Hybrid meshes for the modeling of optical nanostructures with the surface integral equation method

Recently, hybrid metasurfaces built from meta-atoms that combine plasmonic and dielectric materials have emerged thanks to their interesting electromagnetic properties. In this study, we resort to surface integral equations (SIEs) and the method of moments (MoM) to model plasmonic and hybrid nanostructures. A surface meshing approach is used to discretize the equations, and the Poggio-Miller-Chang-Harrington-Wu-Tsai (PMCHWT) formulation is considered. To model experimentally relevant nanostructures efficiently, we combine triangular and quadrilateral elements with Rao-Wilton-Glisson (RWG), rooftop, and hybrid basis functions, while an element-by-element approach is used to coalesce triangular and quadrilateral elements. The accuracy and numerical effort associated with each type of mesh are carefully assessed, using a variety of geometries that include one or more materials. Finally, we observe that hybrid meshes are able to accurately reproduce complex scattering features with a significantly reduced number of unknowns.