Numerical analysis of a slit-groove diffraction problem

We present a comparison among several fully-vectorial methods applied to a basic scattering problem governed by the physics of the electromagnetic interaction between subwavelength apertures in a metal film. The modelled structure represents a slit-groove scattering problem in a silver film deposited on a glass substrate. The benchmarked methods, all of which use in-house developed software, include a broad range of fully-vectorial approaches from finite-element methods, volume-integral methods, and finite-difference time domain methods, to various types of modal methods based on different expansion techniques.