Optical computation device and method for adjusting mach-zehnder interferometer in optical computation device

Abstract

This optical computation device is provided with: a multi-stage MZI array (1) in which Mach-Zehnder interferometers (MZI) arranged in odd-numbered columns are arranged in even-numbered rows, and Mach-Zehnder interferometers arranged in even-numbered columns are arranged in odd-numbered rows in a matrix of a plurality of rows and a plurality of columns, and the Mach-Zehnder interferometers (MZI) are arranged in a rectangular shape; and monitor photodetectors (MPD) connected to first output ports Por3 of the Mach-Zehnder interferometers (MZI) arranged in the first row.

Description

Optical computing device and method for adjusting a Mach-Zehnder interferometer in the optical computing device

[0001] The present disclosure relates to an optical computing device having a multi-stage Mach-Zehnder interferometer (hereinafter referred to as MZI) array in which multi-stage MZIs are arranged in a rectangular shape, and a method for adjusting the MZIs in the optical computing device.

[0002] In an optical arithmetic circuit using analog computing technology that performs linear arithmetic using the interference of light traveling through an optical waveguide, a Clements-type mesh, which has a rectangular arrangement configuration that is compact and has low optical loss compared to a Reck-type mesh that has a triangular arrangement configuration, is disclosed in Non-Patent Document 1 as a multi-port interferometer mesh. The Clements-type mesh shown in Non-Patent Document 1 has N input and N output detectors and M rows of MZIs. There are N / 2 MZIs arranged in odd-numbered rows, and (N / 2-1) MZIs arranged in even-numbered rows.

[0003] Furthermore, calibration to compensate for phase errors due to manufacturing variations for each MZI in the Clements-type mesh shown in Non-Patent Document 1 is first performed along the longest diagonal line in the mesh, starting from the bottom MZI towards the top MZI, then along the line connecting the MZI in the row above the bottom MZI, excluding the bottom MZI, towards the top MZI, in the same way, along the line connecting the MZI in the last column, and similarly for the top MZI, and so on for the odd-numbered rows below.

[0004] Christopher Alexiev et al. “Calibrating rectangular interferometer meshes with external photodetectors” OSA Continuum vol.4,N0.11 / 15 Nov.2021.PP2892-2904

[0005] The Clements-type mesh shown in Non-Patent Document 1 is configured as described above, which results in a long calibration time for all MZIs. Furthermore, the Clements-type mesh shown in Non-Patent Document 1 is configured starting from the tail end of a plurality of connected MZIs, which makes the detected light intensity very weak depending on the initial conditions, making configuration difficult. Moreover, the Clements-type mesh shown in Non-Patent Document 1 always has an uncalibrated MZI in the optical waveguide path from the input node where light is input to the output node where light is output, which reduces the light detection accuracy at the output node.

[0006] The present disclosure is intended to solve the above-mentioned problems, and aims to provide an optical computing device having a multistage MZI array in which multiple MZIs are arranged in a rectangular shape, in which adjustment of the MZIs in the multistage MZI array can be performed in a short time.

[0007] The optical computing device according to the present disclosure includes a multi-stage MZI array in which Mach-Zehnder interferometers arranged in odd-numbered columns are arranged in even-numbered rows and Mach-Zehnder interferometers arranged in even-numbered columns are arranged in odd-numbered rows in a matrix of multiple rows and multiple columns, and the Mach-Zehnder interferometers are arranged in a rectangular shape, and a monitor photodetector connected to a first output port of the Mach-Zehnder interferometer arranged in the first row.

[0008] According to the present disclosure, adjustment of MZIs in a multi-stage MZI array configured in a rectangular shape in an optical computing device can be performed in a short time.

[0009] FIG. 1 is a schematic diagram conceptually showing a configuration of an optical arithmetic device according to a first embodiment; FIG. 2 is a diagram showing a configuration of an MZI in the optical arithmetic device according to the first embodiment; FIG. 3 is a diagram showing a configuration of an MZI in the optical arithmetic device according to the first embodiment; FIG. 4 is a flowchart showing a procedure in a method for adjusting an MZI in the optical arithmetic device according to the first embodiment; ３３1 is a schematic diagram showing a waveguide path of light for adjustment of an MZI in an optical arithmetic device according to a second embodiment. FIG. 2 is a schematic diagram conceptually showing a configuration of an optical arithmetic device according to a second embodiment. FIG. 3 is a flowchart showing a procedure in a method for adjusting an MZI in an optical arithmetic device according to a second embodiment. ９ and MZI ２５ 10 is a schematic diagram showing a waveguide path of light for adjustment to . It is a schematic diagram conceptually showing the configuration of an optical arithmetic device according to a third embodiment. It is a schematic diagram conceptually showing the configuration of an optical arithmetic device according to a fourth embodiment.

[0010] Embodiment 1. An optical arithmetic device according to embodiment 1 will be described with reference to Figures 1 to 6. The optical arithmetic device according to embodiment 1 is an optical arithmetic device equipped with an optical arithmetic circuit that uses analog computing technology to perform linear arithmetic using the interference of light traveling through an optical waveguide. The optical arithmetic circuit is composed of a Clements-type multistage MZI array that has a rectangular arrangement formed on the surface of a substrate.

[0011] The optical computing device according to the first embodiment includes a multistage MZI array 1 and a plurality of monitor photodetectors MPD. The multistage MZI array 1 is an integrated optical unitary converter that performs unitary conversion on an optical signal input to an input node and outputs the converted signal to an output node.

[0012] The multistage MZI array 1 is a matrix of multiple rows and columns, in which Mach-Zehnder interferometers (hereinafter referred to as MZIs) arranged in odd-numbered columns are arranged in even-numbered rows, and MZIs arranged in even-numbered columns are arranged in odd-numbered rows, with the MZIs arranged in a rectangular configuration. Each MZI has a first input port Port1, a second input port Port2, a first output port Port3, and a second output port Port4. The multiple monitor photodetectors MPD are photodiodes connected to the first output ports of the corresponding MZIs arranged in the first row.

[0013] In the multistage MZI array 1 of the first embodiment, if the number of MZIs arranged in the first column, that is, the number of MZIs in the input stage, is N (N is a natural number of 2 or more), the number of rows is 2N+1 and the number of columns, that is, the number of stages is 2N. The number of MZIs arranged in each row is N. The number of stages may be less than 2N.

[0014] The indexes for the MZIs are assigned as follows. That is, the index of the MZI in the first row, second column is set to 0, the index of the MZI arranged in the first row is increased by 1 in the order of columns, the MZI in the second row, first column is set after the MZI in the first row, Nth column, the index of the MZI arranged in the second row is increased by 1 in the order of columns, and in the same manner, the indexes are assigned in order up to [N x (2N + 1) - 1] up to the MZI in the 2N + 1 row, Nth column. In each row, the index of the MZI arranged has a smaller number when the number of columns is smaller. In the following description, when each MZI is specifically indicated, it is referred to as MZI ｉ Here, i is an index number ranging from 0 to [N×(2N+1)−1].

[0015] In the following explanation, as shown in Fig. 1, a 4 x 4 Clements-type multistage MZI array will be explained as an example, in which four MZIs are arranged in the input stage, the number of input nodes is 8, and the number of output nodes is 8. In Fig. 1, the numbers 0 to 35 enclosed in square frames indicate MZIs and also indicate the index numbers of the MZIs. In the multistage MZI array 1 shown in Fig. 1, N is 4, the number of rows is 9 (2N+1), the number of columns is 8 (2N), the input stage is the first column, and the output stage is the eighth column, which is the final column.

[0016] MZIs with indexes 0 to 4 are arranged on the first row, MZIs with indexes 5 to 7 on the second row, MZIs with indexes 8 to 11 on the third row, MZIs with indexes 12 to 15 on the fourth row, MZIs with indexes 16 to 19 on the fifth row, MZIs with indexes 20 to 23 on the sixth row, MZIs with indexes 24 to 27 on the seventh row, MZIs with indexes 28 to 31 on the eighth row, and MZIs with indexes 32 to 35 on the ninth row.

[0017] The number of MZIs arranged in each row is 4(N). Therefore, in all paths from the input node to the output node, the optical signal propagates through the same number of MZIs. As a result, in the multi-stage MZI array, the waveguide loss of each path is constant, resulting in good path symmetry.

[0018] The first input port Port1 and the second input port Port2 of the MZI arranged in the input stage are the MZIs arranged in the second row. ４ From the MZI placed on the fourth line １２ , MZI placed in the 6th row ２０ , MZI placed on the 8th row ２６ Input node x in order ０ ~x ７ The input node x is connected to ０ ~x ７ A light emitting element (not shown), which is a light emitting diode that outputs an optical signal, is connected to the input terminal.

[0019] Among the MZIs arranged in the 8th column, which is the final stage, the MZI arranged in the 1st row ３ The second output port Port4 of ０ Among the MZIs arranged in the final stage, the MZI arranged in the bottom 9th row is ３５ The first output port Port3 of ７ Among the MZIs arranged in the final stage, the MZI arranged in the third row between the first and ninth rows is connected to １１ , MZI placed in the fifth row １９ , MZI placed on the 7th row ２７ The first output port Port3 and the second output port Port4 of １ ~y ６ The output node y is connected to ０ ~y ７ A photodetector (not shown) that receives an optical signal is connected to the optical fiber 11.

[0020] MZI placed in the first row ０ , MZI １ , MZI ２ , MZI ３In each of them, the first input port Port1 corresponds to the monitor input node p ０ ~p ３ , and the second input port Port2 is connected to the MZI arranged in the adjacent front column in the second row. ４ ~MZI ７ The first output port Port3 is connected to the corresponding monitor photodetector MPD by an optical waveguide. ０ ~MPD ３ is connected to.

[0021] MZIs other than the input and output stages and the MZIs in the first and bottom rows ｉ In each, the first input port Port1 is connected by an optical waveguide to the second output port Port4 of the MZI arranged in the adjacent previous column in the adjacent previous row, and the second input port Port2 is connected by an optical waveguide to the first output port Port3 of the MZI arranged in the adjacent previous column in the adjacent subsequent row.

[0022] The MZI placed in the bottom 9th row ３２ , MZI ３３ , MZI ３４ , MZI ３５ In each of them, the first input port Port1 is connected to the MZI arranged in the adjacent front column in the eighth row. ２８ ~MZI ３１ The second input port Port2 is connected to the corresponding monitor input node p ４ From p ７ is connected to.

[0023] MZI ０ From MZI ３５ Each of them is one of the MZIs shown in Fig. 2 to Fig. 4, which has a configuration that can compensate for manufacturing variations in branching ratio (branching ratio variations) by adjustment. The MZI shown in Fig. 2 includes a first optical waveguide connecting the first input port Port1 and the first output port Port3, and a second optical waveguide connecting the second input port Port2 and the second output port Port4, and has a θ phase shifter.

[0024] The MZI shown in Fig. 3 includes a first optical waveguide connecting a first input port Port1 and a first output port Port3, and a second optical waveguide connecting a second input port Port2 and a second output port Port4, and has a φ phase shifter and a θ phase shifter. The MZI shown in Fig. 4 includes a first optical waveguide connecting a first input port Port1 and a first output port Port3, and a second optical waveguide connecting a second input port Port2 and a second output port Port4, and has a φ phase shifter, a θ phase shifter, and a ψ phase shifter.

[0025] The MZI shown in FIGS. 2 to 4 can be in two states: a through state in which input light to a first input port Port1 is output to a first output port Port3, and input light to a second input port Port2 is output to a second output port Port4, and a cross state in which input light to a first input port Port1 is output to a second output port Port4, and input light to a second input port Port2 is output to a first output port Port3.

[0026] 2 to 4 are fabricated using a semiconductor process, and the first optical waveguide and the second optical waveguide are formed by optical waveguides called silicon photonics, which have single crystal silicon as the core material. Note that silicon nitride (SiN), alumina, quartz, or the like may be used instead of single crystal silicon as the core material for forming the optical waveguide.

[0027] Monitor photodetector MPD ０ ~MPD ３ Each of the photodiodes has a pin structure and uses germanium as a material, which is compatible with the manufacturing process of silicon photonics. Note that instead of a photodiode using germanium, a photodiode formed by integrating compound semiconductors such as InGaAs by heterogeneous material bonding may also be used.

[0028] Next, a method for adjusting the MZI in the optical computing device according to the first embodiment will be described. ｉIn order to compensate for the branching ratio variation, the phase adjustment region is optimized. ｉ The procedure for adjusting the MZI for each phase will be described below.

[0029] The method for adjusting the MZI in the optical arithmetic device according to the first embodiment is to adjust the MZI to compensate for the phase error. ｉ For the MZI to be adjusted, ｉ The MZI to be adjusted in the optical waveguide path passing through ｉ The MZI arranged in the front row of the optical waveguide path is in a through state, and the MZI arranged in the rear row of the optical waveguide path is in a cross state. ｉ Adjustments are made to compensate for variations in the branching ratio in

[0030] The MZI adjustment method in the optical arithmetic device according to the first embodiment is to adjust the MZI arranged in the first row. ｉ is a monitor photodetector MPD that receives an optical signal at its first input port Port1 and is connected to its first output port Port3. ｋ The optical signal is output to the MZIs arranged in the second and subsequent rows to be adjusted. ｉ is an investigated MZI ｉ The adjustment is performed using only the MZI as the optical waveguide path. The adjustment method for the MZI in the optical computing device according to the first embodiment is performed in the order of the indexes from the MZI with index 0 to the MZI with index [N×(2N+1)−1].

[0031] Hereinafter, a specific procedure for adjusting the MZI in the optical arithmetic device according to the first embodiment will be described with reference to FIGS. 5 and 6 for an example in which N is set to 4. In step ST1, the MZI arranged in the first row ０ ~MZI ３ are adjusted in the order of index. ０ ~MZI ３ For each, the monitor input node p corresponding to the index order ０ ~p ３ Light is input to the corresponding monitor photodetector MPD ０ ~MPD ３ MZI ０ ~MZI３ Adjustments are made to compensate for the variations in the branching ratios of the MZIs. ０ ~MZI ３ Set each one to "through".

[0032] The optical waveguide path for adjustment is shown below: MZI to be adjusted ０ For the monitor input node p ０ and the photodetector is MPD ０ The p ０ →MZI ０ →MPD ０ In the following explanation, the optical waveguide paths are indicated by symbols to avoid the description becoming complicated. １ For p １ →MZI １ →MPD １ MZI to be adjusted ２ For p ２ →MZI ２ →MPD ２ MZI to be adjusted ３ For p ３ →MZI ３ →MPD ３ In step ST1, the MZI arranged in the first row ０ ~MZI ３ The adjustment is complete and the characteristics are known.

[0033] In step ST2, the MZI arranged in the second row ４ ~MZI ７ The input nodes x are adjusted in the order of their indices. ０ From the MZI of the input stage ４ Light is input to the first input port Port1 of the optical waveguide path to be adjusted. The MZIs arranged in the front row in the optical waveguide path passing through the adjustment target are set to the through state, and the MZIs arranged in the rear row are set to the cross state.

[0034] In the optical waveguide path shown below, MZI ｉ The state of MZI ｉ The through state is indicated as [T] and the cross state is indicated as [C] after the above. ４ For x ０→MZI ４ →MZI ０ [C] → MPD ０ .MZI ４ After adjustment, the MZI is set to the through state. ０ The MZI to be adjusted is also set to the through state. ５ For x ０ →MZI ４ [T] → MZI ０ [T] → MZI ５ →MZI １ [C] → MPD １ .MZI ５ After adjustment, the MZI is set to the through state. １ will also be ignored.

[0035] MZI to be adjusted ６ For x ０ →MZI ４ [T] → MZI ０ [T] → MZI ５ [T] → MZI １ [T] → MZI ６ →MZI ２ [C] → MPD ２ .MZI ６ After adjustment, the MZI is set to the through state. ２ After adjustment, the MZI to be adjusted is also set to the through state. ７ For x ０ →MZI ４ [T] → MZI ０ [T] → MZI ５ [T] → MZI １ [T] → MZI ６ [T] → MZI ２ [T] → MZI ７ →MZI ３ [C] → MPD ３ .MZI ７ After adjustment, the MZI is set to the through state. ３ will also be ignored.

[0036] In short, the MZI placed in the second row ４ ~MZI ７ are the input nodes x ０ Light is input from the monitor photodetector MPD ０ ~MPD ３The MZIs in the second row are monitored by the ４ ~MZI ７ In the adjustment of the input node x ０ The light output from the object to be adjusted is monitored by the monitor photodetector MPD. ０ ~MPD ３ Since the light passes through the MZI whose characteristics are already known and adjusted, the light detector MPD monitors only the characteristics of the MZI to be adjusted. ０ ~MPD ３ Each of these can be extracted more accurately.

[0037] In addition, since the light does not pass through the MZI whose state, whether through or cross, is unknown, all the light (except for the power lost due to waveguide loss) guided through the adjustment waveguide path is monitored by the monitor photodetector MPD ０ ~MPD ３ This allows for detection at each point, maximizing the light intensity during adjustment, thereby maximizing the signal-to-noise ratio and enabling highly accurate adjustment.

[0038] In step ST3, the MZI arranged in the third row ８ ~MZI １１ The input nodes x are adjusted in the order of their indices. １ From the MZI of the input stage ４ Light is input to the second input port Port2. Furthermore, every time the adjustment target is adjusted, the MZI arranged in the front row in the optical waveguide path passing through the adjustment target is set to the through state, and the MZI arranged in the rear row is set to the cross state.

[0039] MZI to be adjusted ８ For x １ →MZI ４ [T] → MZI ８ →MZI ５ [C] → MZI １ [C] → MPD １ MZI to be adjusted ９ For x １ →MZI ４ [T] → MZI ８ [T] → MZI ５ [T] → MZI ９ →MZI６ [C] → MZI ２ [C] → MPD ２ .

[0040] MZI to be adjusted １０ For x １ →MZI ４ [T] → MZI ８ [T] → MZI ５ [T] → MZI ９ [T] → MZI ６ [T] → MZI １０ →MZI ７ [C] → MZI ３ [C] → MPD ３ MZI to be adjusted １１ For x １ →MZI ４ [T] → MZI ８ [T] → MZI ５ [T] → MZI ９ [T] → MZI ６ [T] → MZI １０ [T] → MZI ７ [T] → MZI １１ →y １ MZI to be adjusted １１ is the output node y １ In the following description, the output node shown in the optical waveguide path for adjustment includes the photodetector connected to the output node.

[0041] In short, the MZI placed in the third row ８ ~MZI １１ are the input nodes x １ Light is input from the monitor photodetector MPD １ ~MPD ３ , output node y １ The MZIs in the third row are monitored by the photodetectors connected to the ８ ~MZI １１In the adjustment of the optical fiber, the light passes through an MZI whose characteristics are known and already adjusted, so that it is possible to extract with high accuracy only the characteristics of the MZI to be adjusted. Also, since the light does not pass through an MZI whose state, whether through or cross, is unknown, all the light guided through the adjustment waveguide path can be detected, and the optical intensity in the adjustment can be maximized. This maximizes the signal-to-noise ratio, enabling highly accurate adjustment.

[0042] In step ST4, the MZI arranged in the fourth row １２ ~MZI １５ The input nodes x are adjusted in the order of their indices. ２ From the MZI of the input stage １２ Light is input to the first input port Port1 of the adjustment target. Furthermore, each time the adjustment target is adjusted, the MZI arranged in the front row in the optical waveguide path passing through the adjustment target is set to the through state, and the MZI arranged in the rear row is set to the cross state.

[0043] MZI to be adjusted １２ For x ２ →MZI １２ →MZI ８ [C] → MZI ５ [C] → MZI １ [C] → MPD １ MZI to be adjusted １３ For x ２ →MZI １２ [T] → MZI ８ [T] → MZI １３ →MZI ９ [C] → MZI ６ [C] → MZI ２ [C] → MPD ２ .

[0044] MZI to be adjusted １４ For x ２ →MZI １２ [T] → MZI ８ [T] → MZI １３ [T] → MZI ９ [T] → MZI １４ →MZI １０ [C] → MZI ７ [C] → MZI ３ [C] → MPD ３MZI to be adjusted １５ For x ２ →MZI １２ [T] → MZI ８ [T] → MZI １３ [T] → MZI ９ [T] → MZI １４ [T] → MZI １０ [T] → MZI １5 →MZI １１ [C] → y １ .

[0045] In short, the MZI placed in the fourth row １２ ~MZI １５ are the input nodes x ２ Light is input from the monitor photodetector MPD １ ~MPD ３ , output node y １ The MZIs arranged in the fourth row are monitored by the photodetectors connected to the １２ ~MZI １５ In the adjustment of the optical fiber, the light passes through an MZI whose characteristics are known and already adjusted, so that it is possible to extract with high accuracy only the characteristics of the MZI to be adjusted. Also, since the light does not pass through an MZI whose state, whether through or cross, is unknown, all the light guided through the adjustment waveguide path can be detected, and the optical intensity in the adjustment can be maximized. This maximizes the signal-to-noise ratio, enabling highly accurate adjustment.

[0046] In step ST5, the MZI arranged in the fifth row １６ ~MZI １９ The input nodes x are adjusted in the order of their indices. ３ From the MZI of the input stage １２ Light is input to the second input port Port2. Furthermore, every time the adjustment target is adjusted, the MZI arranged in the front row in the optical waveguide path passing through the adjustment target is set to the through state, and the MZI arranged in the rear row is set to the cross state.

[0047] MZI to be adjusted １６ For x ３ →MZI １２ [T] → MZI １６ →MZI １３[C] → MZI ９ [C] → MZI ６ [C] → MZI ２ [C] → MPD ２ MZI to be adjusted １７ For x ３ →MZI １２ [T] → MZI １６ [T] → MZI １３ [T] → MZI １７ →MZI １４ [C] → MZI １０ [C] → MZI ７ [C] → MZI ３ [C] → MPD ３ .

[0048] MZI to be adjusted １８ For x ３ →MZI １２ [T] → MZI １６ [T] → MZI １３ [T] → MZI １７ [T] → MZI １４ [T] → MZI １８ →MZI １5 [C] → MZI １１ [C] → y １ MZI to be adjusted １９ For x ３ →MZI １２ [T] → MZI １６ [T] → MZI １３ [T] → MZI １７ [T] → MZI １４ [T] → MZI １８ [T] → MZI １5 [T] → MZI １９ →y ３ .

[0049] In short, the MZI placed on the fifth row １６ ~MZI １９ are the input nodes x ３ Light is input from the monitor photodetector MPD ２ , M.P.D. ３ , output node y １ , y ３ The MZIs arranged in the fifth row are monitored by the photodetectors connected to the １６ ~MZI １９In the adjustment of the optical fiber, the light passes through an MZI whose characteristics are known and already adjusted, so that it is possible to extract with high accuracy only the characteristics of the MZI to be adjusted. Also, since the light does not pass through an MZI whose state, whether through or cross, is unknown, all the light guided through the adjustment waveguide path can be detected, and the optical intensity in the adjustment can be maximized. This maximizes the signal-to-noise ratio, enabling highly accurate adjustment.

[0050] In step ST6, the MZI arranged in the 6th row ２０ ~MZI ２３ The input nodes x are adjusted in the order of their indices. ４ From the MZI of the input stage ２０ Light is input to the first input port Port1 of the adjustment target. Furthermore, each time the adjustment target is adjusted, the MZI arranged in the front row in the optical waveguide path passing through the adjustment target is set to the through state, and the MZI arranged in the rear row is set to the cross state.

[0051] MZI to be adjusted ２０ For x ４ →MZI ２０ →MZI １６ [C] → MZI １３ [C] → MZI ９ [C] → MZI ６ [C] → MZI ２ [C] → MPD ２ MZI to be adjusted ２１ For x ４ →MZI ２０ [T] → MZI １６ [T] → MZI ２１ →MZI １７ [C] → MZI １４ [C] → MZI １０ [C] → MZI ７ [C] → MZI ３ [C] → MPD ３ .

[0052] MZI to be adjusted ２２ For x ４ →MZI ２０ [T] → MZI １６ [T] → MZI ２１ [T] → MZI １７ [T] → MZI２２ →MZI １８ [C] → MZI １5 [C] → MZI １１ [C] → y １ MZI to be adjusted ２３ For x ４ →MZI ２０ [T] → MZI １６ [T] → MZI ２１ [T] → MZI １７ [T] → MZI ２２ [T] → MZI １８ [T] → MZI ２３ →MZI １９ →y ３ .

[0053] In short, the MZI placed on the 6th row ２０ ~MZI ２３ are the input nodes x ４ Light is input from the monitor photodetector MPD ２ , M.P.D. ３ , output node y １ , y ３ The MZIs arranged in the sixth row are monitored by the photodetectors connected to the ２０ ~MZI ２３ In the adjustment of the optical fiber, the light passes through an MZI whose characteristics are known and already adjusted, so that it is possible to extract with high accuracy only the characteristics of the MZI to be adjusted. Also, since the light does not pass through an MZI whose state, whether through or cross, is unknown, all the light guided through the adjustment waveguide path can be detected, and the optical intensity in the adjustment can be maximized. This maximizes the signal-to-noise ratio, enabling highly accurate adjustment.

[0054] In step ST7, the MZI arranged in the 7th row ２４ ~MZI ２７ The input nodes x are adjusted in the order of their indices. ５ From the MZI of the input stage ２０ Light is input to the second input port Port2. Furthermore, every time the adjustment target is adjusted, the MZI arranged in the front row in the optical waveguide path passing through the adjustment target is set to the through state, and the MZI arranged in the rear row is set to the cross state.

[0055] MZI to be adjusted ２４ For x ５ →MZI ２０ [T] → MZI ２４ →MZI ２１ [C] → MZI １７ [C] → MZI １４ [C] → MZI １０ [C] → MZI ７ [C] → MZI ３ [C] → MPD ３ MZI to be adjusted ２５ For x ５ →MZI ２０ [T] → MZI ２４ [T] → MZI ２１ [T] → MZI ２５ →MZI ２２ [C] → MZI １８ [C] → MZI １5 [C] → MZI １１ [C] → y １ .

[0056] MZI to be adjusted ２６ For x ５ →MZI ２０ [T] → MZI ２４ [T] → MZI ２１ [T] → MZI ２５ [T] → MZI ２２ [T] → MZI ２６ →MZI ２３ [C] → MZI １９ [C] → y ３ MZI to be adjusted ２７ For x ５ →MZI ２０ [T] → MZI ２４ [T] → MZI ２１ [T] → MZI ２５ [T] → MZI ２２ [T] → MZI ２６ [T] → MZI ２３ [T] → MZI ２７ →y ５ .

[0057] In short, the MZI placed on the 7th row ２４ ~MZI ２７ are the input nodes x ５ Light is input from the monitor photodetector MPD３ , output node y １ , y ３ , y ５ The MZIs arranged in the seventh row are monitored by the photodetectors connected to the ２４ ~MZI ２７ In the adjustment of the optical fiber, the light passes through an MZI whose characteristics are known and already adjusted, so that it is possible to extract with high accuracy only the characteristics of the MZI to be adjusted. Also, since the light does not pass through an MZI whose state, whether through or cross, is unknown, all the light guided through the adjustment waveguide path can be detected, and the optical intensity in the adjustment can be maximized. This maximizes the signal-to-noise ratio, enabling highly accurate adjustment.

[0058] In step ST8, the MZI arranged in the 8th row ２８ ~MZI ３１ The input nodes x are adjusted in the order of their indices. ６ From the MZI of the input stage ２８ Light is input to the first input port Port1 of the adjustment target. Furthermore, each time the adjustment target is adjusted, the MZI arranged in the front row in the optical waveguide path passing through the adjustment target is set to the through state, and the MZI arranged in the rear row is set to the cross state.

[0059] MZI to be adjusted ２８ For x ６ →MZI ２８ →MZI ２４ [C] → MZI ２１ [C] → MZI １７ [C] → MZI １４ [C] → MZI １０ [C] → MZI ７ [C] → MZI ３ [C] → MPD ３ MZI to be adjusted ２９ For x ６ →MZI ２８ [T] → MZI ２４ [T] → MZI ２９ →MZI ２５ [C] → MZI ２２ [C] → MZI １８ [C] → MZI １5 [C] → MZI １１ [C] → y１ .

[0060] MZI to be adjusted ３０ For x ６ →MZI ２８ [T] → MZI ２４ [T] → MZI ２９ [T] → MZI ２５ [T] → MZI ３０ →MZI ２６ [C] → MZI ２３ [C] → MZI １９ [C] → y ３ MZI to be adjusted ３１ For x ６ →MZI ２８ [T] → MZI ２４ [T] → MZI ２９ [T] → MZI ２５ [T] → MZI ３０ [T] → MZI ２６ [T] → MZI ３１ →MZI ２７ [C] → y ５ .

[0061] In short, the MZI placed on the 8th row ２８ ~MZI ３１ are the input nodes x ６ Light is input from the monitor photodetector MPD ３ , output node y １ , y ３ , y ５ The MZIs arranged in the 8th row are monitored by the photodetectors connected to the ２８ ~MZI ３１ In the adjustment of the optical fiber, the light passes through an MZI whose characteristics are known and already adjusted, so that it is possible to extract with high accuracy only the characteristics of the MZI to be adjusted. Also, since the light does not pass through an MZI whose state, whether through or cross, is unknown, all the light guided through the adjustment waveguide path can be detected, and the optical intensity in the adjustment can be maximized. This maximizes the signal-to-noise ratio, enabling highly accurate adjustment.

[0062] In step ST9, the MZI arranged in the 9th row ３２ ~MZI ３５The input nodes x are adjusted in the order of their indices. ７ From the MZI of the input stage ２８ Light is input to the second input port Port2. Furthermore, every time the adjustment target is adjusted, the MZI arranged in the front row in the optical waveguide path passing through the adjustment target is set to the through state, and the MZI arranged in the rear row is set to the cross state.

[0063] MZI to be adjusted ３２ For x ７ →MZI ２８ [T] → MZI ３２ →MZI ２９ [C] → MZI ２５ [C] → MZI ２２ [C] → MZI １８ [C] → MZI １５ [C] → MZI １１ [C] → y １ MZI to be adjusted ３３ For x ７ →MZI ２８ [T] → MZI ３２ [T] → MZI ２９ [T] → MZI ３３ →MZI ３０ [C] → MZI ２６ [C] → MZI ２３ [C] → MZI １９ [C] → y ３ The MZI to be adjusted is shown in FIG. ３３ The optical waveguide path for adjustment to is shown by a bold line.

[0064] MZI to be adjusted ３４ For x ７ →MZI ２８ [T] → MZI ３２ [T] → MZI ２９ [T] → MZI ３３ [T] → MZI ３０ [T] → MZI ３４ →MZI ３１ [C] → MZI ２７ [C] → y ５ MZI to be adjusted ３５ For x ７ →MZI ２８ [T] → MZI ３２ [T] → MZI２９ [T] → MZI ３３ [T] → MZI ３０ [T] → MZI ３４ [T] → MZI ３１ [T] → MZI ３５ →y ７ .

[0065] In short, the MZI placed on the 9th line ３２ ~MZI ３５ Each input node x ５ Light is input from the output node y １ , y ３ , y ５ , y ７ The MZIs arranged in the 9th row are monitored by the photodetectors connected to the ３２ ~MZI ３５ In the adjustment of the optical fiber, the light passes through an MZI whose characteristics are known and already adjusted, so that it is possible to extract with high accuracy only the characteristics of the MZI to be adjusted. Also, since the light does not pass through an MZI whose state, whether through or cross, is unknown, all the light guided through the adjustment waveguide path can be detected, and the optical intensity in the adjustment can be maximized. This maximizes the signal-to-noise ratio, enabling highly accurate adjustment.

[0066] In addition, the MZI to be adjusted ｉ In short, the MZI arranged in the first row ｉ is a direct monitor photodetector MPD ｋ and the MZIs arranged in the second and subsequent rows are monitored and adjusted by ｉ When adjusting the MZI to be adjusted, ｉ The adjustment can be performed by placing only the adjusted MZIs in the optical waveguide path through which the adjustment light passes, with the state of the MZIs being clearly defined as being in the through state or cross state. ｉ When adjusting MZI, start from the second line and adjust ｉ The index of the MZI to be adjusted is adjusted in the order of ｉ The adjustment can be performed by placing only the adjusted MZI in the optical waveguide path through which the adjustment light passes.

[0067] The optical arithmetic device according to the first embodiment is a multi-stage MZI array 1 in which MZIs arranged in odd-numbered columns are arranged in even-numbered rows, and MZIs arranged in even-numbered columns are arranged in odd-numbered rows in a matrix of multiple rows and multiple columns, and the MZIs are arranged in a rectangular shape; and a monitor photodetector MPD connected to the first output port of the MZI arranged in the first row. ｋ With this, MPD ｋ All of the MZIs that make up the system can be adjusted in a short time.

[0068] Also, the monitor photodetector MPD ｋ The MZI to be adjusted is monitored by ｉ For the MZI to be adjusted, ｉ Therefore, the number of adjusted MZIs present in the optical waveguide path through which light passes can be reduced, and the loss in the optical waveguide path can be reduced. As a result, the optical intensity to be monitored can be increased, for example, maximized, the signal-to-noise ratio can be maximized, and the MZI can be adjusted with high precision.

[0069] Moreover, in the optical arithmetic device according to the first embodiment, the MZI arranged in the first row ｉ is a direct monitor photodetector MPD ｋ and the MZIs arranged in the second and subsequent rows can be monitored and adjusted by ｉ For the adjustment of ｉ Since there are adjusted MZIs with known characteristics in the optical waveguide path through which the adjustment light passes, and no unadjusted MZIs exist, it is possible to precisely extract only the characteristics of the MZIi to be adjusted, and highly accurate adjustment of the MZI is possible.

[0070] Furthermore, the optical arithmetic device according to the first embodiment is ｉ Since there is no MZI whose state is unknown, whether it is a through state or a cross state, in the optical waveguide path through which the adjustment light passes, the MZI to be adjusted can be adjusted. ｉ The optical detector MPD efficiently monitors the light propagating through the optical waveguide path through which the light for adjusting the ｋ Alternatively, since it can be detected by a photodetector connected to the output node, the monitored light intensity can be increased, for example, maximized, the signal-to-noise ratio can be maximized, and the MZI can be adjusted with high precision.

[0071] Second Embodiment An optical arithmetic device according to a second embodiment will be described with reference to Figs. 7 to 9. The optical arithmetic device according to the second embodiment further comprises an MZI arranged in the bottom row in addition to the optical arithmetic device according to the first embodiment. ｉ 7 to 9, the difference is that a second monitor photodetector MPD is provided which is connected to the second output port Port4 of the MZI arranged in the first row, but other points are the same. Therefore, the following explanation will focus on the differences. In the following explanation, the monitor photodetector MPD connected to the first output port of the MZI arranged in the first row will be referred to as the first monitor photodetector. In Figures 7 to 9, the same reference numerals as those in Figures 1 to 6 indicate the same or corresponding parts.

[0072] The MZI placed in the bottom 9th row ３２ , MZI ３３ , MZI ３４ , MZI ３５ In each of them, the first input port Port1 is connected to the MZI arranged in the adjacent front column in the eighth row. ２８ ~MZI ３１ The second input port Port2 is connected to the corresponding monitor input node p ４ From p ７ , and the second output port Port4 corresponds to the second monitor photodetector MPD ４ ~MPD ７ is connected to.

[0073] Second monitor photodetector MPD ４ ~MPD ７ Each of the photodiodes has a pin structure and uses germanium as a material, which is compatible with the manufacturing process of silicon photonics. Note that instead of a photodiode using germanium, a photodiode formed by integrating compound semiconductors such as InGaAs by heterogeneous material bonding may also be used.

[0074] Next, a method for adjusting the MZI in the optical arithmetic device according to the second embodiment will be described. The multiple rows (2N+1) in the multi-stage MZI array 1 are divided into two, a first half (N+1) and a second half (N), and adjustments are made to simultaneously compensate for branching ratio variations in the MZIs arranged in the first half rows and the MZIs arranged in the second half rows, from the first row to the bottom row (N+1) of the first half, and from the bottom row (2N+1) to the top row (N+2) of the second half, and adjustments are made to the MZIs arranged in each row, with only the MZIs that have been checked being used as the optical waveguide path.

[0075] The MZIs in the first half of the multi-stage MZI array 1 are adjusted in the order of index from the MZI with index 0 to the MZI with index [N×(N+1)−1], and the MZIs in the second half are adjusted in the order of index from the MZI with index [N×(2N+1)−1] to the MZI with index [N×(N+1)].

[0076] Hereinafter, a specific procedure for adjusting the MZI in the optical arithmetic device according to the second embodiment will be described with reference to FIGS. 8 and 9 for an example in which N is set to 4. The MZI arranged in the first row in the first half of the multi-stage MZI array 1 ０ ~MZI ３ and the MZI placed on the 9th line in the latter half ３２ ~MZI ３５ The adjustment of MZI placed in the second row in the first half is adjusted in parallel. ４ ~MZI ７ and the MZI placed on the 8th line in the latter half ２８ ~MZI ３１ Adjust the above in parallel.

[0077] MZI placed on the third row in the first half ８ ~MZI １１ and the MZI placed on the 7th line in the latter half ２４ ~MZI ２７ The adjustment of MZI placed in the fourth row in the first half is adjusted in parallel. １２ ~MZI １５ and the MZI placed on the 6th line in the latter half ２０ ~MZI ２３Adjust the above in parallel.

[0078] MZI placed on the 5th row １６ ~MZI １９ The first half MZI in the multi-stage MZI array 1 is adjusted. ０ ~MZI １９ The adjustment of the MZI is performed in accordance with the method for adjusting the MZI in the optical arithmetic device according to the first embodiment. ０ ~MZI １９ Similarly, this is performed in steps ST1 to ST5, so the explanation will be omitted.

[0079] In step ST1, the MZI arranged in the first row ０ ~MZI ３ At the same time, the MZI placed in the 9th row corresponds to ３２ ~MZI ３５ are adjusted in the order of index. ３２ For p ４ →MZI ３２ →MPD ４ MZI to be adjusted ３３ For p ５ →MZI ３３ →MPD ５ MZI to be adjusted ３４ For p ６ →MZI ３４ →MPD ６ MZI to be adjusted ３５ For p ７ →MZI ３５ →MPD ７ In step ST1, the MZI placed in the 9th row ３２ ~MZI ３５ The adjustment is complete and the characteristics are known.

[0080] In step ST2, the MZI arranged in the second row ４ ~MZI ７ At the same time, the MZI placed in the 8th row corresponds to ２８ ~MZI ３１ The input nodes x are adjusted in the order of their indices. ７ From the MZI of the input stage ２８Light is input to the second input port Port2. Furthermore, every time the adjustment target is adjusted, the MZI arranged in the front row in the optical waveguide path passing through the adjustment target is set to the through state, and the MZI arranged in the rear row is set to the cross state.

[0081] MZI to be adjusted ２８ For x ７ →MZI ２８ →MZI ３２ [C] → MPD ４ .MZI ２８ After adjustment, the MZI is set to the through state. ３２ The MZI to be adjusted is also set to the through state. ２９ For x ７ →MZI ２８ [T] → MZI ２９ →MZI ３２ [T] → MZI ３３ [C] → MPD ５ .MZI ２９ After adjustment, the MZI is set to the through state. ３３ will also be ignored.

[0082] MZI to be adjusted ３０ For x ７ →MZI ２８ [T] → MZI ３２ [T] → MZI ２９ [T] → MZI ３３ [T] → MZI ３０ →MZI ３４ [C] → MPD ６ .MZI ３０ After adjustment, the MZI is set to the through state. ３４ After adjustment, the MZI to be adjusted is also set to the through state. ３１ For x ７ →MZI ２８ [T] → MZI ３２ [T] → MZI ２９ [T] → MZI ３３ [T] → MZI ３０ [T] → MZI ３４ [T] → MZI ３１ →MZI ３５ [C] → MPD ７ .

[0083] In short, the MZI placed on the 8th row ２８~MZI ３１ are the input nodes x ７ Light is input from the second monitor photodetector MPD ４ ~MPD ７ The MZIs arranged in the 8th row are monitored by the photodetectors connected to the ２８ ~MZI ３１ In the adjustment of the optical fiber, the light passes through an MZI whose characteristics are known and already adjusted, so that it is possible to extract with high accuracy only the characteristics of the MZI to be adjusted. Also, since the light does not pass through an MZI whose state, whether through or cross, is unknown, all the light guided through the adjustment waveguide path can be detected, and the optical intensity in the adjustment can be maximized. This maximizes the signal-to-noise ratio, enabling highly accurate adjustment.

[0084] In step ST3, the MZI arranged in the third row ８ ~MZI １１ At the same time, the MZI placed in the 7th row corresponds to ２４ ~MZI ２７ The input nodes x are adjusted in the order of their indices. ６ From the MZI of the input stage ２８ Light is input to the first input port Port1 of the adjustment target. Furthermore, every time the adjustment target is adjusted, the MZI arranged in the front row in the optical waveguide path passing through the adjustment target is set to the through state, and the MZI arranged in the rear row is set to the cross state.

[0085] MZI to be adjusted ２４ For x ６ →MZI ２８ [T] → MZI ２４ →MZI ２９ [C] → MZI ３３ [C] → MPD ５ MZI to be adjusted ２５ For x ６ →MZI ２８ [T] → MZI ２４ [T] → MZI ２９ [T] → MZI ２５ →MZI ３０ [C] → MZI ３４ [C] → MPD ６ In FIG. 9, the MZI to be adjusted in step ST3９ and the MZI to be adjusted ３３ The optical waveguide path for adjustment to is shown by a bold line.

[0086] MZI to be adjusted ２６ For x ６ →MZI ２８ [T] → MZI ２４ [T] → MZI ２９ [T] → MZI ２５ [T] → MZI ３０ [T] → MZI ２６ →MZI ３１ [C] → MZI ３５ [C] → MPD ７ MZI to be adjusted ２７ For x ６ →MZI ２８ [T] → MZI ２４ [T] → MZI ２９ [T] → MZI ２５ [T] → MZI ３０ [T] → MZI ２６ [T] → MZI ３１ [T] → MZI ２７ →y ６ .

[0087] In short, the MZI placed on the 7th row ２４ ~MZI ２７ are the input nodes x ６ Light is input from the second monitor photodetector MPD ５ ~MPD ７ , output node y ６ The MZIs arranged in the seventh row are monitored by the photodetectors connected to the ２４ ~MZI ２７ In the adjustment of the optical fiber, the light passes through an MZI whose characteristics are known and already adjusted, so that it is possible to extract with high accuracy only the characteristics of the MZI to be adjusted. Also, since the light does not pass through an MZI whose state, whether through or cross, is unknown, all the light guided through the adjustment waveguide path can be detected, and the optical intensity in the adjustment can be maximized. This maximizes the signal-to-noise ratio, enabling highly accurate adjustment.

[0088] In step ST4, the MZI arranged in the fourth row １２ ~MZI１５ At the same time, the MZI placed in the 6th row corresponds to ２０ ~MZI ２３ The input nodes x are adjusted in the order of their indices. ５ From the MZI of the input stage ２０ Light is input to the second input port Port2. Furthermore, every time the adjustment target is adjusted, the MZI arranged in the front row in the optical waveguide path passing through the adjustment target is set to the through state, and the MZI arranged in the rear row is set to the cross state.

[0089] MZI to be adjusted ２０ For x ５ →MZI ２０ →MZI ２４ [C] → MZI ２９ [C] → MZI ３３ [C] → MPD ５ MZI to be adjusted ２１ For x ５ →MZI ２０ [T] → MZI ２４ [T] → MZI ２１ →MZI ２５ [C] → MZI ３０ [C] → MZI ３４ [C] → MPD ６ .

[0090] MZI to be adjusted ２２ For x ５ →MZI ２０ [T] → MZI ２４ [T] → MZI ２１ [T] → MZI ２５ [T] → MZI ２２ →MZI ２６ [C] → MZI ３１ [C] → MZI ３５ [C] → MPD ７ MZI to be adjusted ２３ For x ５ →MZI ２０ [T] → MZI ２４ [T] → MZI ２１ [T] → MZI ２５ [T] → MZI ２２ [T] → MZI ２６ [T] → MZI ２３ →MZI２７ [C] → y ６ .

[0091] In short, the MZI placed on the 6th row ２０ ~MZI ２３ are the input nodes x ４ Light is input from the monitor photodetector MPD ５ ~MPD ７ , output node y ６ The MZIs arranged in the sixth row are monitored by the photodetectors connected to the ２０ ~MZI ２３ In the adjustment of (1), the signal passes through an MZI whose characteristics are known and already adjusted, so that only the characteristics of the MZI to be adjusted can be extracted with high precision.

[0092] In addition, since the light does not pass through the MZI whose state, either through or cross, is unknown, all the light guided through the adjustment waveguide path can be detected, and the light intensity during adjustment can be maximized. This maximizes the signal-to-noise ratio, enabling highly accurate adjustment. １６ ~MZI １９ For convenience, this is the first half, but it could also be the second half, or it could be the middle part between the first half and the Koehan Fusema.

[0093] The optical arithmetic device according to the second embodiment has the same effect as the optical arithmetic device according to the first embodiment, and in addition, since the MZIs in the first half and the MZIs in the second half can be adjusted in parallel for each row in the multi-stage MZI array 1, the adjustment can be completed in a shorter time.

[0094] Third Embodiment An optical arithmetic device according to a third embodiment will be described with reference to Fig. 10. The optical arithmetic device according to the third embodiment is an MZI in which the optical arithmetic device according to the first embodiment is arranged in the first row. ０ ~MZI ３ The corresponding monitor photodetector MPD ０ ~MPD ３ is placed in the first row, while MZI ０ ~MZI ３ A single aggregated MPD for all Ｉ10, the same reference numerals as those in FIGS. 1 to 6 denote the same or corresponding parts.

[0095] Monitor photodetector MPD Ｉ is the MZI placed in the first row ０ , MZI １ , MZI ２ , MZI ３ Each of the first output ports Port3 is an aggregated photodiode having four input terminals, from the 0th input terminal to the 3rd input terminal, connected to the respective first output ports Port3. ０ , MZI １ , MZI ２ , MZI ３ Each of the photodiodes has a pin structure and includes a light absorption layer connected to one end of a waveguide, the other end of which is connected to the first output port Port3.

[0096] The specific procedure of the MZI adjustment method in the optical arithmetic device according to the third embodiment is substantially the same as the specific procedure of the MZI adjustment method in the optical arithmetic device according to the first embodiment. In steps ST1 to ST9, the monitor photodetector MPD0 １ ~MPD ３ The monitoring is performed by a monitoring photodetector MPD. Ｉ The only difference is that monitoring is performed by

[0097] However, in step ST1, in the first embodiment, the MZI arranged in the first row ０ ~MZI ３ The adjustment order for MZI is performed in the order of the indexes, but it is performed in the reverse order of the indexes. ０ ~MZI ３ For each, the monitor input node p corresponding to the reverse order of the index ０ ~p ３ Light is input to the monitor photodetector MPD Ｉ MZI ０ ~MZI ３Adjustments are made to compensate for the variations in the branching ratios of the MZIs. ０ ~MZI ３ Set each one to "through".

[0098] In short, the MZI to be adjusted ３ For input node p ３ and the photodetector is MPD Ｉ The p ３ →MZI ３ →MPD Ｉ The adjustment is performed by the optical waveguide path of MZI. ３ After adjustment, the optical waveguide paths are formed and adjusted in the following order: ２ For p ２ →MZI ２ →MPD Ｉ MZI to be adjusted １ For p １ →MZI １ →MPD Ｉ MZI to be adjusted ０ For p ０ →MZI ０ →MPD Ｉ In step ST1, the MZI arranged in the first row ０ ~MZI ３ The adjustment is complete and the characteristics are known.

[0099] In a multi-stage MZI array 1 in which the number of rows is 2N+1 and the number of columns is 2N, the adjustment order of the MZIs arranged in the first row is the reverse order of the indexes, N-1, N-2, ..., 1, 0, that is, MZI Ｎ－１ , MZI Ｎ－２ , ..., MZI １ , MZI ０ Steps ST2 to ST9 are the same as those in the first embodiment.

[0100] The optical arithmetic device according to the third embodiment has the same effects as the optical arithmetic device according to the first embodiment, and in addition, the optical arithmetic device according to the third embodiment has a monitor photodetector MPD Ｉ Since the circuit elements are integrated as a single circuit, the number of circuit elements can be reduced, and the yield and manufacturing costs can be improved.

[0101] Fourth Embodiment An optical arithmetic device according to a fourth embodiment will be described with reference to FIG. 11. The optical arithmetic device according to the second embodiment has an MZI arranged in the first row. ０ ~MZI ３ Correspondingly, the first monitoring photodetector MPD ０ ~MPD ３ is placed in the bottom row, the 9th row, and the MZI ３２ ~MZI ３５ Correspondingly, a second monitor photodetector MPD ４ ~MPD ７ will be placed.

[0102] In contrast, in the optical arithmetic device according to the fourth embodiment, the MZI arranged in the first row ０ ~MZI ３ A single integrated first monitor photodetector MPD is used for all of the above. Ｉ is placed, and MZI placed on the 9th row ３２ ~MZI ３５ A single common monitor photodetector MPD is used for all of the above. II will be placed.

[0103] The optical arithmetic device according to the fourth embodiment differs from the optical arithmetic device according to the second embodiment in that a first monitor photodetector MPD Ｉ and a second monitoring photodetector MPD. II 10, the same reference numerals as those in FIGS. 1 to 6 denote the same or corresponding parts.

[0104] First monitoring photodetector MPD Ｉ is the MZI placed in the first row ０ , MZI １ , MZI ２ , MZI ３ Each of the first output ports Port3 is an aggregated photodiode having four input terminals, from the 0th input terminal to the 3rd input terminal, connected to the respective first output ports Port3. ０ , MZI １ , MZI ２ , MZI ３Each of the photodiodes has a pin structure and includes a light absorption layer connected to one end of a waveguide, the other end of which is connected to the first output port Port3.

[0105] Second monitor photodetector MPD II is the MZI placed on the 9th line ３２ , MZI ３３ , MZI ３４ , MZI ３５ Each of the first output ports Port3 is an aggregated photodiode having four input terminals, from the 0th input terminal to the 3rd input terminal, connected to the respective first output ports Port3. ３２ , MZI ３３ , MZI ３４ , MZI ３５ Each of the photodiodes has a pin structure and includes a light absorption layer connected to one end of a waveguide, the other end of which is connected to the first output port Port3.

[0106] The specific procedure of the MZI adjustment method in the optical arithmetic device according to the third embodiment is substantially the same as the specific procedure of the MZI adjustment method in the optical arithmetic device according to the second embodiment. In steps ST1 to ST5, the first group of monitor photodetectors MPD ０ ~MPD ３ The first monitoring photodetector MPD Ｉ and the second group of monitoring photodetectors MPD0 ４ ~MPD ７ The second monitoring photodetector MPD II The only difference is that monitoring is performed by

[0107] However, in step ST1, in the first embodiment, the MZI arranged in the first row ０ ~MZI ３ The adjustment order for the MZI placed in the 9th row is in index order. ３２ ~MZI ３５ The adjustment order for is performed in the order of the indexes, but in the first and ninth rows, the adjustment order is reversed.

[0108] That is, in step ST1, MZI ０ ~MZI ３ For each, the monitor input node p corresponding to the reverse order of the index ０ ~p ３ Light is input to the monitor photodetector MPD Ｉ MZI ０ ~MZI ３ Adjustments are made to compensate for the variations in the branching ratios of the MZIs. ３２ ~MZI ３５ For each, the monitor input node p corresponding to the reverse order of the index ４ ~p ７ Light is input to the monitor photodetector MPD II MZI ３２ ~MZI ３５ Adjustments are made to compensate for the variations in the branching ratios of the MZIs. ０ ~MZI ３ and MZI ３２ ~MZI ３５ Set each one to "through".

[0109] In short, the MZI to be adjusted ３ For the monitor input node p ３ and the photodetector is MPD Ｉ The p ３ →MZI ３ →MPD Ｉ At the same time, the adjustment target MZI ３５ For the monitor input node p ７ and the photodetector is MPD II The p ７ →MZI ３５ →MPD II The adjustment is performed by the optical waveguide path of MZI. ３ and MZI ３５ is set to through state after adjustment.

[0110] The optical waveguide paths are formed and adjusted in the following order: ２ For p ２ →MZI ２ →MPD Ｉ and the MZI to be adjusted is３４ For p ６ →MZI ３４ →MPD II Adjustment target MZI １ For p １ →MZI １ →MPD Ｉ and the MZI to be adjusted is ３３ For p ５ →MZI ３３ →MPD II Let's say.

[0111] MZI to be adjusted ０ For p ０ →MZI ０ →MPD Ｉ and the MZI to be adjusted is ３２ For p ４ →MZI ３２ →MPD II In step ST1, the MZI arranged in the first row ０ ~MZI ３ and MZI placed on the 9th line ３２ ~MZI ３５ The adjustment is complete and the characteristics are known.

[0112] In a multi-stage MZI array 1 in which the number of rows is 2N+1 and the number of columns is 2N, the adjustment order of the MZIs arranged in the first row is the reverse order of the indexes, N-1, N-2, ..., 1, 0, that is, MZI Ｎ－１ , MZI Ｎ－２ , ..., MZI １ , MZI ０ In addition, the adjustment order of the MZIs arranged in the bottom row (2N+1) is the reverse order of the index, that is, in descending order of the number of columns, that is, (2N+1)N-1, (2N+1)N-2, ..., (2N+1)N-N, that is, MZI （２Ｎ＋１）Ｎ－１ , MZI （２Ｎ＋１）Ｎ－２ , ..., MZI （２Ｎ＋１）Ｎ－Ｎ Steps ST2 to ST5 are the same as those in the second embodiment.

[0113] The optical arithmetic device according to the fourth embodiment has the same effects as the optical arithmetic device according to the second embodiment, and in addition, the first monitoring photodetector MPD Ｉand a second monitoring photodetector MPD. II Since the circuit elements are integrated as a single circuit, the number of circuit elements can be reduced, and the yield and manufacturing costs can be improved.

[0114] In the fourth embodiment, the MZI arranged in the first row ０ ~MZI ３ A single integrated first monitor photodetector MPD is commonly arranged for all of the above. Ｉ Instead, as shown in the optical arithmetic device according to the second embodiment, the MZI arranged in the first row ０ ~MZI ３ Correspondingly, the first monitoring photodetector MPD ０ ~MPD ３ That is, the MZI arranged in the first row may be ０ ~MZI ３ Correspondingly, the first monitoring photodetector MPD ０ ~MPD ３ is placed, and MZI placed on the 9th row ３２ ~MZI ３５ A single common monitor photodetector MPD is used for all of the above. II may be arranged.

[0115] In the fourth embodiment, the MZI arranged in the ninth row ３２ ~MZI ３５ A single common integrated second monitor photodetector MPD is provided for all of the above. II Instead, as shown in the optical arithmetic device according to the second embodiment, the MZI arranged in the 9th row ３２ ~MZI ３５ Correspondingly, a second monitor photodetector MPD ４ ~MPD ７ may be arranged.

[0116] That is, the MZI arranged in the first row ０ ~MZI ３ A single integrated first monitor photodetector MPD is used for all of the above. Ｉ is placed, and MZI placed on the 9th row ３２ ~MZI ３５Correspondingly, a second monitor photodetector MPD ４ ~MPD ７ may be arranged.

[0117] It should be noted that the embodiments may be freely combined, or any of the components in each embodiment may be modified, or any of the components in each embodiment may be omitted.

[0118] The optical computing device according to the present disclosure is applicable to applications using analog computing techniques such as machine learning and quantum computing.

[0119] 1 Multi-stage MZI array, MZI ０ From MZI ３５ Mach-Zehnder interferometer, MPD ０ ~MPD ３ , M.P.D. Ｉ (First) Monitor Photodetector, MPD ４ ~MPD ７ , M.P.D. II a second monitor photodetector, x ０ ~x ７ input node, y ０ ~y ７ Output node.

Claims

1. An optical computing device comprising: a multi-stage MZI array in which Mach-Zehnder interferometers arranged in odd-numbered columns are arranged in even-numbered rows and Mach-Zehnder interferometers arranged in even-numbered columns are arranged in odd-numbered rows in a matrix of multiple rows and multiple columns, and the Mach-Zehnder interferometers arranged in the even-numbered columns are arranged in odd-numbered rows; and a monitor photodetector connected to the first output port of the Mach-Zehnder interferometer arranged in the first row.

2. The optical computing device according to claim 1, wherein in the multistage MZI array, where the number of Mach-Zehnder interferometers arranged in the first column is N (N is a natural number of 2 or more), the number of rows is 2N+1 and the number of columns is 2N, the index of the Mach-Zehnder interferometer in the first row and second column is set to 0, the indices of the Mach-Zehnder interferometers arranged in the first row are increased by 1 in order of the columns, the Mach-Zehnder interferometer in the second row and first column is placed after the Mach-Zehnder interferometer in the first row and Nth column, the indices of the Mach-Zehnder interferometers arranged in the second row are increased by 1 in order of the columns, and indices are similarly assigned in order up to [N×(2N+1)-1] up to the Mach-Zehnder interferometer in the 2N+1 row and Nth column.

3. An optical computing device according to claim 1 or 2, wherein the monitoring photodetectors are arranged corresponding to the Mach-Zehnder interferometers arranged in the first row.

4. An optical computing device according to claim 1 or 2, wherein the monitoring photodetector is arranged in common for all of the Mach-Zehnder interferometers arranged in the first row.

5. An optical computing device according to any one of claims 1 to 4, further comprising a second monitor photodetector connected to a second output port of the Mach-Zehnder interferometer arranged in the bottom row.

6. The optical computing device according to claim 5, wherein said second monitoring photodetectors are arranged corresponding to the Mach-Zehnder interferometers arranged in the bottom row.

7. The optical computing device according to claim 5, wherein said second monitoring photodetector is arranged in common for all of the Mach-Zehnder interferometers arranged in the bottom row.

8. A method for adjusting a Mach-Zehnder interferometer in an optical computing device comprising: a multi-stage MZI array in which Mach-Zehnder interferometers arranged in odd-numbered columns are arranged in even-numbered rows in a matrix of multiple rows and multiple columns, the Mach-Zehnder interferometers arranged in even-numbered columns being arranged in odd-numbered rows, and a monitor photodetector connected to a first output port of the Mach-Zehnder interferometer arranged in the first row, wherein, with respect to the Mach-Zehnder interferometer to be adjusted to compensate for branching ratio variations, the Mach-Zehnder interferometer arranged in the front row in an optical waveguide path through which light passes through the Mach-Zehnder interferometer to be adjusted is set to a through state, and the Mach-Zehnder interferometer arranged in the rear row in the optical waveguide path is set to a cross state, and adjustment is made to compensate for branching ratio variations in the Mach-Zehnder interferometer to be investigated.

9. A method for adjusting a Mach-Zehnder interferometer in an optical computing device as set forth in claim 8, wherein an optical signal is input to the first input port of a Mach-Zehnder interferometer to be adjusted and the optical signal is output to the monitor photodetector connected to the first output port of the Mach-Zehnder interferometer, and an optical signal is output to the monitor photodetector connected to the first output port of the Mach-Zehnder interferometer, and a method for adjusting a Mach-Zehnder interferometer to be adjusted in a second or subsequent row is performed by using only the inspected Mach-Zehnder interferometer as the optical waveguide path.

10. A method for adjusting a Mach-Zehnder interferometer in an optical computing device as set forth in claim 8 or claim 9, wherein the monitor photodetectors are arranged corresponding to the Mach-Zehnder interferometers arranged in the first row, and the Mach-Zehnder interferometers arranged in the first row are adjusted in ascending order of the number of columns in which they are arranged by inputting an optical signal to their first input port and outputting an optical signal to their corresponding monitor photodetector connected to their first output port.

11. A method for adjusting a Mach-Zehnder interferometer in an optical computing device according to claim 8 or claim 9, wherein the monitor photodetector is arranged in common for all Mach-Zehnder interferometers arranged in the first row, and the Mach-Zehnder interferometers arranged in the first row are adjusted in descending order of the number of columns in which they are arranged by inputting an optical signal to their first input port and outputting an optical signal to a common monitor photodetector connected to their first output port.

12. A multi-stage MZI array is provided in which, in a matrix with multiple rows and multiple columns, Mach-Zehnder interferometers arranged in odd-numbered columns are arranged in even-numbered rows, and Mach-Zehnder interferometers arranged in even-numbered columns are arranged in odd-numbered rows, and the Mach-Zehnder interferometers are arranged in a rectangular shape; and a monitor photodetector is connected to a first output port of the Mach-Zehnder interferometer arranged in the first row, and in the multi-stage MZI array, when the number of Mach-Zehnder interferometers arranged in the first column is N (N is a natural number of 2 or more), the number of rows is 2N+1 and the number of columns is 2N, and the index of the Mach-Zehnder interferometer in the first row and second column is 0. and the index of the Mach-Zehnder interferometer arranged in the first row is increased by one in the order of the columns, so that the Mach-Zehnder interferometer in the second row and first column is placed after the Mach-Zehnder interferometer in the first row and Nth column, and the index of the Mach-Zehnder interferometer arranged in the second row is increased by one in the order of the columns, and similarly, the indexes [N×(2N+1)−1] are assigned up to the Mach-Zehnder interferometer in the (2N+1)th row and Nth column, and adjustments to compensate for branching ratio variations in the Mach-Zehnder interferometers are performed in the order of the indexes from 0 to [N×(2N+1)−1].

13. A method for adjusting a Mach-Zehnder interferometer in an optical computing device comprising: a multi-stage MZI array in which Mach-Zehnder interferometers arranged in odd-numbered columns are arranged in even-numbered rows and Mach-Zehnder interferometers arranged in even-numbered columns are arranged in odd-numbered rows in a matrix of multiple rows and multiple columns, the Mach-Zehnder interferometers being arranged in a rectangular shape; a first monitor photodetector connected to a first output port of the Mach-Zehnder interferometer arranged in the first row; and a second monitor photodetector connected to a second output port of the Mach-Zehnder interferometer arranged in the bottom row, the method comprising: The Mach-Zehnder interferometer arranged in the first row to be adjusted to compensate for branching ratio variations has an optical signal input to its first input port and outputs an optical signal to the first monitor photodetector connected to its first output port, and is adjusted; simultaneously, the Mach-Zehnder interferometer arranged in the bottom row to be adjusted to compensate for branching ratio variations has an optical signal input to its second input port and outputs an optical signal to the second monitor photodetector connected to its second output port, and is adjusted; the multiple rows are divided into a first half and a second half, and adjustments are made to compensate for branching ratio variations for the Mach-Zehnder interferometers arranged in the first half rows and the Mach-Zehnder interferometers arranged in the second half rows, sequentially from the second row in the first half to the bottom row in the first half, and from the bottom row to the previous row to the top row in the second half, and ... and are adjusted to compensate for branching ratio variations for the Mach-Zehnder interferometers arranged in each row, with only the investigated Mach-Zehnder interferometer being used as the optical waveguide path. A method for adjusting a Mach-Zehnder interferometer in an optical computing device.

14. A method for adjusting a Mach-Zehnder interferometer in an optical computing device as set forth in claim 13, wherein: the first monitor photodetector is arranged corresponding to each Mach-Zehnder interferometer arranged in the first row; the second monitor photodetector is arranged corresponding to each Mach-Zehnder interferometer arranged in the bottom row; the Mach-Zehnder interferometers arranged in the first row are adjusted in ascending order of the number of columns in which they are arranged by inputting an optical signal to their first input port and outputting an optical signal to their corresponding first monitor photodetector connected to their first output port; and the Mach-Zehnder interferometers arranged in the bottom row are adjusted in ascending order of the number of columns in which they are arranged by inputting an optical signal to their first input port and outputting an optical signal to their corresponding second monitor photodetector connected to their first output port.

15. A method for adjusting a Mach-Zehnder interferometer in an optical computing device as set forth in claim 13, wherein: the first monitor photodetector is arranged in common for all Mach-Zehnder interferometers arranged in the first row; the second monitor photodetector is arranged in common for all Mach-Zehnder interferometers arranged in the bottom row; the Mach-Zehnder interferometers arranged in the first row are adjusted in descending order of the number of columns in which they are arranged by inputting an optical signal to their first input port and outputting the optical signal to a common first monitor photodetector connected to their first output port; and the Mach-Zehnder interferometers arranged in the bottom row are adjusted in descending order of the number of columns in which they are arranged by inputting an optical signal to their first input port and outputting the optical signal to a common second monitor photodetector connected to their first output port.

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