Fabry-Pérot quasinormal modes for topological edge states

Fuente: arXiv
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Autori principali: Martí-Sabaté, Marc, Vial, Benjamin, Wiltshaw, Richard, Guenneau, Sébastien, Craster, Richard V.
Natura: Preprint
Pubblicazione: 2025
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author Martí-Sabaté, Marc
Vial, Benjamin
Wiltshaw, Richard
Guenneau, Sébastien
Craster, Richard V.
author_facet Martí-Sabaté, Marc
Vial, Benjamin
Wiltshaw, Richard
Guenneau, Sébastien
Craster, Richard V.
contents Topological waveguides supporting quantum valley Hall interfacial states confine waves to interfaces and, due to topological protection, are resistant to backscattering even in the presence of defects. These topological insulators are typically studied by means of an infinite spectral problem. However, practical implementations are necessarily finite. In this work, we propose an alternative framework for analysing topologically non-trivial states in open, finite systems. Our approach is based on a Quasinormal Modal Expansion Method (QMEM), which directly characterizes the existence and excitation of these modes within the open system. The resulting spectrum is complex and discrete and fully describes the topologically non-trivial states, revealing an analogy of topological mode steering as a dispersive Fabry-Pérot cavity, with a dispersion relation closely related to that of the corresponding infinite (Floquet-Bloch) ribbon problem. Our results illustrate how topologically protected waveguiding can be understood in terms of leaky cavity modes and offers a powerful framework for analysing finite topological devices.
format Preprint
id arxiv_https___arxiv_org_abs_2508_07767
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Fabry-Pérot quasinormal modes for topological edge states
Martí-Sabaté, Marc
Vial, Benjamin
Wiltshaw, Richard
Guenneau, Sébastien
Craster, Richard V.
Applied Physics
Topological waveguides supporting quantum valley Hall interfacial states confine waves to interfaces and, due to topological protection, are resistant to backscattering even in the presence of defects. These topological insulators are typically studied by means of an infinite spectral problem. However, practical implementations are necessarily finite. In this work, we propose an alternative framework for analysing topologically non-trivial states in open, finite systems. Our approach is based on a Quasinormal Modal Expansion Method (QMEM), which directly characterizes the existence and excitation of these modes within the open system. The resulting spectrum is complex and discrete and fully describes the topologically non-trivial states, revealing an analogy of topological mode steering as a dispersive Fabry-Pérot cavity, with a dispersion relation closely related to that of the corresponding infinite (Floquet-Bloch) ribbon problem. Our results illustrate how topologically protected waveguiding can be understood in terms of leaky cavity modes and offers a powerful framework for analysing finite topological devices.
title Fabry-Pérot quasinormal modes for topological edge states
topic Applied Physics
url https://arxiv.org/abs/2508.07767