Amplitude-Only Fourier Optical Processor for Low-Latency Matrix Convolution

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Solution Overview

Problem

Current electronic systems, such as GPUs and TPUs, face significant latency and computational power consumption issues when performing inference tasks, especially for large datasets and deep convolutional neural networks, due to the high demand for computational resources in convolution layers.

Innovation Solution

The development of analog amplitude-only Fourier optical processors using reprogrammable high-resolution spatial modulators like Digital Micromirror Devices (DMDs) for performing electro-optical convolutions between large matrices, enabling massively parallel and real-time processing with reduced latency and power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If GPU/TPU electronic systems are used for convolution operations, then computational accuracy and programmability are improved, but latency and power consumption increase significantly

Engineering Contradiction:
Improvecomputational accuracyVSAvoidlatency
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces electronic computational systems (GPUs/TPUs) with an optical computing system that uses light propagation and interference to perform convolution operations. The optical system uses spatial light modulators and Fourier transforming lenses to execute matrix multiplications at the speed of light, eliminating the sequential electronic computation bottleneck while maintaining computational accuracy through interference-based signal processing.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transitions from temporal computation (sequential electronic operations) to spatial computation (parallel optical operations). By encoding data in spatial dimensions and using optical field propagation to perform computations simultaneously across all data points, the system achieves massive parallelism and reduces latency by several orders of magnitude compared to sequential electronic processing.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If GPU/TPU electronic systems are used for convolution operations, then computational accuracy is improved, but power consumption increases significantly

Engineering Contradiction:
Improvecomputational accuracyVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent replaces energy-intensive electronic computation with optical computation that uses the wave nature of light to perform calculations. The optical system requires minimal power for modulating light fields rather than continuously powering high-speed electronic switches and memory access circuits, dramatically reducing power consumption while maintaining computational accuracy through optical interference and diffraction.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The optical system performs computations using the natural propagation and interference of light fields without requiring continuous external energy input during the computation process. The light itself carries and processes the information, with computation emerging from the physical interaction of light waves rather than requiring active electronic control at each computational step.

Inventive Principle:
Principle #25Self-service

3Loss of time

If optical processing systems are used, then latency and power consumption are reduced, but data handling challenges and programmability speed increase

Engineering Contradiction:
ImprovelatencyVSAvoidprogrammability
Core Design Contradiction:
Loss of timeVSEase of operation

Solution Approach 1:

The patent introduces spatial light modulators as intermediary devices that bridge electronic data input and optical processing. These modulators convert electronic data into optical field distributions that can be manipulated by the optical system, and can be reprogrammed electronically to change the computational task, thus providing both fast optical processing and flexible programmability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system pre-configures the optical processing paths and interference patterns through the spatial light modulators before computation begins. By preparing the optical fields and modulation patterns in advance, the system eliminates runtime reconfiguration delays while maintaining the ability to perform different computational tasks through pre-loaded modulation patterns.

Inventive Principle:
Principle #10Preliminary action

4Productivity

If larger matrices are processed, then computational capability is improved, but latency and computational resource demand increase

Engineering Contradiction:
Improvecomputational capabilityVSAvoidlatency
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent encodes large matrices in spatial dimensions rather than processing them sequentially in time. By mapping matrix elements to spatial positions in optical fields and using parallel optical propagation to perform operations on all elements simultaneously, the system achieves computational capability that scales with spatial resolution rather than being limited by sequential processing speed, thus maintaining low latency even for large matrices.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The optical system divides the processing of large matrices into multiple spatial channels that are processed in parallel through the optical field. Each spatial location in the optical field represents a separate computational channel, allowing the system to handle large matrices by distributing computations across many parallel spatial pathways rather than processing elements sequentially.

Inventive Principle:
Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

These optical processors achieve latency 100 times lower than current GPU accelerators and throughput of up to 4-Peta operations per second, outperforming traditional electronic systems in classification tasks with high accuracy, such as 98% on MNIST and 54% on CIFAR-10 datasets, while reducing processing time by one order of magnitude.

Implementation Method 1

performing electro-optical convolutions between large matrices (e.g. feature maps corresponding to images and matrices used as kernels in neural networks) displayed by reprogrammable high-resolution amplitude-only spatial modulators based on two stages of Fourier Transforms (FT)

Methodology Applied
Scientific EffectFourier transform:

Implementation Method 2

analog amplitude-only (AO) electro-optical convolutions between large matrices displayed by reprogrammable high-resolution amplitude-only spatial modulators

Methodology Applied
Scientific EffectElectro-optical modulation: Electro-Optic Effects

Data Source

PatentUS20230298145A1Massively parallel amplitude-only optical processing system and methods for machine learning
Publication Date: 2023.09.21 GEORGE WASHINGTON UNIVERSITY
  • US20230298145A1 patent drawing
  • US20230298145A1 patent drawing
  • US20230298145A1 patent drawing

AI summary

Amplitude-only Fourier optical processors is capable of processing large-scale matrices in a single time-step and microsecond-short latency. The processors may have a 4f optical system architecture and may employ reprogrammable high-resolution amplitude-only spatial modulators, such as Digital Micromirror Devices (DMD). In addition, methods are provided for obtaining amplitude-only electro-optical convolutions between large matrices displayed by the DMDs. The large matrices on which convolution is performed may be feature maps corresponding to images and kernel matrices used in neural networks classification systems. Analog optical convolutional neural networks are also provided that perform accurate classification tasks on large matrices. In addition, methods are provided for off-chip training the analog optical convolutional neural networks. The training includes building an accurate physical model for the analog optical processor and performing computer simulations of the optical processor according to the physical model. The methods do not need to employ any interferometric scheme.