Tailoring Thermal Radiative Properties with Film-Coupled Concave Grating Metamaterials

TL;DR

This paper numerically studies film-coupled concave grating metamaterials, revealing spectrally-selective absorption in visible and near-infrared ranges due to magnetic polaritons and surface plasmon polaritons, with implications for energy and sensing applications.

Contribution

It introduces a detailed numerical analysis of film-coupled concave grating metamaterials, elucidating the mechanisms of localized MPs and SPPs and their dependence on geometric parameters.

Findings

Spectrally-selective absorption achieved in visible and near-infrared

Magnetic polaritons and surface plasmon polaritons identified as key mechanisms

Geometric parameters influence resonance peaks and directional responses

Abstract

This work numerically investigates the radiative properties of film-coupled metamaterials made of a two-dimensional metallic concave grating on a continuous metal film separated by an ultrathin dielectric spacer. Spectrally-selective absorption is demonstrated in the visible and near-infrared regime, and underlying mechanisms are elucidated to be either localized magnetic polaritons (MPs) or surface plasmon polaritons (SPPs). The unique behaviors of MPs and SPPs are explained with the help of electromagnetic field distributions at respective resonance frequencies. An inductor-capacitor model is utilized to further confirm the excitation of MP, while dispersion relation is used to understand the behaviors of different SPP modes. Geometric effects of ridge width and grating period on the resonance absorption peaks are discussed. Moreover, directional responses at oblique incidences for different polarization states are studied. Fundamental understanding gained here will facilitate the design of novel metamaterials in energy harvesting and sensing applications.