Exceptional points for resonant states on parallel circular dielectric cylinders

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal

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Original languageEnglish
Pages (from-to)1659-1667
Number of pages9
Journal / PublicationJournal of the Optical Society of America B: Optical Physics
Volume36
Issue number6
Online published6 May 2019
Publication statusPublished - Jun 2019

Abstract

Exceptional points (EPs) are special parameter values of a non-Hermitian eigenvalue problem where eigenfunctions corresponding to a multiple eigenvalue coalesce. In optics, EPs are associated with a number of counterintuitive wave phenomena and have potential applications in lasing, sensing, mode conversion, and spontaneous emission processes. For open photonic structures, resonant states are complex-frequency solutions of the Maxwell's equations with outgoing radiation conditions. For open dielectric structures without material gain or loss, the eigenvalue problem for resonant states can have EPs, since it is non-Hermitian due to radiation losses. For applications in nanophotonics, it is important to understand EPs for resonant states on small finite dielectric structures consisting of conventional dielectric materials. To achieve this objective, we study EPs of resonant states on finite sets of parallel infinitely long circular dielectric cylinders with subwavelength radii. For systems with two, three, and four cylinders, we develop an efficient numerical method for computing EPs, present examples for second- and third-order EPs, and highlight their topological features. Our work provides insight to understanding EPs on more complicated photonic structures, and can be used as a simple platform to explore applications of EPs.