Adaptive perfectly matched layer for Wood's anomalies in diffraction gratings

TL;DR

This paper introduces an adaptive perfectly matched layer (APML) that improves absorption of diffracted waves near grazing angles in diffraction grating simulations, enhancing modeling accuracy for Wood's anomalies.

Contribution

The paper presents a novel APML design with coordinate stretching tailored to incident fields and grating parameters, improving absorption near Wood's anomalies in FEM simulations.

Findings

APML outperforms classical PML in absorbing near grazing angles.

Numerical results show improved accuracy in diffraction grating modeling.

APML effectively handles Wood's anomalies in dielectric slit gratings.

Abstract

We propose an Adaptive Perfectly Matched Layer (APML) to be used in diffraction grating modeling. With a properly tailored co-ordinate stretching depending both on the incident field and on grating parameters, the APML may efficiently absorb diffracted orders near grazing angles (the so-called Wood's anomalies). The new design is implemented in a finite element method (FEM) scheme and applied on a numerical example of a dielectric slit grating. Its performances are compared with classical PML with constant stretching coefficient.