Modal Analysis of Gratings With Conducting Strip-Loaded Bars and Sandwiched Between Multiple Dielectric Layers

Abstract

This communication describes a full-wave modal analysis of plane-wave scattering by periodic arrays of penetrable conducting bars with strip covers on both the lower and upper surfaces of each ridge to create iris-type slits across groove apertures, which altogether is sandwiched by multiple dielectric layers on both sides of the gratings. The approach entails the moment method using parallel-plate waveguide cavity Green's functions and a numerical spectral-domain Green's function for planar stratified media accompanied by the Floquet theorem. Computed results obtained from codes written based on this formulation are validated with those simulated by a commercial full-wave software solver as well as results from the literature. Validation is performed in terms of reflection and transmission spectra as well as modal dispersion. The new parameters arising from the special complex geometry herein studied provide the means to enhance the performances of various applications such as beam deflectors, mode converters, and grating couplers, as well as the resolution of diffraction gratings in the context of spectroscopy. Measurement results acquired from experimentations carried out on a manufactured grating that corroborate well with theoretical predictions are also presented.