Kirchhoff's metasurfaces

TL;DR

This paper investigates the thermo-optical properties of plasmonic perfect absorber metasurfaces at mid-infrared wavelengths, demonstrating their potential for efficient light-to-heat conversion and thermal radiation in sensor applications.

Contribution

It provides experimental validation of Kirchhoff's law in plasmonic metasurfaces and discusses design principles for optimizing photo-thermal conversion.

Findings

Reciprocity of absorbance and emittance confirmed experimentally.

Au-Si-Au structures achieved highest light-to-heat efficiency.

Enhanced thermal radiation correlates with strong optical absorption.

Abstract

Thermo-optical properties of the nanodisc and metal hole array plasmonic perfect absorber (PPA) metasurfaces were designed and characterised at midinfrared wavelengths. Both, light emitter and detector systems are highly thought after for the future sensor networks in the internet-of-things for various spectral domains. Reciprocity of the absorbance and emittance is shown experimentally, i.e., the PPAs are following Kirchhoff's law where the patterns exhibiting a strong optical absorption were found enhanced thermal radiation. Design principles and scaling for photo-thermal conversion are discussed. The highest efficiency of light-to-heat and heat-to-radiation were obtained for the Au-Si-Au structures.