Backaction in metasurface etalons

TL;DR

This paper investigates how the interaction between a metasurface and a mirror in etalons affects the metasurface's optical response, revealing that the mirror modifies the metasurface's polarizability and reflectivity beyond standard assumptions.

Contribution

It demonstrates that the mirror's presence renormalizes the metasurface's response, challenging the assumption of environment-independent reflectivity in Fabry-Perot models.

Findings

Mirror modifies metasurface polarizability

Reflectivity is environment-dependent due to mirror interaction

Layer-by-layer models capture qualitative features

Abstract

We consider the response of etalons created by a combination of a conventional mirror and a metasurface, composed of a periodic lattice of metal scatterers with a resonant response. This geometry has been used previously for perfect absorption, in so-called Salisbury screens, and for hybridization of localized plasmons with Fabry-Perot resonances. The particular aspect we address is if one can assume an environment-independent reflectivity for the metasurface when calculating the reflectivity of the composite system, as in a standard Fabry-Perot analysis, or whether the fact that the metasurface interacts with its own mirror image renormalizes its response. Using lattice sum theory, we take into account all possible retarded dipole-dipole interactions of scatterers in the metasurface amongst each other, and through the mirror. We show that while a layer-by-layer Fabry-Perot formalism captures the main qualitative features of metasurface etalons, in fact the mirror modifies both the polarizability and reflectivity of the metasurface in a fashion that is akin to Drexhage's modification of the radiative properties of a single dipole.