Polygon-based unified Fourier-modal approach for diffractive optics simulations

TL;DR

This paper introduces a unified Fourier-modal method for simulating diffractive optics, combining rigorous coupled wave analysis and dynamical diffraction theory, and applies it to nanoscale lamellar gratings with polygonal line profiles.

Contribution

The paper presents a novel formalism that unifies two existing theories and a computational approach that efficiently handles arbitrary grating profiles without relying on specific geometry models.

Findings

The new method accurately matches experimental data.

It simplifies the modeling of complex grating profiles.

It outperforms existing computational theories in speed and flexibility.

Abstract

In this article, we derive a theoretical formalism that unifies the rigorous coupled wave analysis and the dynamical diffraction theory. Based on this formalism, we design a computational approach for the diffraction calculation for the nanoscale lamellar gratings with an arbitrary line profile shape. In this approach, the gratings line profile is approximated as a polygon. This proves to be convenient since such an approach does not rely on the geometry model of the grating. We test the new approach against other computational theories and a synchrotron scattering experiment.