CN116822601A - A matrix operation accelerator combining wavelength division multiplexing and MZI cascade network - Google Patents

Abstract

The application provides a matrix operation accelerator combining wavelength division multiplexing and MZI cascade network, which relates to the field of optical neural network, and comprises the following components: an input signal layer for realizing matrix operation of the optical signals through the Mach-Zehnder interferometer array; a weight signal layer for applying an electrical signal to the micro-ring modulator array to adjust the weight signal; the summing layer is used for separating the action results of the weight signals of the optical signals with different wavelengths; and the nonlinear layer is used for converting the optical signals into electric signals through the photoelectric detector array and realizing nonlinear activation functions in an electric domain. According to the application, the number of times of matrix operation execution is increased by N times each time by introducing N different wavelengths into a network formed by MZI cascade connection, which is favorable for executing high-speed convolution operation, and the energy efficiency and the area ratio of MZI cascade network calculation can be effectively increased due to the relatively smaller size of the micro-ring modulator.

Description

A matrix operation accelerator combining wavelength division multiplexing and MZI cascade network

Technical field

This application relates to the field of optical neural networks, and in particular to a matrix operation accelerator that combines wavelength division multiplexing and MZI cascade networks.

Background technique

With the rapid development of information technology, massive amounts of data and information are constantly being generated, which provides a good foundation for the rapid development of neural networks. Therefore, neural networks have made considerable achievements in computer vision, natural language processing, and medical imaging. However, the processing and calculation of these massive amounts of information place higher requirements on hardware performance, requiring higher computing speed and lower power consumption. However, as the characteristic size of transistors gradually approaches the physical limit and enters the nanometer level, the development of integrated circuits has also encountered a bottleneck, making it difficult to continue Moore's Law.

Since photonic devices have higher bandwidth and lower energy consumption than electronic devices, photonic devices are also being used to implement matrix operations in neural networks. The current implementation of optical neural networks mainly includes cascaded Mach-Zehnder arrays and micro-ring modulator arrays.

However, the number of devices required to implement matrix operations based on Mach-Zehnder interferometers is squarely related to the dimensions of the matrix, and the size of the devices is also large, so it is difficult to implement large-scale matrix operations. When implementing non-square matrix operations, that is, when the number of rows of the matrix is not equal to the number of columns, there will be redundant Mach-Zehnder interferometers, which reduces the efficiency of performing effective matrix operations.

Contents of the invention

In response to the above problems, a matrix operation accelerator combining wavelength division multiplexing and MZI cascade network is proposed, including:

The input signal layer is used to implement matrix operations of optical signals through the Mach-Zehnder interferometer array;

The weight signal layer is used to apply electrical signals to the microring modulator array to adjust the weight signal;

A summation layer, used to separate the optical signals of different wavelengths through the action results of the weighting signal;

The nonlinear layer is used to convert the optical signal into an electrical signal through the photodetector array, and implement a nonlinear activation function in the electrical domain.

Optionally, the input signal layer includes:

Semiconductor laser, used to emit the optical signals of different wavelengths;

A wavelength division multiplexing device for multiplexing the optical signals of different wavelengths in the same waveguide;

A multi-mode interferometer module, configured to evenly distribute the optical signal to each input port of the Mach-Zehnder interferometer array according to power;

The Mach-Zehnder interferometer array realizes the matrix operation of the multiplexed optical signal.

Optionally, the semiconductor laser includes:

Distributed feedback semiconductor laser;

Distributed Bragg reflection semiconductor laser;

Vertical cavity surface emitting laser.

Optionally, the wavelength division multiplexing device is an arrayed waveguide grating or a cascaded Mach-Zehnder interferometer type multiplexer.

Optionally, the multi-mode interferometer module is a 1×N multi-mode interferometer or is composed of a cascade of log ₂ N 1×2 multi-mode interferometers.

Optionally, the Mach-Zehnder interferometer array includes unitary matrix array 1, diagonal matrix array 2 and unitary matrix array 3, where,

The unitary matrix array 1 includes a cascade of N(N-1)/2 first Mach-Zehnder interferometer arrays;

The diagonal matrix array 2 includes a cascade of N second Mach-Zehnder interferometer arrays;

The unitary matrix array 3 includes a cascade of N(N-1)/2 third Mach-Zehnder interferometer arrays;

Among them, N is the dimension of the matrix to be operated.

Optionally, the unitary matrix array 1, diagonal matrix array 2 and unitary matrix array 3 are composed of multiple identical Mach-Zehnder interferometers, wherein,

The Mach-Zehnder interferometer includes a coupler module and a phase shifter module;

The coupler module is composed of a multi-mode interferometer or a directional coupler, and the phase shifter module implements functions based on thermo-optical effects or electro-optical effects.

Optionally, the weighted signal layer includes the micro-ring modulator array and the crossed waveguide array, wherein,

The microring modulator array includes a plurality of microring modulators, and the crossed waveguide array includes a plurality of crossed waveguides;

The micro-ring modulator and the cross waveguide form a plurality of basic components, wherein the optical signal is input from the in1 or in2 port of the basic component unit, and the optical signal is adjusted by adjusting the micro-ring modulator. Output along the out1 or out2 port.

Optionally, the photodetector array includes:

a first sub-array of photodetectors, used to calibrate the resonant wavelength of each of the micro-ring modulators;

The second sub-array of photodetectors is used to detect the power value of each output port and implement a nonlinear activation function in the electrical domain.

The technical solutions provided by the embodiments of the present application at least bring the following beneficial effects:

By introducing N different wavelengths into the network formed by the MZI cascade, the number of matrix operations performed each time is expanded by N times, which is conducive to performing high-speed convolution operations, and due to the relatively small size of the microring modulator, It can effectively increase the energy efficiency and area ratio of MZI cascade network computing.

Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application.

Description of the drawings

The above and/or additional aspects and advantages of the present application will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

Figure 1 is a structural diagram of a matrix operation accelerator that combines wavelength division multiplexing and MZI cascade networks according to an embodiment of the present application;

Figure 2 is a structural diagram of a Mach-Zehnder interferometer according to an embodiment of the present application;

Figure 3 is a structural diagram of a basic component unit according to an embodiment of the present application.

Detailed ways

The embodiments of the present application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present application, but should not be construed as limiting the present application.

Figure 1 is a structural diagram of a matrix operation accelerator that combines wavelength division multiplexing and MZI cascade networks according to an embodiment of the present application, including:

The input signal layer is used to implement matrix operations of optical signals through the Mach-Zehnder interferometer array;

The weight signal layer is used to apply electrical signals to the microring modulator array to adjust the weight signal;

The summation layer is used to separate the effects of weighted signals on optical signals of different wavelengths;

The nonlinear layer is used to convert optical signals into electrical signals through the photodetector array and implement nonlinear activation functions in the electrical domain.

The structure and function of each component are introduced in detail below.

As shown in Figure 1, the input signal layer includes semiconductor lasers LD1-LD3, wavelength division multiplexing device Demux1, multi-mode interferometer module MMI and Mach-Zehnder interferometer array MZI1-MZI9.

Specifically, LD1-LD3 are three semiconductor lasers with different emission wavelengths. The semiconductor lasers include distributed feedback semiconductor lasers, distributed Bragg reflection semiconductor lasers and vertical cavity surface emitting lasers.

In a possible embodiment, LD1 is a distributed Bragg reflection semiconductor laser.

Among them, Demux1 is a wavelength division multiplexing device that multiplexes optical signals of different wavelengths in the same waveguide. The wavelength division multiplexing device includes an arrayed waveguide grating or a cascaded Mach-Zehnder interferometer type multiplexer.

In a possible embodiment, Demux1 is an arrayed waveguide grating.

MMI uses its wavelength insensitivity feature to evenly distribute the combined optical signals to each output port according to power. The multimode interferometer module is a 1×N multimode interferometer or consists of log ₂ N 1×2 multimode interferences. Instrument cascade composition.

In a possible embodiment, the MMI is a 1×N multi-mode interferometer.

In addition, the Mach-Zehnder interferometer array includes unitary matrix array 1, diagonal matrix array 2 and unitary matrix array 3, where,

The unitary matrix array 1 includes a cascade of N(N-1)/2 first Mach-Zehnder interferometer arrays;

The diagonal matrix array 2 includes a cascade of N second Mach-Zehnder interferometer arrays;

The unitary matrix array 3 includes a cascaded N(N-1)/2 third Mach-Zehnder interferometer array;

Among them, N is the dimension of the matrix to be operated.

As shown in Figure 2, MZI1-MZI9 are Mach-Zehnder interferometers, used to implement arbitrary matrix operations. Among them, MZI1-MZI3 are unitary matrix array 1, MZI4-MZI6 are diagonal matrix array 2, and MZI7-MZI9 are unitary matrix arrays. Matrix array 3, MZI1-MZI3 realize the function of unitary matrix 1, MZI4-MZI6 realize the function of diagonal matrix 2, MZI7-MZI9 realize the function of unitary matrix 3.

Among them, MZI4-MZI6 can be realized by using an adjustable optical attenuator in addition to using a Mach-Zehnder interferometer.

In the embodiment of this application, each MZI is composed of multiple identical Mach-Zehnder interferometers, as shown in Figure 2. Its components include two 2×2 couplers, coupler1 and coupler2, and two ps1 and ps2. Phase shifters and couplers are implemented by multi-mode interferometers or directional couplers, and phase shifters are implemented by thermo-optical effects or electro-optical effects.

As shown in Figure 1, MRM1-MRM9 are micro-ring modulator arrays, and Cross1-Cross9 are crossed waveguide arrays. The basic components of the micro-ring modulator and cross waveguide are shown in Figure 3. The optical signal is transmitted through the in1 or in2 port. Input, by adjusting the signal of the microring modulator, the optical signal is output along the out1 and out2 ports.

Among them, in the N×N micro-ring modulator array, the resonant wavelengths of the micro-ring modulators in each column are the same, and the resonant wavelengths from the first column to the N-th column are λ ₁ , λ ₂ ...λ _N respectively.

As shown in Figure 1, PD1-PD6 are photodetector arrays, in which PD1-PD3 are the first sub-array of photodetectors, used to calibrate the resonant wavelength of each micro-ring modulator, and PD4-PD6 are the first sub-arrays of photodetectors. Two sub-arrays are used to detect the power value of each output port and implement a nonlinear activation function in the electrical domain.

The embodiment of the present application expands the number of matrix operations by N times by introducing N different wavelengths into the network formed by the MZI cascade, which is conducive to performing high-speed convolution operations, and due to the size of the micro-ring modulator Relatively small, it can effectively increase the energy efficiency and area ratio of MZI cascade network computing.

It should be understood that various forms of the process shown above may be used, with steps reordered, added or deleted. For example, each step described in the present disclosure can be executed in parallel, sequentially, or in a different order. As long as the desired results of the technical solution disclosed in the present disclosure can be achieved, there is no limitation here.

The above-mentioned specific embodiments do not constitute a limitation on the scope of the present disclosure. It will be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions are possible depending on design requirements and other factors. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this disclosure shall be included in the protection scope of this disclosure.

Claims (9)

1. A matrix operation accelerator combining wavelength division multiplexing and MZI cascade networks, comprising:

an input signal layer for realizing matrix operation of the optical signals through the Mach-Zehnder interferometer array;

a weight signal layer for applying an electrical signal to the micro-ring modulator array to adjust the weight signal;

a summation layer for separating the effect results of the optical signals with different wavelengths passing through the weight signals;

and the nonlinear layer is used for converting the optical signals into electric signals through the photoelectric detector array and realizing nonlinear activation functions in an electric domain.

2. The matrix operation accelerator combining wavelength division multiplexing and MZI cascade network of claim 1, wherein said input signal layer comprises:

a semiconductor laser for emitting the optical signals of different wavelengths;

the wavelength division multiplexing device is used for multiplexing the optical signals with different wavelengths in the same waveguide;

the multimode interferometer module is used for distributing the optical signals to each input port of the Mach-Zehnder interferometer array according to power average;

and the Mach-Zehnder interferometer array is used for realizing matrix operation of the combined wave optical signals.

3. The matrix operation accelerator combining wavelength division multiplexing and MZI cascade network of claim 2, wherein said semiconductor laser comprises:

a distributed feedback semiconductor laser;

a distributed Bragg reflection semiconductor laser;

vertical cavity surface emitting lasers.

4. The matrix operation accelerator combining wavelength division multiplexing and MZI cascade network of claim 2, wherein said wavelength division multiplexing device is an arrayed waveguide grating or a cascaded mach-zehnder interferometer multiplexer.

5. The matrix operation accelerator combining wavelength division multiplexing and MZI cascade network of claim 2, wherein the multimode interferometer module is a 1 x N multimode interferometer or is composed of logs ₂ N1 x 2 multimode interferometer cascades.

6. The matrix operation accelerator combining wavelength division multiplexing and MZI cascade network according to claim 2, wherein the Mach-Zehnder interferometer array comprises a unitary matrix array 1, a diagonal matrix array 2, and a unitary matrix array 3, wherein,

the unitary matrix array 1 comprises a cascade of N (N-1)/2 first Mach-Zehnder interferometer arrays;

the diagonal matrix array 2 comprises N cascaded second Mach-Zehnder interferometer arrays;

the unitary matrix array 3 comprises a cascaded N (N-1)/2 third Mach-Zehnder interferometer arrays;

where N is the dimension of the matrix to be operated on.

7. The matrix operation accelerator combining wavelength division multiplexing and MZI cascade network according to claim 6, wherein the unitary matrix array 1, the diagonal matrix array 2 and the unitary matrix array 3 are composed of a plurality of identical Mach-Zehnder interferometers, wherein,

the Mach-Zehnder interferometer comprises a coupler module and a phase shifter module;

the coupler module is composed of a multimode interferometer or a directional coupler, and the phase shifter module realizes functions according to a thermo-optical effect or an electro-optical effect.

8. The matrix operation accelerator combining wavelength division multiplexing and MZI cascade network according to claim 7, wherein said weight signal layer comprises said micro-ring modulator array and cross waveguide array, wherein,

the micro-ring modulator array comprises a plurality of micro-ring modulators, and the cross waveguide array comprises a plurality of cross waveguides;

the micro-ring modulator and the cross waveguide form a plurality of basic constituent units, wherein the optical signals are input by an in1 or in2 port of the basic constituent units, and the optical signals are output along an out1 or out2 port by adjusting the micro-ring modulator.

9. The matrix operation accelerator combining wavelength division multiplexing and MZI cascade network of any of claims 1 or 8, wherein said photodetector array comprises:

a first sub-array of photodetectors for calibrating a resonant wavelength of each of the micro-ring modulators;

and the second subarray of the photoelectric detector is used for detecting the power value of each output port and realizing a nonlinear activation function in an electric domain.