First-order perturbation theory of eigenmodes for systems with interfaces

We present an exact first-order perturbation theory for eigenmodes in systems with interfaces causing material discontinuities. We show that when interfaces deform, higher-order terms of the perturbation series can contribute to the eigenmode frequencies in first order in the deformation depth. In s...

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Bibliographic Details
Published in:Physical review research 2023-03, Vol.5 (1), p.013209, Article 013209
Main Authors: Sztranyovszky, Z., Langbein, W., Muljarov, E. A.
Format: Article
Language:English
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Summary:We present an exact first-order perturbation theory for eigenmodes in systems with interfaces causing material discontinuities. We show that when interfaces deform, higher-order terms of the perturbation series can contribute to the eigenmode frequencies in first order in the deformation depth. In such cases, the first-order approximation is different from the usual diagonal approximation and its single-mode result. Extracting additional first-order corrections from all higher-order terms enables us to recover the diagonal formalism in a modified form. A general formula for the single-mode first-order correction to electromagnetic eigenmodes in systems with interfaces is derived, capable of treating dispersive, magnetic, and chiral materials of arbitrary shape.
ISSN:2643-1564
2643-1564
DOI:10.1103/PhysRevResearch.5.013209