Thin Element Approximation (TEA) vs. Fourier Modal Method (FMM) for Grating Modeling
Abstract
The Thin Element Approximation (TEA) is a widely-used method in Fourier optics to calculate the diffraction efficiency of gratings. However, it is also known that the approximation becomes inaccurate for smaller grating periods, means closer to the wavelength of light. In this example, two types of transmission gratings are selected to showcase this effect: sinusoidal and blazed. We use both TEA and FMM (also known as RWCA, which is rigorous) to analyze such gratings with varying period, and by comparing the results, we investigate the behavior of the two methods.
VirtualLab Fusion Configuration
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VirtualLab Fusion
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Grating Package
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Use Case
Analysis of Slanted Gratings for Lightguide Coupling
Different slanted grating geometries are selected from literature, with varying slant angle, fill factor, and modulation depth, and the diffraction efficiencies are calculated with the Fourier modal method (FMM).
Tutorial
Grating Order Analyzer
In VirtualLab Fusion, the Grating Order Analyzer can be used for convenient grating diffraction analysis, with results presented in various ways.
Tutorial
Configuration of Grating Structures by Using Interfaces
In VirtualLab Fusion, grating structures are configured in a “stack”, which can be constructed with either a sequence of interfaces or special media, depending on the geometry of the grating.