Algorithm for the rigorous coupled-wave analysis of grating diffraction

TLDR

Diffraction of light by periodic gratings is analyzed with a characteristic‑matrix formalism based on a rigorous coupled‑wave approach, which is especially convenient for modeling diffraction by nonuniform periodic structures. The authors propose a new algorithm to overcome numerical difficulties caused by inhomogeneous eigenmodes in grating analysis. The algorithm achieves stability by distinguishing growing and decaying inhomogeneous modes during computation. Numerical examples and comparisons with previous results demonstrate the algorithm’s performance.

Abstract

Diffraction of light by periodic gratings is analyzed with a characteristic-matrix formalism based on a rigorous coupled-wave approach. This formalism is particularly convenient for modeling the diffraction by nonuniform periodic structures. In order to overcome numerical difficulties that are due to inhomogeneous eigenmodes, we propose a new algorithm that remains stable for gratings of any thickness. We obtain the stability by distinguishing in the computation the growing and the decaying inhomogeneous modes. Numerical examples and comparisons with previous results are given.