Multi-reflection model of subwavelength grating diffraction based on simplified modal method

TL;DR

This paper introduces a multi-reflection model for subwavelength grating diffraction based on a simplified modal method, providing a clearer physical understanding and practical resonance conditions for designing guided mode resonance gratings.

Contribution

The paper presents a novel multi-reflection model using a simplified modal method, validated against rigorous coupled wave analysis, and introduces resonance conditions for easier grating design.

Findings

Model agrees well with rigorous coupled wave analysis

Provides a clear physical view of diffraction process

Offers resonance conditions for GMR grating design

Abstract

A multi-reflection model of grating diffraction based on the simplified modal method is proposed. Simulation results for a guided mode resonance Brewster grating using our method and rigorous coupled wave analysis are presented to verify our model. The solution of our method is in good agreement with that of rigorous coupled wave analysis. Benefiting from its clear physical view, this model helps us to better understand the diffraction process inside subwavelength gratings. On the basis of the multi-reflection model, we developed a matrix Fabry-Perot (FP) resonance condition and a single-mode resonance condition to evaluate the resonance wavelength. These resonance conditions may be helpful for simplifying design of guided mode resonance (GMR) gratings.