Comparisons of enhanced absorption in closely-coupled grating-mirror and random particle-mirror systems

Abstract

The grating-mirror geometry is a particularly rich plasmonic system due to the coupling of localized and global modes, and it is applicable to negative index materials, plasmonic imaging, and spectral filters. Recently absorption in sub-percolative films was found to be greatly enhanced by the addition of a mirror - a situation that is also reasonably modeled by a grating-mirror geometry. A great deal of attention has been focused on the coupling of barely-sub-wavelength periodic grating modes to surface plasmon polaritons that exhibit sharp spectral features. In contrast, island films have only quasi-periodicity at a few tens of nanometers, and produce broader spectral features, suggesting the influence of localized surface plasmons. In this work we examine how absorption is affected by variations in geometry of grating-mirror systems, to identify basic physics for future investigations of particle-mirror systems.