Theory on the scattering of light and surface plasmon polaritons by arrays of holes and dimples in a metal film

TL;DR

This paper presents a theoretical study of how arrays of holes and dimples in metal films scatter light and surface plasmon polaritons, introducing a modal expansion method capable of handling complex geometries and real metals.

Contribution

It introduces a novel modal expansion formalism for analyzing light and SPP scattering by large arrays of holes or dimples in metal films, applicable to real metals with thousands of indentations.

Findings

Single holes can scatter a significant fraction of light into SPPs.

Holes and dimples scatter SPPs into light with similar efficiencies if the dimple depth exceeds its radius.

Normalized emittances in different channels depend differently on the number of holes.

Abstract

The scattering of light and surface plasmon polaritons (SPPs) by finite arrays of either holes or dimples in a metal film is treated theoretically. A modal expansion formalism, capable of handling real metals with up to thousands of indentations, is presented. Computations based on this method demonstrate that a single hole scatters a significant fraction of incoming light into SPPs. It is also observed that holes and dimples scatter SPPs into light with similar efficiencies, provided the depth of the dimple is larger than its radius. Finally, it is shown that in arrays the normalized-to-area emittances in the out-of-plane and SPP channels present different dependences with the number of holes.