Resonant Absorption of TE-Polarized Light at the Surface of a Dielectric-Coated Metal Grating

Abstract

Mesoscopic interaction of transverse electric (TE)-polarized light with metal gratings requires a dielectric coating on the metal surfaces to support a waveguide mode for optical resonances simulating those of surface plasmon resonances for transverse magnetic (TM)-polarized light. Here, we show a resonance-induced absorption of TE-polarized light at a dielectric-coated metal grating. The resonance is identified to have a Bloch wave nature, existing only for its even-order modes, restricted by the coupling phase matching conditions in a reflection configuration mode. It is also shown that the resonance properties are largely subjected to the size of the grating grooves, where localized cavity mode can be excited for large-size grooves, leading to broad absorption peaks due to nonresonant losses and bringing in new absorption peaks resulting from cavity resonances in the grooves.