Broadband Green's Function for Photonic Crystal Simulation

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Solution Overview

Problem

Existing electromagnetic simulation tools for smart devices made of metamaterials, photonic crystals, and phononic crystals are computationally complex, inefficient, and inaccurate, particularly when analyzing broadband frequency or wavelength ranges, and require repetitive calculations for small geometric changes.

Innovation Solution

The Broadband Green's function computer simulation technique is employed, which uses low wavenumber extraction to obtain frequency-independent modal solutions efficiently and allows for fast convergence of modal expansions, enabling simulations across a wide frequency range and reducing the need for repetitive calculations when geometry changes are made.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional electromagnetic simulation tools (FDTD, FEM, MoM) are used to model wave behavior in metamaterials and photonic crystals, then the simulations can capture complex wave interactions and scattering effects, but the computational complexity increases significantly and the efficiency decreases

Engineering Contradiction:
Improvesimulation accuracyVSAvoidcomputational efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The simulation problem is segmented by separating the periodic structure analysis from the specific device analysis. The Green's function pre-computation handles the periodic lattice once, and then this result is reused for multiple device configurations, dividing the computational task into efficient reusable components

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The Green's function is computed in advance for the periodic lattice before the actual device simulation. This preliminary computation captures all the wave scattering information from the periodic elements, so that subsequent device analyses can proceed without re-computing these fundamental interactions

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If traditional simulation methods compute solutions one frequency or wavelength at a time, then the accuracy for specific frequency points is maintained, but the time required for broadband analysis increases significantly

Engineering Contradiction:
Improvefrequency point accuracyVSAvoidbroadband analysis time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The Green's function serves multiple frequency points simultaneously. By formulating the solution in terms of Green's function that encodes the frequency-dependent wave interactions, a single pre-computation enables accurate results across a broad frequency range without repeating the entire calculation

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Measurement precision

If the entire calculation is repeated for small geometric changes (adding impurity, defect, displacement), then the accuracy for the modified structure is ensured, but the computational productivity decreases

Engineering Contradiction:
Improvestructure-specific accuracyVSAvoiddesign iteration speed
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

Only the local region containing the geometric modification is re-analyzed using the pre-computed Green's function. The unchanged parts of the periodic structure rely on the pre-existing Green's function results, so computational effort is concentrated only where the geometry actually changes

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The approach allows easy modification of geometric parameters (adding impurities, defects, displacements) by simply changing the input geometry description while reusing the same Green's function framework, enabling rapid parametric studies without full re-computation

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS11087043B2Full wave simulations of photonic crystals and metamaterials using the broadband green's functions
Publication Date: 2021.08.10 TSANG LEUNG W
  • US11087043B2 patent drawing
  • US11087043B2 patent drawing
  • US11087043B2 patent drawing

AI summary

Broadband Green's function computing technique that employs low wavenumber extraction, obtains fast frequency independent modal band solutions and achieves fast convergence of modal expansions, is used to model and design electromagnetic wave behavior of signals in artificial materials with periodic structures, including metamaterials, photonic crystals, and phononic crystals, which are used for smart microwave devices, photonic devices, and acoustic devices. The Broadband Green's function is a general response function for artificial materials and is used to model bandgaps, bandpasses, impurities, defects, displacements of scatterers, and to formulate integral equations for periodic scatters in a finite volume. Designs of metamaterials, photonic crystals, and phononic crystals enable controlling the waves through bandpasses, bandgaps, surface states, polarizations, defects, absorption, enhancement, refraction, substrates, and guidance. The Broadband Green's function technique is used in computer simulations to analyze wave behavior over a broad frequency range, which improves design optimization of smart microwave and photonic devices.