title: Generation of adaptive coordinates and their use in the Fourier Modal Method.
abstract: We present an improvement of the standard Fourier Modal Method (FMM) for the analysis of lamellar gratings that is based on the use of automatically generated adaptive coordinates for arbitrarily shaped material profiles in the lateral plane of periodicity. This allows for an accurate resolution of small geometric features and/or large material contrasts within the unit. For dielectric gratings, we obtain considerable convergence accelerations. Similarly, for metallic gratings, our approach allows efficient and accurate computations of transmittance and reflectance coefficients into various Bragg orders, the spectral positions of Rayleigh anomalies, and field enhancement values within the grating structures.
authors.affiliation: Institut für Theoretische Festkörperphysik and DFG-Center for Functional Nanostructures, Karlsruher Institut für Technologie, Wolfgang-Gaede-St. 1, 76131 Karlsruhe, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Essig
authors.forename: Kurt
authors.initials: K
authors.lastname: Busch