Reconfigurable optical matrix-vector multiplication structure and method based on free spectral range of micro-ring resonator

Abstract

The invention provides a structure and a method for reconfigurable calculation of an optical matrix vector multiplication based on a free spectral range. Examples of structures and methods disclosed herein include encoding a weight matrix into a plurality of optical signals based on a plurality of free spectral ranges (FSRs) of a resonator structure. The resonator structure has resonance tuned based on a weight matrix. An optical signal may be input into an input waveguide optically coupled with the resonator structure array. The waveguide is provided with a plurality of phase-change materials for storing information of different input vectors, and all the phase-change materials jointly realize a reconfigurable function. A result representing the weight matrix multiplied by the input vector may be generated based on the optical power output from the resonator structure array.

Description

Technical Field

[0001] The invention relates to a structure and method of reconfigurable optical matrix-vector multiplication based on the free spectral range of a micro-ring resonator, and belongs to the field of photon computing. Background Art

[0002] Matrix-Vector Multiplications (MVM) operation is one of the basic mathematical operations widely used in large-scale neuromorphic optoelectronic computing.

[0003] Photonic computing structures have the characteristics of high speed and parallelism, and have outstanding advantages in processing linear calculations, becoming a hot topic in current international research. People use new optical materials such as optical waveguide micro-nano structures and microlens arrays to build photonic computing chips and apply them to different scenarios.

[0004] With the advent of the era of artificial intelligence and big data, the demand for high computing performance and small size photonic chips is increasing. For example, due to the need for complex artificial intelligence inference calculations, this will lead to a doubling of the number of optical devices in the computing array. In order to achieve good performance, at least tens of thousands of optical devices are required, which will also lead to more complex structures and larger sizes. In order to achieve programmability, this will require chips with higher integration.

[0005] In this context, photonic computing hardware has become an effective way to break through the bottleneck of electronic technology. The biggest feature of photonic computing hardware is zero energy consumption for data transmission and ultra-high clock speed, which ensures that photonic computing hardware has the potential to break through the highest level of existing electronic technology when performing matrix multiplication. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention proposes a structure and method of reconfigurable optical matrix-vector multiplication based on the free spectral range of a microring resonator.

[0007] In order to achieve the above technical purpose, the technical solution adopted by the present invention is:

[0008] On the one hand, the present invention provides an optical matrix vector multiplication structure and method, including a micro-ring resonator and a phase change material GST, wherein the GST is arranged on a waveguide.

[0009] Furthermore, in the optical matrix vector multiplication structure and method, the radius of the microring resonator depends on the wavelength of the optical signal to be screened, and each row element of the weight matrix is ​​separated by the microring resonator.

[0010] Furthermore, in the optical matrix vector multiplication structure and method, the transmittance of the GST represents the input vector, the GSTs used for reconstruction are connected in parallel with each other, and only one GST is selected for operation in one optical matrix vector calculation.

[0011] Furthermore, in the optical matrix vector multiplication structure and method, the crystallinity of the GST can be preset. Specifically, the crystallinity of the GST is adjusted by heating or cooling. The transmittance of the GST to the optical signal is different under different crystallinity, and the input vector is represented by the transmittance of the GST.

[0012] Furthermore, the optical matrix-vector multiplication structure and method are N output results of multiplying an N×N weight matrix with an N×1 input vector, having N(N+1) optical microring resonator units, 2N phase change materials (excluding the number of phase change materials used for reconstruction), and N output waveguides as the result of the operation, N≥2.

[0013] Furthermore, the optical matrix vector multiplication structure and method can use M phase change material GSTs in parallel to realize the reconfigurable function for the phase change material GST corresponding to any element of the input vector. The number M of phase change material GSTs used for reconstruction depends on the specific reconstruction needs.

[0014] The technical advantages of the present invention are: a method for optical matrix vector multiplication calculation implemented by multiple microring resonators and GST, which effectively improves data parallelism by resonating the optical signal at multiple wavelengths through the FSR of the microring resonator; and an all-optical structure is used to implement optical matrix vector multiplication calculation, which has lower power consumption than traditional methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0016] Figure 1 Schematic diagram of the structure of 2X2 optical matrix-vector multiplication in one embodiment of the present invention.

[0017] Figure 2 It is a structural diagram of realizing the reconfigurable function of 2X2 optical matrix vector multiplication in one embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention more clearly understood, the following will be used to clearly illustrate the spirit of the content disclosed by the present invention with the accompanying drawings and detailed descriptions. After understanding the embodiments of the content of the present invention, any person skilled in the art can change and modify the technology taught by the content of the present invention without departing from the spirit and scope of the content of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0019] The optical matrix-vector multiplication computing network is N output results of multiplying an N×N weight matrix with an N×1 input vector, having N(N+1) microring resonator units, 2N phase change materials (excluding the number of phase change materials used for reconstruction), and N output waveguides as the result of the operation, N≥2.

[0020] Reference Figure 1 , an embodiment provides a structure for 2×2 optical matrix vector multiplication calculation, which has a 2X2 weight matrix, a 2X1 input vector and two output ports. Specifically, the structure of the 2X2 optical matrix vector multiplication includes a first microring resonator λ1, a second microring resonator λ2, a third microring resonator λ11, a fourth microring resonator λ12, a fifth microring resonator λ21, and a sixth microring resonator λ22. The first waveguides of the first and second microring resonators serve as the input end of the weight matrix, and the second and third waveguides are respectively located below the first and second microring resonators, and the optical signals are respectively coupled with the third and fourth microring resonators and the fifth and sixth microring resonators. A total of two groups of the first phase change material X1 and the second phase change material X2 carrying the input vector information are respectively located on the fourth and fifth waveguides below the third and fourth microring resonators and the fifth and sixth microring resonators, and the fourth and fifth waveguides are respectively used as two output ports of the 2×2 optical matrix vector multiplication.

[0021] The first microring resonator resonates only with the wavelengths of the optical signals corresponding to W11 and W12 by setting FSR, and the second microring resonator resonates only with the wavelengths of the optical signals corresponding to W21 and W22 by setting FSR, thereby achieving the first screening of the weight matrix optical signal.

[0022] The third microring resonator resonates only with the wavelength of the optical signal corresponding to W11 by setting FSR, the fourth microring resonator resonates only with the wavelength of the optical signal corresponding to W12 by setting FSR, the fifth microring resonator resonates only with the wavelength of the optical signal corresponding to W21 by setting FSR, and the sixth microring resonator resonates only with the wavelength of the optical signal corresponding to W22 by setting FSR, thereby realizing the second screening of the weight matrix optical signal to separate the elements.

[0023] The separated optical signal W11 passes through the first phase change material X1 in the first group, and the intensity of the optical signal changes to W11X1 after passing through the phase change material; the separated optical signal W12 passes through the second phase change material X2 in the first group, and the intensity of the optical signal changes to W12X2 after passing through the phase change material; the separated optical signal W21 passes through the first phase change material X1 in the second group, and the intensity of the optical signal changes to W21X1 after passing through the phase change material; the separated optical signal W22 passes through the second phase change material X2 in the second group, and the intensity of the optical signal changes to W22X2 after passing through the phase change material.

[0024] The optical signals W11X1 and W12X2 are combined and outputted via the fourth waveguide, and the result is W11X1+W12X2; the optical signals W21X1 and W22X2 are combined and outputted via the fifth waveguide, and the result is W21X1+W22X2.

[0025] The above embodiment of the present invention can construct an NxN optical matrix-vector multiplication calculation of any NxN weight matrix and an Nx1 input vector by adding multiple microring resonators and phase change materials.

[0026] Reference Figure 2 An embodiment provides a reconfigurable function of 2×2 optical matrix vector multiplication. Taking the first output waveguide structure of 2X2 optical matrix vector multiplication as an example, specifically, it includes a first microring resonator λ11, a second microring resonator λ12, a first group of M phase change materials carrying input vector information, from X11 to X1m, and a second group of M phase change materials, from X21 to X2m, which are respectively located on the output waveguides below the first and second microring resonators.

[0027] The first microring resonator resonates only with the wavelength of the optical signal corresponding to W11 by setting the FSR, and the second microring resonator resonates only with the wavelength of the optical signal corresponding to W12 by setting the FSR.

[0028] The phase change materials participating in the optical matrix vector multiplication are set according to actual needs. Specifically, taking the setting of the phase change materials GST as X11 and X21 as an example, the GST corresponding to X11 and X21 is set to the required crystallinity, and the remaining phase change materials not participating in the calculation are set to the crystalline state. The optical signal W11 passes through the first phase change material X1 in the first group, and the intensity of the optical signal is changed to W11X1 after passing through the phase change material; the optical signal W12 passes through the second phase change material X2 in the first group, and the intensity of the optical signal is changed to W12X2 after passing through the phase change material.

[0029] The optical signals W11X1 and W12X2 are combined and output through the output waveguide, and the result is W11X1+W12X2.

[0030] The phase change material involved in the optical matrix-vector multiplication can be arbitrarily selected to realize the multiplication of the weight matrix and multiple different input vectors, thereby realizing the reconfigurable function of the optical matrix-vector multiplication calculation.

[0031] Matters not covered by the present invention are known technologies.

[0032] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0033] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A structure and method for reconfigurable optical matrix-vector multiplication based on the free spectral range of a microring resonator, characterized in that: The structure is used to calculate N output results of multiplying an N×N weight matrix with an N×1 input vector, and the structure includes N(N+1) microring resonator units, 2N phase change materials (excluding the number of phase change materials used for reconstruction), and N output waveguides as results of the operation, N≥2.

2. The method according to claim 1, characterized in that: The elements of the weight matrix are tuned by microring resonators, and each element of the input vector is represented by a phase change material.

3. The method according to claim 1, characterized in that The free spectral range (FSR) of the microring resonator is changed by setting its radius, so that each row element of the weight matrix is ​​screened into different output waveguides.

4. The method according to claim 1, characterized in that: The phase change material is germanium antimony tellurium alloy (GST).

5. The method according to claim 1, characterized in that screening the weight matrix to a plurality of optical signals based on a plurality of free spectral ranges (FSRs) of a resonator structure having resonances tuned based on the weight matrix; Inputting the plurality of optical signals into a waveguide having an input vector optically coupled to the resonator structure array to implement multiplication of a weight matrix and the input vector; and generating a matrix-vector multiplication result based on the optical power output from the array of resonator structures.

6. The method according to claim 1, further comprising: The output optical signal is coupled to the resonator structure, wherein the FSR optical signals corresponding to all elements of each row of the weight matrix are filtered into the multiple output waveguides respectively; each element of each row of the weight matrix is ​​then coupled into the multiple output waveguides respectively by the resonator; the optical signal corresponding to each element of the weight matrix passes through the phase change material provided on the output waveguide, wherein the phase change material represents a single element of the configurable input vector, and the final output of the output waveguide can be represented as the result of multiplying the single row element of the weight matrix with the input vector. Finally, the optical power output from each of the multiple output waveguides is detected, wherein each element of the result obtained by the matrix-vector multiplication is generated by the detected optical power from each of the multiple output waveguides.

7. The method according to claim 1, further comprising: By configuring multiple phase change materials in a crystalline or amorphous state, the switching control of the optical signal is realized on the waveguide. The optical signal only passes through the amorphous GST to reconstruct the input vector, thereby changing the final calculation result of the optical matrix-vector multiplication.

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