Quasi-bandgap behavior in non-Hermitian photonic crystals

Fuente: arXiv
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Autori principali: Xu, Jin, Cui, Daniel, Raman, Aaswath P.
Natura: Preprint
Pubblicazione: 2026
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author Xu, Jin
Cui, Daniel
Raman, Aaswath P.
author_facet Xu, Jin
Cui, Daniel
Raman, Aaswath P.
contents We investigate non-Hermitian photonic crystals in which the lossy and lossless constituents share the same real permittivity and differ only in their imaginary part. We characterize the complex band structure and reflection response of both one-dimensional (1D) and two-dimensional (2D) systems, and show that introducing even a small amount of material loss opens a quasi bandgap at the Brillouin-zone boundary. This quasi bandgap, absent in the lossless limit of the same structure, gives rise to sharp reflectivity peaks whose origin we explain through second-order perturbation theory. As an application of this behavior, we demonstrate a selective reflector combining a conventional photonic-crystal waveguide with a non-Hermitian photonic crystal, achieving wavelength-selective reflection with broadband absorption.
format Preprint
id arxiv_https___arxiv_org_abs_2604_01319
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Quasi-bandgap behavior in non-Hermitian photonic crystals
Xu, Jin
Cui, Daniel
Raman, Aaswath P.
Optics
We investigate non-Hermitian photonic crystals in which the lossy and lossless constituents share the same real permittivity and differ only in their imaginary part. We characterize the complex band structure and reflection response of both one-dimensional (1D) and two-dimensional (2D) systems, and show that introducing even a small amount of material loss opens a quasi bandgap at the Brillouin-zone boundary. This quasi bandgap, absent in the lossless limit of the same structure, gives rise to sharp reflectivity peaks whose origin we explain through second-order perturbation theory. As an application of this behavior, we demonstrate a selective reflector combining a conventional photonic-crystal waveguide with a non-Hermitian photonic crystal, achieving wavelength-selective reflection with broadband absorption.
title Quasi-bandgap behavior in non-Hermitian photonic crystals
topic Optics
url https://arxiv.org/abs/2604.01319