Non-Hermitian corner skin effect in a two-dimensional photonic crystal

TL;DR

This paper investigates non-Hermitian topological phenomena in a 2D photonic crystal, revealing unique skin effects and edge states due to complex eigenfrequency topology, with implications for experimental photonics.

Contribution

It demonstrates non-Hermitian skin effects and topological edge states in a continuous 2D photonic system, expanding understanding beyond tight-binding models.

Findings

Non-Hermitian skin effect occurs at edges and corners.

Complex eigenfrequencies exhibit nontrivial topological properties.

Identifies non-Hermitian topological edge states in a photonic crystal.

Abstract

We numerically study topological effects of electromagnetic (EM) waves in a two-dimensional (2D) non-Hermitian photonic crystal (PhC) composed of lossy magneto-optical materials. In this system, not only the EM wavefunctions but also the complex eigenfrequencies exhibit nontrivial topological properties. We demonstrate that the non-Hermitian skin effect, protected by point gaps in the complex eigenfrequency spectrum, emerges at both the edges and corners of truncated structures. This phenomenon has no counterpart in Hermitian systems. In addition, we identify non-Hermitian topological edge states originating from the nontrivial topology of the bulk bands. While most previous studies of non-Hermitian topology have focused on tight-binding models, our work addresses a continuous photonic system, providing a more realistic platform and offering a concrete route toward experimental realization of non-Hermitian effects.