Fast Fourier factorization for differential method and RCWA: a powerful tool for the modeling of non-lamellar metallic diffraction gratings

摘要

The rigorous coupled-wave analysis (RCWA), also known as Fourier modal method, is one of the most popular methods for the modeling of diffraction gratings. It has been proven to be particularly effective for lamellar gratings. However, for non-lamellar metallic gratings, in TM polarization, the differential method (DM) or the RCWA need to be associated with the fast Fourier factorization (FFF) to provide more accurate solutions. In this study, we present the effectiveness of the FFF when it is associated with the DM and the RCWA for different grating's profiles, and we show how to circumvent on the case where the FFF can diverge when the metal permittivity is close to a pure negative real value.