Exceptional Points of Resonant States on a Periodic Slab

TL;DR

This paper investigates exceptional points in resonant states of a dielectric periodic slab, providing numerical and analytical insights into their properties and potential applications in photonics.

Contribution

It introduces an efficient numerical method to calculate EPs on a periodic slab and derives analytical results in the uniform limit, offering a simple platform for future studies.

Findings

EPs depend on geometric parameters of the slab

Analytical expressions are obtained for the uniform limit

The study highlights potential applications in photonics

Abstract

A special kind of degeneracies known as the exceptional points (EPs), for resonant states on a dielectric periodic slab, are investigated. Due to their unique properties, EPs have found important applications in lasing, sensing, unidirectional operations, etc. In general, EPs may appear in non-Hermitian eigenvalue problems, including those related to PT-symmetric systems and those for open dielectric structures (due to the existence of radiation loss). In this paper, we study EPs on a simple periodic structure: a slab with a periodic array of gaps. Using an efficient numerical method, we calculate the EPs and study their dependence on geometric parameters. Analytic results are obtained for the limit as the periodic slab approaches a uniform one. Our work provides a simple platform for further studies concerning EPs on dielectric periodic structures, their unusual properties and applications.