Experimental investigation of the thermal emission cross-section of nano-resonators using hierarchical Poisson-disk distributions

TL;DR

This paper presents an experimental method to measure the thermal emission cross-section of nano-resonators using a hyperuniform distribution, revealing that the emission can be treated as a sum of independent nanoantenna contributions, with results showing a resonance cross-section significantly larger than theoretical absorption limits.

Contribution

It introduces a novel measurement technique employing hierarchical Poisson-disk distributions to directly determine the emission cross-section of nano-resonators, overcoming previous measurement challenges.

Findings

Emission cross-section at resonance is about λ₀²/3.

Measured cross-section exceeds the theoretical maximum absorption.

Method can be applied to measure extinction cross-sections.

Abstract

Effective cross-sections of nano-objects are fundamental properties that determine their ability to interact with light. However, measuring them for individual resonators directly and quantitatively remains challenging, particularly because of the very low signals involved. Here, we experimentally measure the thermal emission cross-section of metal-insulator-metal nano-resonators using a stealthy hyperuniform distribution based on a hierarchical Poisson-disk algorithm. In such distributions, there are no long-range interactions between antennas, and we show that the light emitted by the metasurface behaves as the sum of cross-sections of independent nanoantennas, enabling direct retrieval of the single resonator contribution. The emission cross-section at resonance is found to be of the order of $\mathbf{\lambda_0^2/3}$, a value that is nearly three times larger than the theroretical maximal absorption cross-section of a single particle but remains smaller than the maximal extinction cross-section. This measurement technique can be generalized to any single resonator cross-section, and we also apply it here to the extinction cross-section.