Modeling the reflectivity of plasmonic ultrasharp groove arrays: general direction of light incidence

Abstract

The reflectivity of ultrasharp periodic groove arrays in a gold surface is studied for a general direction of light incidence. This includes the case of incident light propagating along the grooves. Two efficient numerical modeling approaches are presented, namely, a simple and approximate stack matrix method (SMM), which uses the mode index of gap-plasmon polaritons as an effective index, and a rigorous Green’s function surface integral equation method (GFSIEM). The results of the highly simple SMM show remarkable similarity to the exact results obtained with the rigorous GFSIEM, which reinforces the idea that the physics of light absorption in such structures is dominated by the coupling of light into plasmons.