder interferometers shown in FIG. 4 operate as a first unitary matrix calculation circuit.

[0064] Here, instead of a unitary matrix calculation circuit that performs unitary matrix calculation with seven optical signals as inputs and seven optical signals as outputs, the first unitary matrix calculation circuit may be operated as a unitary matrix calculation circuit that receives six or fewer optical signals as inputs and outputs the six or fewer optical signals. In this case, the arrangement of the Mach-Zehnder interferometer operating as the first Mach-Zehnder interferometer among the 8 × 8 Mach-Zehnder interferometers in the MZI matrix is ​​different from the arrangement shown in FIG. 4 . The arrangement of the first Mach-Zehnder interferometer in the MZI matrix can be determined, for example, so that the topology of the optical circuit is the same as that of a Bell-type optical circuit. The same applies to the arrangement of the second Mach-Zehnder interferometer. In other words, the optical switch circuit 10 can be operated as two unitary matrix calculation circuits by determining the arrangements of the first and second Mach-Zehnder interferometers so that the topology of the optical circuit is the same as that of a Bell-type optical circuit. Furthermore, the optical switch circuit 10 can operate as a unitary matrix operation circuit of three or more by finding an arrangement in the MZI matrix where the optical circuit 1 has the same topology as the Bell-type optical circuit. Note that the arrangement of the first Mach-Zehnder interferometer in the MZI matrix may be determined by other methods.

[0065] 4 to the first optical signal supplied from the first connection destination. This is because the first connection destination switching Mach-Zehnder interferometer A of the first switching unit 11 can input the first optical signal to the optical switch circuit 10 by switching the connection destination from the second connection destination to the first connection destination in response to a control signal from the control device. This allows the optical circuit 1 to easily change the combination of seven optical signals input to the optical switch circuit 10, which operates as a first unitary matrix operation circuit, to a combination desired by the user, thereby improving versatility and user convenience.

[0066] 4 from the fourth connection destination to the third connection destination. This is because the second connection destination switching Mach-Zehnder interferometer B of the second switching unit 12 switches the connection destination from the fourth connection destination to the third connection destination in response to a control signal from the control device, thereby enabling the second optical signal after the unitary matrix operation to be output from the optical switch circuit 10 to the third connection destination. This allows the optical circuit 1 to easily output each of the optical signals after the first unitary matrix operation to a destination desired by the user, thereby improving versatility and user convenience.

[0067] 4 may be reversed. That is, the optical circuit 1 may be configured to receive an optical signal via the second switching unit 12 and output an optical signal after a unitary matrix operation via the first switching unit 11.

[0068] On the other hand, FIG. 5 is a diagram showing an example of 32 second Mach-Zehnder interferometers operating as a second unitary matrix calculation circuit. In FIG. 5, the 32 first Mach-Zehnder interferometers are omitted to clearly show the arrangement of the 32 second Mach-Zehnder interferometers. In the example shown in FIG. 5, the first connection destination switching Mach-Zehnder interferometer A is connected to a second connection destination. In this case, the second connection destination is a signal source of an optical signal for the unitary matrix calculation. In this example, each of the first connection destination switching Mach-Zehnder interferometers A2, A5, A6, A9, A10, A13, and A14 is operated by a control device as the first connection destination switching Mach-Zehnder interferometer A that inputs an optical signal to the optical switch circuit 10. 5 , in order to clearly show that each of the first connection destination switching Mach-Zehnder interferometers A2, A5, A6, A9, A10, A13, and A14 is operating, the first connection destination switching Mach-Zehnder interferometers A1, A3, A4, A7, A8, A11, A12, A15, and A16 are omitted. In this case, the optical switch circuit 10 receives four second optical signals from the second ports of the Mach-Zehnder interferometers M11, M31, M51, and M71, respectively, and receives three second optical signals from the first ports of the Mach-Zehnder interferometers M31, M51, and M71, respectively. In this example, the optical switch circuit 10 outputs the second optical signal after the unitary matrix operation from the third port of each of the Mach-Zehnder interferometers M28, Mach-Zehnder interferometer M48, Mach-Zehnder interferometer M68, and M88, and outputs the second optical signal after the unitary matrix operation from the fourth port of each of the Mach-Zehnder interferometers M28, Mach-Zehnder interferometer M48, and M68. For this reason, in this example, each of the second connection destination switching Mach-Zehnder interferometers B3, B4, B7, B8, B11, B12, and B15 is operated by the control device as the second connection destination switching Mach-Zehnder interferometer B that outputs an optical signal from the optical switch circuit 10.5 , in order to clearly show that each of the second connection destination switching Mach-Zehnder interferometers B3, B4, B7, B8, B11, B12, and B15 is operating, the second connection destination switching Mach-Zehnder interferometers B1, B2, B5, B6, B9, B10, B13, B14, and B16 are omitted. In this example, each of the second connection destination switching Mach-Zehnder interferometers B3, B4, B7, B8, B11, B12, and B15 outputs the second optical signal after the unitary matrix operation output from the optical switch circuit 10 to a fourth connection destination. In this case, the fourth connection destination is a circuit or the like that performs processing using the second optical signal after the unitary matrix operation output from the optical switch circuit 10 (for example, a circuit that performs further optical operation, an optical switch circuit, a circuit that converts an optical signal into an electrical signal for information processing, another information processing device, etc.), but is not limited thereto.

[0069] Also, in the example shown in FIG. 5, the first Mach-Zehnder interferometer and the second Mach-Zehnder interferometer included in the MZI matrix are alternately positioned in each of the row direction and the column direction of the MZI matrix. More specifically, in the example shown in FIG. 5, in all of the first to eighth rows, the first Mach-Zehnder interferometer and the second Mach-Zehnder interferometer are alternately positioned. Also, in this example, in all of the first to eighth columns, the first Mach-Zehnder interferometer and the second Mach-Zehnder interferometer are alternately positioned. When the second Mach-Zehnder interferometer is operated as the second unitary matrix operation circuit in this way, the second unitary matrix operation circuit operates as a unitary matrix operation circuit that performs a unitary matrix operation with seven optical signals as inputs and seven optical signals as outputs, as shown in FIG. 5. Then, when the arrangement of the second Mach-Zehnder interferometer shown in FIG. 5 is overlaid on the arrangement of the first Mach-Zehnder interferometer shown in FIG. 4, the arrangement of the MZI matrix is obtained. That is, the arrangements of the first Mach-Zehnder interferometer and the second Mach-Zehnder interferometer shown in FIGS. 4 and 5 are an example of an arrangement that divides the 8×8 Mach-Zehnder interferometers included in the optical switch circuit 10 so as to operate as the first unitary matrix operation circuit and the second unitary matrix operation circuit, respectively. However, in the example shown in FIG. 5, each of the Mach-Zehnder interferometers M11, M13, M15, M17, M28, M48, M68, M82, M84, M86, M88 hatched in FIG. 5 is a second Mach-Zehnder interferometer that is operated as a phase modulator (Bar state). That is, the optical intensity branching ratio in each of the Mach-Zehnder interferometers M11, M13, M15, M17, M28, M48, M68, M82, M84, M86, M88 hatched in FIG. 5 is 100:0 in Bar:Cross. On the other hand, the optical intensity branching ratio of each of the non-hatched Mach-Zehnder interferometers M22, M24, M26, M31, M33, M35, M37, M42, M44, M46, M51, M53, M55, M57, M62, M64, M66, M71, M73, M75, M77 in FIG. 5 becomes a desired ratio according to the desired unitary matrix operation.Furthermore, among the hatched Mach-Zehnder interferometers in FIG. 5 , the Mach-Zehnder interferometers M28, M48, M68, and M88 may be in a cross state. An optical signal input to the first port is phase-modulated and then output from the fourth port. An optical signal input to the second port is phase-modulated and then output from the third port. That is, in this case, the optical intensity branching ratio in each of the Mach-Zehnder interferometers M28, M48, M68, and M88 is Bar:Cross, or 0:100. As a result, the arrangement of the second Mach-Zehnder interferometers shown in FIG. 5 is an arrangement whose topology as an optical circuit is the same as that of a Bell-type optical circuit. That is, the 32 second Mach-Zehnder interferometers shown in FIG. 5 operate as a second unitary matrix calculation circuit.

[0070] Here, the first switching unit 11 can switch at least one of the seven second optical signals input to the optical switch circuit 10 shown in Fig. 5 to the first optical signal supplied from the first connection destination. This is because the first connection destination switching Mach-Zehnder interferometer A of the first switching unit 11 switches the connection destination from the second connection destination to the first connection destination in response to a control signal from the control device, thereby allowing the first optical signal to be input to the optical switch circuit 10. As a result, the optical circuit 1 can easily change the combination of seven optical signals input to the optical switch circuit 10, which operates as a second unitary matrix operation circuit, to a combination desired by the user, thereby improving versatility and user convenience.

[0071] 5 from the fourth connection destination to the third connection destination. This is because the second connection destination switching Mach-Zehnder interferometer B of the second switching unit 12 switches the connection destination from the fourth connection destination to the third connection destination in response to a control signal from the control device, thereby enabling the second optical signal after the unitary matrix operation to be output from the optical switch circuit 10 to the third connection destination. This allows the optical circuit 1 to easily output each of the optical signals after the second unitary matrix operation to a destination desired by the user, thereby improving versatility and user convenience.

[0072] 5 may be reversed. That is, the optical circuit 1 may be configured to receive an optical signal via the second switching unit 12 and output an optical signal after a unitary matrix operation via the first switching unit 11.

[0073] <Examples of Using Operation Example 1 and Operation Example 2> Here, examples of using the above-described operation example 1 and operation example 2 will be described.

[0074] For example, the optical circuit 1 can receive an optical signal from a port of a signal source of the optical signal for the optical switch and output the received optical signal to a port of an optical receiver to which the optical signal for the optical switch is input. In this case, the optical switch circuit 10 of the optical circuit 1 may operate as a PILOSS optical switch circuit or as a unitary matrix operation circuit, depending on the application. For example, in this case, when the optical switch circuit 10 operates as a PILOSS optical switch circuit, the optical circuit 1 functions as a circuit that switches optical signals.

[0075] Furthermore, for example, the optical circuit 1 can receive an optical signal from a port of a signal source of an optical signal for an optical switch and output the received optical signal to a port of an optical receiver to which an optical signal for a unitary matrix operation is input. In this case, the optical switch circuit 10 of the optical circuit 1 may operate as a PILOSS optical switch circuit or as a unitary matrix operation circuit, depending on the application. For example, in this case, when the optical switch circuit 10 operates as a PILOSS optical switch circuit, the optical circuit 1 functions as a receiver that receives information.

[0076] Furthermore, for example, the optical circuit 1 can receive an optical signal from a port of a signal source of an optical signal for unitary matrix operation and output the received optical signal to a port of an optical receiver to which an optical signal for optical switching is input. In this case, the optical switch circuit 10 of the optical circuit 1 may operate as a PILOSS optical switch circuit or as a unitary matrix operation circuit, depending on the application. For example, in this case, when the optical switch circuit 10 operates as a PILOSS optical switch circuit, the optical circuit 1 functions as a transmitter that transmits information.

[0077] Furthermore, for example, the optical circuit 1 can receive an optical signal from a port of a signal source of an optical signal for unitary matrix calculation and output the received optical signal to a port of an optical receiver to which the optical signal for unitary matrix calculation is input. In this case, the optical switch circuit 10 of the optical circuit 1 may operate as a PILOSS optical switch circuit or as a unitary matrix calculation circuit, depending on the application. For example, in this case, when the optical switch circuit 10 operates as a unitary matrix calculation circuit, the optical circuit 1 functions as a circuit that performs unitary matrix calculation. For example, in this case, when the optical switch circuit 10 operates as a PILOSS optical switch circuit, the optical circuit 1 functions as a circuit that performs circuit calibration to optimize operation as a PILOSS optical switch circuit.

[0078] Furthermore, for example, the optical circuit 1 can monitor the operation of the optical switch circuit 10 as a PILOSS optical switch circuit by utilizing the second switching unit 12. Specifically, in this case, the optical intensity branching ratio of the second connection destination switching Mach-Zehnder interferometer B included in the second switching unit 12 in the optical circuit 1 is set to 99:1 (Bar:Cross). As a result, the second connection destination switching Mach-Zehnder interferometer B can output 99% of the optical signal output from the optical switch circuit 10 from the third port and 1% of the optical signal from the fourth port. As a result, the information processing device monitoring the operation of the optical circuit 1 can monitor whether the operation of the optical circuit 1 is normal based on the 1% component. In this case, the optical signal input to the optical switch circuit 10 may be an optical signal for optical switching or an optical signal for unitary matrix calculation. Note that the optical intensity branching ratio may be other than 99:1.

[0079] Furthermore, for example, in the optical circuit 1, the third port and the fourth port of each of the Mach-Zehnder interferometers included in the MZI matrix described above may be configured to be connected to a cross waveguide CS as shown in Fig. 6. Fig. 6 is a diagram showing an example of an MZI matrix in which a cross waveguide CS is connected to the third port and the fourth port of each Mach-Zehnder interferometer. However, in Fig. 6, in order to prevent the diagram from becoming complicated, only the cross waveguides connected to the third port and the fourth port of each Mach-Zehnder interferometer included in the first row of the MZI matrix are indicated by the symbol CS.

[0080] 6, the cross waveguide CS connected to the third and fourth ports of a certain Mach-Zehnder interferometer is a waveguide that switches the output destination of the third port with the output destination of the fourth port. The cross waveguide CS may have a known configuration or a configuration to be developed in the future.

[0081] It is known that when the MZI matrix has the configuration shown in Fig. 6, the optical switch circuit 10 has a wider operating wavelength band as a PILOSS optical switch. In other words, this allows the optical circuit 1 to improve the versatility of its operation as a PILOSS optical switch.

[0082] As described above, the optical circuit 1 according to the embodiment includes an optical switch circuit 10 including 8×8 Mach-Zehnder interferometers arranged in an 8-row, 8-column matrix, a first switching unit 11 that switches the external connection destinations of each of M Mach-Zehnder interferometers among the eight Mach-Zehnder interferometers included in the first column of the MZI matrix, and a second switching unit 12 that switches the external connection destinations of each of L Mach-Zehnder interferometers among the eight Mach-Zehnder interferometers included in the eighth column of the MZI matrix. This allows the optical circuit 1 to be more versatile and convenient for users.

[0083] <Modification 1 of the Configuration of the Optical Circuit> Hereinafter, a description will be given of Modification 1 of the configuration of the optical circuit 1. FIG.

[0084] 7, the first switching unit 11 does not include the first connection destination switching Mach-Zehnder interferometer A1 and the first connection destination switching Mach-Zehnder interferometer A16, but includes fifteen first connection destination switching Mach-Zehnder interferometers A, namely, first connection destination switching Mach-Zehnder interferometer A2 to first connection destination switching Mach-Zehnder interferometer A15. Also, in this example, the second switching unit 12 does not include the second connection destination switching Mach-Zehnder interferometer B1 and the second connection destination switching Mach-Zehnder interferometer B16, but includes fifteen second connection destination switching Mach-Zehnder interferometers B, namely, second connection destination switching Mach-Zehnder interferometer B2 to second connection destination switching Mach-Zehnder interferometer B15. Note that the first switching unit 11 may also include the first connection destination switching Mach-Zehnder interferometer A1 and the first connection destination switching Mach-Zehnder interferometer A16. The second switching unit 12 may also include a second connection switching Mach-Zehnder interferometer B1 and a second connection switching Mach-Zehnder interferometer B16.

[0085] 7, when i is any of 2, 4, 6, 8, 10, 12, and 14, the fourth port of the second connection destination switching Mach-Zehnder interferometer Bi is connected to the third port of the second connection destination switching Mach-Zehnder interferometer Bi+1 via the amplitude modulator AS. In other words, in the example shown in FIG. 7, when i is any of 1 to 7, the fourth port of the second connection destination switching Mach-Zehnder interferometer B2i connected to the fourth port of the Mach-Zehnder interferometer located at row i, column 8 of the MZI matrix is ​​connected to the third port of the second connection destination switching Mach-Zehnder interferometer B2i+1 connected to the third port of the Mach-Zehnder interferometer located at row i+1, column 8 of the MZI matrix via the amplitude modulator AS. For example, the fourth port of the second connection destination switching Mach-Zehnder interferometer B2 is connected to the third port of the second connection destination switching Mach-Zehnder interferometer B3 via the amplitude modulator AS. In this case, the optical signal output from the fourth port is amplitude-modulated through the amplitude modulator AS and then input to the third port. That is, the optical circuit 1 shown in FIG. 7 further includes a plurality of amplitude modulators AS that modulate the amplitude of the optical signal output from some of the 14 second destination-switching Mach-Zehnder interferometers B and input the amplitude-modulated optical signal to the other parts of the 14 Mach-Zehnder interferometers. The amplitude modulator AS may also be configured to have a function of modulating the phase of the optical signal. In this case, the amplitude modulator AS modulates the phase as well as the amplitude of the optical signal.

[0086] The optical circuit 1 having the configuration shown in FIG. 7 can operate as a PILOSS optical switch circuit by outputting optical signals from each of the third port of the second connection destination switching Mach-Zehnder interferometer B2i and the fourth port of the second connection destination switching Mach-Zehnder interferometer B2i+1 when i is any one of 1 to 7.

[0087] On the other hand, the optical circuit 1 having the configuration shown in Figure 7 can be operated as a matrix operation circuit that performs three operations on an optical signal in sequence: a first unitary matrix operation, a diagonal matrix operation, and a second unitary matrix operation.

[0088] Here, Fig. 8 is a diagram showing an example of how the optical circuit 1 shown in Fig. 7 operates as a unitary matrix operation circuit that performs a first unitary matrix operation. Note that the operation of the optical switch circuit 10 shown in Fig. 8 as a unitary matrix operation circuit is the same as the operation described in Fig. 4, and therefore a description thereof will be omitted.

[0089] In the example shown in FIG. 8 , seven first-destination-switching Mach-Zehnder interferometers A, namely, first-destination-switching Mach-Zehnder interferometers A3, A4, A7, A8, A11, A12, and A15, are connected to a second destination. In this example, the second destination is a signal source of optical signals for matrix calculation. The optical circuit 1 performs a first unitary matrix calculation in the optical switch circuit 10 on the seven optical signals input from the signal source, and then outputs the optical signals after the first unitary matrix calculation to each of the second-destination-switching Mach-Zehnder interferometers B2, B5, B6, B9, B10, B13, and B14. The optical signals output to each of the second-destination-switching Mach-Zehnder interferometers B2, B5, B6, B9, B10, B13, and B14 are amplitude-modulated through an amplitude modulator AS. This amplitude modulation corresponds to the diagonal matrix calculation described above. After being amplitude modulated, the optical signal is input again to the optical switch circuit 10 via each of the second connection-switching Mach-Zehnder interferometers B3, B4, B7, B8, B11, B12, and B15, as shown in Fig. 9. Fig. 9 is a diagram showing an example of how the optical circuit 1 shown in Fig. 7 operates as a unitary matrix operation circuit that performs a second unitary matrix operation. In Fig. 9, the Mach-Zehnder interferometers operating as phase modulators are M11, M13, M15, M17, M31, M51, M71, M82, M84, M86, and M88, respectively. The optical circuit 1 performs a second unitary matrix operation on the optical signal re-input in the optical switch circuit 10, and then outputs the optical signal after the second unitary matrix operation from each of the first connection-switching Mach-Zehnder interferometers A2, A5, A6, A9, A10, A13, and A14. As described above, the optical circuit 1 can operate as a matrix operation circuit that sequentially performs three operations on the optical signal: a first unitary matrix operation, a diagonal matrix operation, and a second unitary matrix operation. As a result, the optical circuit 1 can perform any matrix operation using the optical signal, not limited to a unitary matrix operation. Note that the operation of the optical switch circuit 10 shown in FIG. 9 as a unitary matrix operation circuit is the same as the operation described in FIG. 5 except for the fact that the signal flows from the second row direction to the first row direction and the position where phase modulation is performed, and therefore will not be described here.Furthermore, in the operation as the unitary matrix calculation circuit shown in Figures 8 and 9, the functions of the first column and the eighth column may be interchanged. For example, in the example shown in Figure 8, M21, M41, and M61 may operate as phase modulators instead of M38, M58, and M78. For example, in the example shown in Figure 9, M28, M48, and M68 may operate as phase modulators instead of M31, M51, and M71. Furthermore, in the operation as the unitary matrix calculation circuit shown in Figures 8 and 9, some or all of the Mach-Zehnder interferometers in the first and eighth columns do not need to operate as phase modulators. For example, in the example shown in Figure 8, the optical intensity branching ratios of the Mach-Zehnder interferometers M21, M41, M61, M38, M58, and M78 are set to desired ratios according to the desired unitary matrix calculation. 9 , the optical intensity branching ratios of the Mach-Zehnder interferometers M31, M51, M71, M28, M48, and M68 are set to desired ratios in accordance with the desired unitary matrix calculation. In this case, the number of stages of the Mach-Zehnder interferometers that perform the unitary matrix calculation as the unitary matrix calculation circuit is increased from seven to eight. In this way, by increasing the number of stages of the Mach-Zehnder interferometers that perform the unitary matrix calculation, the optical circuit 1 improves the controllability of the unitary matrix calculation circuit, thereby making it possible to reduce calculation errors in the unitary matrix calculation.

[0090] <Modification 2 of the Optical Circuit Configuration> Modification 2 of the configuration of the optical circuit 1 will be described below with reference to Fig. 10. Fig. 10 is a diagram showing yet another example of the configuration of the optical circuit 1.

[0091] In the example shown in Fig. 10, the first switching unit 11 has the same configuration as the first switching unit 11 shown in Fig. 1. Furthermore, in this example, the second switching unit 12 has a configuration that combines the configuration of the second switching unit 12 shown in Fig. 1 and the configuration of the second switching unit 12 shown in Fig. 7. Therefore, in the second switching unit 12 shown in Fig. 10, when i is 2, 4, 6, 8, 10, 12, or 14, the fourth port of the second connection destination switching Mach-Zehnder interferometer Bi is connected to the third port of the second connection destination switching Mach-Zehnder interferometer Bi+1 via the amplitude modulator AS. Furthermore, the second switching unit 12 shown in Fig. 10 includes a second connection destination switching Mach-Zehnder interferometer B1 and a second connection destination switching Mach-Zehnder interferometer B16.

[0092] 10, the optical circuit 1 further includes a first connection destination adding unit 13 that adds a type of connection destination switchable by the first switching unit 11, and a second connection destination adding unit 14 that adds a type of connection destination switchable by the second switching unit 12. This allows the optical circuit 1 to realize, for example, all combinations of the operations and usage methods of the optical circuit 1 described above in response to control signals from a control device. As a result, the optical circuit 1 can improve versatility and user convenience.

[0093] The first connection destination adding unit 13 includes a Mach-Zehnder interferometer connected to each of some or all of the M Mach-Zehnder interferometers connected to the first switching unit 11. In the example shown in Fig. 10, the first connection destination adding unit 13 includes seven Mach-Zehnder interferometers, namely, Mach-Zehnder interferometer C1 to Mach-Zehnder interferometer C7.

[0094] The third port of the Mach-Zehnder interferometer C1 is connected to the second port of the first connection-destination-switching Mach-Zehnder interferometer A2. Therefore, by including the first connection-destination adding unit 13, the optical circuit 1 can switch the connection destination of the second port of the Mach-Zehnder interferometer M11 to one of three connection destinations: a connection destination connected to the first port of the first connection-destination-switching Mach-Zehnder interferometer A2, and a connection destination connected to each of the first and second ports of the Mach-Zehnder interferometer C1. This corresponds to increasing the number of connection destinations of the second port of the Mach-Zehnder interferometer M11 from two to three. In other words, the first connection-destination adding unit 13, which includes the Mach-Zehnder interferometer C1, can add a variety of connection destinations to the Mach-Zehnder interferometer M11. Note that, instead of being connected to the second port of the first connection destination switching Mach-Zehnder interferometer A2 by the third port, the Mach-Zehnder interferometer C1 may be connected to the second port of the first connection destination switching Mach-Zehnder interferometer A2 by the fourth port. Also, the third port of the Mach-Zehnder interferometer C1 may be connected to the first port of the first connection destination switching Mach-Zehnder interferometer A2.

[0095] Similarly, the third port of the Mach-Zehnder interferometer C2 is connected to the second port of the first connection destination switching Mach-Zehnder interferometer A5. This allows the first connection destination adding unit 13 equipped with the Mach-Zehnder interferometer C2 to add a type of connection destination for the Mach-Zehnder interferometer M31. Furthermore, the third port of the Mach-Zehnder interferometer C3 is connected to the second port of the first connection destination switching Mach-Zehnder interferometer A6. This allows the first connection destination adding unit 13 equipped with the Mach-Zehnder interferometer C3 to add a type of connection destination for the Mach-Zehnder interferometer M31. Furthermore, the third port of the Mach-Zehnder interferometer C4 is connected to the second port of the first connection destination switching Mach-Zehnder interferometer A9. This allows the first connection destination adding unit 13 equipped with the Mach-Zehnder interferometer C4 to add a type of connection destination for the Mach-Zehnder interferometer M51. Furthermore, the third port of the Mach-Zehnder interferometer C5 is connected to the second port of the first connection destination switching Mach-Zehnder interferometer A10. As a result, the first connection destination adding unit 13 including the Mach-Zehnder interferometer C5 can add a type of connection destination for the Mach-Zehnder interferometer M51. Furthermore, the third port of the Mach-Zehnder interferometer C6 is connected to the second port of the first connection destination switching Mach-Zehnder interferometer A13. As a result, the first connection destination adding unit 13 including the Mach-Zehnder interferometer C6 can add a type of connection destination for the Mach-Zehnder interferometer M71. Furthermore, the third port of the Mach-Zehnder interferometer C7 is connected to the second port of the first connection destination switching Mach-Zehnder interferometer A14. As a result, the first connection destination adding unit 13 including the Mach-Zehnder interferometer C7 can add a type of connection destination for the Mach-Zehnder interferometer M71.

[0096] The second connection destination adding unit 14 includes a Mach-Zehnder interferometer connected to each of some or all of the L Mach-Zehnder interferometers connected to the second switching unit 12. In the example shown in Fig. 10, the second connection destination adding unit 14 includes 14 Mach-Zehnder interferometers, namely, Mach-Zehnder interferometer D1 to Mach-Zehnder interferometer D14.

[0097] The first port of the Mach-Zehnder interferometer D1 is connected to the third port of the second connection-destination-switching Mach-Zehnder interferometer B2. Therefore, by including the second connection-destination adding unit 14, the optical circuit 1 can switch the connection destination of the fourth port of the Mach-Zehnder interferometer M18 to one of three connection destinations: a connection destination connected to the fourth port of the second connection-destination-switching Mach-Zehnder interferometer B2, and a connection destination connected to each of the first and second ports of the Mach-Zehnder interferometer D1. This corresponds to increasing the number of connection destinations of the fourth port of the Mach-Zehnder interferometer M18 from two to three. In other words, the second connection-destination adding unit 14, which includes the Mach-Zehnder interferometer D1, can add a variety of connection destinations to the Mach-Zehnder interferometer M18. In addition, instead of being configured to be connected to the third port of the second connection destination switching Mach-Zehnder interferometer B2 by the first port, the Mach-Zehnder interferometer D1 may be configured to be connected to the third port of the second connection destination switching Mach-Zehnder interferometer B2 by the second port.

[0098] Similarly, the first port of the Mach-Zehnder interferometer D2 is connected to the fourth port of the second connection destination switching Mach-Zehnder interferometer B3. This allows the second connection destination adding unit 14, which includes the Mach-Zehnder interferometer D2, to add a new type of connection destination for the Mach-Zehnder interferometer M28. Furthermore, the first port of the Mach-Zehnder interferometer D3 is connected to the third port of the second connection destination switching Mach-Zehnder interferometer B4. This allows the second connection destination adding unit 14, which includes the Mach-Zehnder interferometer D3, to add a new type of connection destination for the Mach-Zehnder interferometer M28. Furthermore, the first port of the Mach-Zehnder interferometer D4 is connected to the fourth port of the second connection destination switching Mach-Zehnder interferometer B5. This allows the second connection destination adding unit 14, which includes the Mach-Zehnder interferometer D4, to add a new type of connection destination for the Mach-Zehnder interferometer M38. Furthermore, the first port of the Mach-Zehnder interferometer D5 is connected to the third port of the second connection destination switching Mach-Zehnder interferometer B6. This allows the second connection destination adding unit 14 equipped with the Mach-Zehnder interferometer D5 to add a type of connection destination for the Mach-Zehnder interferometer M38. Furthermore, the first port of the Mach-Zehnder interferometer D6 is connected to the fourth port of the second connection destination switching Mach-Zehnder interferometer B7. This allows the second connection destination adding unit 14 equipped with the Mach-Zehnder interferometer D6 to add a type of connection destination for the Mach-Zehnder interferometer M48. Furthermore, the first port of the Mach-Zehnder interferometer D7 is connected to the third port of the second connection destination switching Mach-Zehnder interferometer B8. This allows the second connection destination adding unit 14 equipped with the Mach-Zehnder interferometer D7 to add a type of connection destination for the Mach-Zehnder interferometer M48. Furthermore, the first port of the Mach-Zehnder interferometer D8 is connected to the fourth port of the second connection destination switching Mach-Zehnder interferometer B9. This allows the second connection destination adding unit 14 equipped with the Mach-Zehnder interferometer D8 to add a type of connection destination for the Mach-Zehnder interferometer M58. Furthermore, the first port of the Mach-Zehnder interferometer D9 is connected to the third port of the second connection destination switching Mach-Zehnder interferometer B10.As a result, the second connection destination adding unit 14 including the Mach-Zehnder interferometer D9 can add a type of connection destination for the Mach-Zehnder interferometer M58. Furthermore, the first port of the Mach-Zehnder interferometer D10 is connected to the fourth port of the second connection destination switching Mach-Zehnder interferometer B11. As a result, the second connection destination adding unit 14 including the Mach-Zehnder interferometer D10 can add a type of connection destination for the Mach-Zehnder interferometer M68. Furthermore, the first port of the Mach-Zehnder interferometer D11 is connected to the third port of the second connection destination switching Mach-Zehnder interferometer B12. As a result, the second connection destination adding unit 14 including the Mach-Zehnder interferometer D11 can add a type of connection destination for the Mach-Zehnder interferometer M68. Furthermore, the first port of the Mach-Zehnder interferometer D12 is connected to the fourth port of the second connection destination switching Mach-Zehnder interferometer B13. As a result, the second connection destination adding unit 14 including the Mach-Zehnder interferometer D12 can add a type of connection destination for the Mach-Zehnder interferometer M78. Furthermore, the first port of the Mach-Zehnder interferometer D13 is connected to the third port of the second connection destination switching Mach-Zehnder interferometer B14. As a result, the second connection destination adding unit 14 including the Mach-Zehnder interferometer D13 can add a type of connection destination for the Mach-Zehnder interferometer M78. Furthermore, the first port of the Mach-Zehnder interferometer D14 is connected to the fourth port of the second connection destination switching Mach-Zehnder interferometer B15. As a result, the second connection destination adding unit 14 including the Mach-Zehnder interferometer D14 can add a type of connection destination for the Mach-Zehnder interferometer M88.

[0099] As described above, the optical circuit 1 may further include a first connection destination adding unit 13 that adds a type of connection destination switchable by the first switching unit 11, and a second connection destination adding unit 14 that adds a type of connection destination switchable by the second switching unit 12. In this case, the optical circuit 1 can realize, for example, all combinations of the operations and usage methods of the optical circuit 1 described above in response to control signals from a control device. As a result, the optical circuit 1 can improve versatility and user convenience.

[0100] The above-described contents may be combined in any manner.

[0101] As described above, the optical circuit 1 according to the embodiment includes an optical switch circuit 10 including 8×8 Mach-Zehnder interferometers arranged in an 8-row, 8-column matrix, a first switching unit 11 that switches the external connection destinations of M Mach-Zehnder interferometers among the eight Mach-Zehnder interferometers included in the first column of the MZI matrix, and a second switching unit 12 that switches the external connection destinations of L Mach-Zehnder interferometers among the eight Mach-Zehnder interferometers included in the eighth column of the MZI matrix. This allows the optical circuit 1 to be more versatile and convenient for users.

[0102] The input light used as the optical signal described above may be laser light, quantum light, or other light.

[0103] <Notes> [1] An optical circuit comprising: an optical switch circuit including N×N Mach-Zehnder interferometers arranged in a matrix of N rows and N columns, where N is an integer equal to or greater than 8; a first switching unit that switches external connection destinations of M Mach-Zehnder interferometers out of N Mach-Zehnder interferometers included in a first column of the matrix formed by the N×N Mach-Zehnder interferometers, where M is an integer equal to or greater than 1 and equal to or less than N; and a second switching unit that switches external connection destinations of L Mach-Zehnder interferometers out of N Mach-Zehnder interferometers included in an Nth column of the matrix, where L is an integer equal to or greater than 1 and equal to or less than N. [2] The optical circuit according to [1], wherein each of the N×N Mach-Zehnder interferometers has a first port and a second port that are provided on a first row side from the Nth column of the matrix toward the first column of the matrix and that can input and output an optical signal, and a third port and a fourth port that are provided on a second row side from the first column of the matrix toward the Nth column of the matrix and that can input and output an optical signal, wherein the first switching unit switches connection destinations between the first port of each of the M Mach-Zehnder interferometers and the second port of each of the M Mach-Zehnder interferometers, and the second switching unit switches connection destinations between the third port of each of the L Mach-Zehnder interferometers and the fourth port of each of the M Mach-Zehnder interferometers. [3] The optical circuit according to [2], wherein the first switching unit includes one or more Mach-Zehnder interferometers that switch connections between some or all of the first ports of each of the M Mach-Zehnder interferometers and the second ports of each of the M Mach-Zehnder interferometers, and the second switching unit includes one or more Mach-Zehnder interferometers that switch connections between some or all of the third ports of each of the L Mach-Zehnder interferometers and the fourth ports of each of the L Mach-Zehnder interferometers.[4] The optical circuit according to [3], further comprising: a first connection destination adding unit that adds a type of connection destination switchable by the first switching unit; and a second connection destination adding unit that adds a type of connection destination switchable by the second switching unit. [6] The optical circuit according to [5], wherein the first connection destination adding unit includes one or more Mach-Zehnder interferometers connected to some or all of the M Mach-Zehnder interferometers, and the second connection destination adding unit includes one or more Mach-Zehnder interferometers connected to some or all of the L Mach-Zehnder interferometers. [7] The optical circuit according to any one of [1] to [6], wherein two types of connection destinations switched by the first switching unit as connection destinations of the M Mach-Zehnder interferometers are signal sources of optical signals when two types of connection destinations switched by the second switching unit as connection destinations of the L Mach-Zehnder interferometers are output destinations of optical signals, and two types of connection destinations switched by the second switching unit as connection destinations of the L Mach-Zehnder interferometers are signal sources of optical signals when two types of connection destinations switched by the first switching unit as connection destinations of the M Mach-Zehnder interferometers are output destinations of optical signals. [8] The optical circuit according to any one of [1] to [7], wherein the first switching unit and the second switching unit switch the connection destination based on a control signal including information indicating an application of the optical switch circuit, and the N×N Mach-Zehnder interferometers switch their operations in response to the control signal.

[0104] The embodiments of this disclosure have been described in detail above with reference to the drawings, but the specific configuration is not limited to this embodiment, and may be changed, substituted, deleted, etc. as long as it does not deviate from the gist of this disclosure.

[0105] 1...optical circuit, 10...optical switch circuit, 11...first switching unit, 12...second switching unit, 13...first connection destination adding unit, 14...second connection destination adding unit, A, A1 to A16...first connection destination switching Mach-Zehnder interferometer, AS...amplitude modulator, B, B1 to B16...second connection destination switching Mach-Zehnder interferometer, C1 to C7...Mach-Zehnder interferometer, CS...intersecting waveguide, D1 to D14...Mach-Zehnder interferometer, M11 to M18, M21 to M28, M31 to M38, M41 to M48, M51 to M58, M61 to M68, M71 to M78, M81 to M88...Mach-Zehnder interferometer

Claims

1. An optical circuit comprising: an optical switch circuit including N x N Mach Zehnder interferometers arranged in a matrix of N rows and N columns, where N is an integer equal to or greater than 8; a first switching unit that switches the external connection of each of M Mach Zehnder interferometers out of the N Mach Zehnder interferometers included in a first column of the matrix formed by the N x N Mach Zehnder interferometers, where M is an integer equal to or greater than 1 and equal to or less than N; and a second switching unit that switches the external connection of each of L Mach Zehnder interferometers out of the N Mach Zehnder interferometers included in the Nth column of the matrix, where L is an integer equal to or greater than 1 and equal to or less than N.

2. The optical circuit according to claim 1, wherein each of the N×N Mach-Zehnder interferometers has a first port and a second port that are provided on a first row side from the Nth column of the matrix toward the first column of the matrix and capable of inputting and outputting an optical signal, and a third port and a fourth port that are provided on a second row side from the first column of the matrix toward the Nth column of the matrix and capable of inputting and outputting an optical signal, wherein the first switching unit switches the connection destinations of some or all of the first ports of each of the M Mach-Zehnder interferometers and the second ports of each of the M Mach-Zehnder interferometers, and the second switching unit switches the connection destinations of some or all of the third ports of each of the L Mach-Zehnder interferometers and the fourth ports of each of the M Mach-Zehnder interferometers.

3. The optical circuit of claim 2, wherein the first switching unit comprises one or more Mach Zehnder interferometers that switch the connections between some or all of the first ports of each of the M Mach Zehnder interferometers and the second ports of each of the M Mach Zehnder interferometers, and the second switching unit comprises one or more Mach Zehnder interferometers that switch the connections between some or all of the third ports of each of the L Mach Zehnder interferometers and the fourth ports of each of the L Mach Zehnder interferometers.

4. The optical circuit according to claim 3, wherein the second switching unit comprises a plurality of Mach-Zehnder interferometers that switch the connection destinations of some or all of the third ports of each of the L Mach-Zehnder interferometers and the fourth ports of each of the L Mach-Zehnder interferometers, and the optical circuit further comprises a plurality of amplitude modulators that modulate the amplitude of optical signals output from some of the plurality of Mach-Zehnder interferometers and input the amplitude-modulated optical signals to other portions of the plurality of Mach-Zehnder interferometers.

5. The optical circuit described in claim 1, further comprising: a first connection destination adding unit that adds a type of connection destination that can be switched by the first switching unit; and a second connection destination adding unit that adds a type of connection destination that can be switched by the second switching unit.

6. The optical circuit of claim 5, wherein the first connection destination adding unit comprises one or more Mach-Zehnder interferometers connected to some or all of the M Mach-Zehnder interferometers, and the second connection destination adding unit comprises one or more Mach-Zehnder interferometers connected to some or all of the L Mach-Zehnder interferometers.

7. The optical circuit according to claim 1, wherein the two types of connection destinations switched by the first switching unit as the connection destinations of the M Mach-Zehnder interferometers are signal sources of optical signals when the two types of connection destinations switched by the second switching unit as the connection destinations of the L Mach-Zehnder interferometers are output destinations of optical signals, and the two types of connection destinations switched by the second switching unit as the connection destinations of the L Mach-Zehnder interferometers are signal sources of optical signals when the two types of connection destinations switched by the first switching unit as the connection destinations of the M Mach-Zehnder interferometers are output destinations of optical signals.

8. The optical circuit according to claim 1, wherein the first switching unit and the second switching unit switch the connection destination based on a control signal including information indicating an application of the optical switch circuit, and the N x N Mach-Zehnder interferometers switch their operation in response to the control signal.

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