Electromagnetic Device Parameter Optimization via Time-Forward Simulation

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Solution Overview

Problem

Designing optical and electromagnetic devices with billions of parameters is challenging due to high memory footprint requirements for simulations, making it difficult to optimize structural parameters effectively.

Innovation Solution

A physics simulator using first-principles simulations with linear PDE systems and reduced dimensionality representation, employing time-forward simulation and backpropagation with Fourier transforms to optimize structural parameters efficiently, reducing memory footprint and computational cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If full first-principles simulations are performed for device optimization, then design accuracy and optimization quality are improved, but memory footprint and computational cost increase exponentially

Engineering Contradiction:
Improvedesign accuracyVSAvoidmemory footprint
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent segments the simulation process into two distinct phases: a forward simulation phase that computes device response, and a backward simulation phase that computes gradients. This temporal segmentation allows memory to be reused between phases rather than storing all intermediate results simultaneously, resolving the contradiction between achieving accurate first-principles optimization and managing memory footprint.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the computational parameters by using reduced-order models that approximate full first-principles simulations. These reduced-order models maintain sufficient accuracy for optimization purposes while dramatically reducing the memory and computational requirements, allowing design accuracy to be preserved without exponential resource scaling.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the number of design parameters is increased to capture full device functionality, then device performance and functionality are improved, but the complexity and computational burden of optimization increase

Engineering Contradiction:
Improvedevice functionalityVSAvoidoptimization complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements automatic differentiation that provides exact gradient feedback for all design parameters simultaneously. This feedback mechanism allows the optimization algorithm to efficiently navigate high-dimensional parameter spaces with billions of parameters, transforming the complexity burden into a manageable automated process that scales with device functionality.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces traditional numerical differentiation methods with automatic differentiation based on computational graph theory. This substitution eliminates the computational burden of finite difference methods while providing exact gradients, allowing the system to handle increased numbers of design parameters without proportional increases in optimization complexity.

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

3Ease of manufacture

If traditional numerical differentiation is used for optimization, then implementation simplicity is maintained, but computational cost and accuracy deteriorate

Engineering Contradiction:
Improveimplementation simplicityVSAvoidcomputational cost
Core Design Contradiction:
Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent substitutes traditional numerical differentiation with automatic differentiation. This replacement maintains implementation simplicity through automated computational graphs while dramatically reducing computational cost by eliminating the need for multiple perturbation simulations, providing exact gradients with a single forward-backward simulation pass.

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

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

Enables optimized design of devices with a nearly unlimited number of parameters, independent of human intuition, resulting in designs that outperform current state-of-the-art devices with reduced memory usage.

Implementation Method 1

A physics simulator using first-principles simulations with linear PDE systems

Methodology Applied
Scientific EffectFirst-principles simulations:

Implementation Method 2

linear PDE systems

Methodology Applied
Scientific EffectLinear partial differential equations:

Implementation Method 3

employing time-forward simulation and backpropagation with Fourier transforms

Methodology Applied
Scientific EffectFourier transforms:

Data Source

PatentUS11205022B2System and method for optimizing physical characteristics of a physical device
Publication Date: 2021.12.21 X DEVELOPMENT LLC
  • US11205022B2 patent drawing
  • US11205022B2 patent drawing
  • US11205022B2 patent drawing

AI summary

A method and system for optimizing structural parameters of an electromagnetic device is described that includes performing operations. The operations include performing a time-forward simulation of a field response in a simulated environment describing the electromagnetic device and extracting decomposition components from the field response to compute a loss value. The operations further include backpropagating the loss value backwards in time using the decomposition components to determine an influence of changes in the structural parameters of the electromagnetic device on the loss value. The operations further include generating a revised description of the electromagnetic device by updating the structural parameters to reduce the loss value.