A symmetry-protected exceptional ring in a photonic crystal with negative index media

TL;DR

This paper demonstrates the numerical emergence of a symmetry-protected exceptional ring in a negative index photonic crystal, revealing new non-Hermitian topological phenomena in engineered optical materials.

Contribution

It introduces the first numerical analysis of SPERs in negative index media photonic crystals using GEVP, highlighting potential experimental observation.

Findings

SPER appears in the studied photonic crystal structure

SPER emerges at a finite frequency in simulations

Analysis suggests experimental observability of SPER

Abstract

Non-Hermitian topological band structures such as symmetry-protected exceptional rings (SPERs) can emerge for systems described by the generalized eigenvalue problem (GEVP) with Hermitian matrices. In this paper, we numerically analyze a photonic crystal with negative index media, which is described by the GEVP with Hermitian matrices. Our analysis using COMSOL Multiphysics demonstrates that a SPER emerges for photonic crystals composed of split-ring resonators and metal-wire structures. We expect that the above SPER can be observed in experiments as it emerges at a finite frequency.