Angle-Resolved Thermal Emission Spectroscopy Characterization of Non-Hermitian Meta-Crystals

TL;DR

This paper introduces angle-resolved thermal emission spectroscopy (ARTES) as a novel technique to characterize the eigenmodes of non-Hermitian meta-crystals, revealing phenomena like BICs and Fermi arcs with high angular resolution.

Contribution

The work demonstrates a new spectroscopic platform, ARTES, for directly mapping dispersion relations and topological features in non-Hermitian photonic systems.

Findings

Detection of bound states in the continuum (BICs)

Observation of non-Hermitian Fermi arcs

Band inversion and exceptional points during thickness variation

Abstract

We establish the angle-resolved thermal emission spectroscopy (ARTES) as a new platform to characterize the intrinsic eigenmode properties of non-Hermitian systems. This method can directly map the dispersion of meta-crystals within the light cone with a high angular resolution. To illustrate its usefulness, we demonstrate the existence of bound states in the continuum (BICs) and non-Hermitian Fermi arcs in a planar corrugated meta-crystal by measuring its angle-resolved thermal emission spectra. We show that change in the thickness of the meta-crystal can induce a band inversion between a BIC and a radiative state, and a pair of exceptional points emerge when the band inversion occurs. With this approach, the band mapping of non-Hermitian photonic systems can become a relatively straightforward task.