Resonant states of structured photonic time crystals

Fuente: arXiv
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Main Authors: Valero, Adrià Canós, Gladyshev, Sergei, Globosits, David, Rotter, Stefan, Muljarov, Egor A., Weiss, Thomas
Format: Preprint
Published: 2025
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author Valero, Adrià Canós
Gladyshev, Sergei
Globosits, David
Rotter, Stefan
Muljarov, Egor A.
Weiss, Thomas
author_facet Valero, Adrià Canós
Gladyshev, Sergei
Globosits, David
Rotter, Stefan
Muljarov, Egor A.
Weiss, Thomas
contents Photonic time crystals (PTCs) are spatially uniform media with periodic modulation in time, enabling momentum bandgaps and the parametric amplification of light. While their potential in optical systems is very promising, practical implementations require temporally modulating nanostructures of finite size, for which the physics is no longer governed by bulk properties but by resonant states, or quasinormal modes. Despite their importance, a quantitative theory describing the dynamics of these modes has been missing -- a gap we address here by developing a comprehensive resonant state theory for PTCs with arbitrary geometry. Our framework provides a detailed understanding of the resonant behavior of "structured" PTCs and uncovers several fundamental phenomena. For weak modulations, we find a universal quadratic dependence of the eigenfrequencies on the modulation amplitude. Moreover, each static resonant state gives rise to an infinite ladder of new eigenmodes, spaced by integer multiples of the modulation frequency. Crucially, we show that parametric amplification in these systems arises from a fundamentally resonant process, not captured by the momentum bandgap picture of "bulk" PTCs. We apply our theory to a realistic Bragg microcavity, demonstrating the design of tailored parametric resonances. Due to its generality and predictive power, our approach lays the foundation for the systematic study and engineering of structured PTCs, advancing the emerging field of space-time optics.
format Preprint
id arxiv_https___arxiv_org_abs_2506_01472
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Resonant states of structured photonic time crystals
Valero, Adrià Canós
Gladyshev, Sergei
Globosits, David
Rotter, Stefan
Muljarov, Egor A.
Weiss, Thomas
Optics
Photonic time crystals (PTCs) are spatially uniform media with periodic modulation in time, enabling momentum bandgaps and the parametric amplification of light. While their potential in optical systems is very promising, practical implementations require temporally modulating nanostructures of finite size, for which the physics is no longer governed by bulk properties but by resonant states, or quasinormal modes. Despite their importance, a quantitative theory describing the dynamics of these modes has been missing -- a gap we address here by developing a comprehensive resonant state theory for PTCs with arbitrary geometry. Our framework provides a detailed understanding of the resonant behavior of "structured" PTCs and uncovers several fundamental phenomena. For weak modulations, we find a universal quadratic dependence of the eigenfrequencies on the modulation amplitude. Moreover, each static resonant state gives rise to an infinite ladder of new eigenmodes, spaced by integer multiples of the modulation frequency. Crucially, we show that parametric amplification in these systems arises from a fundamentally resonant process, not captured by the momentum bandgap picture of "bulk" PTCs. We apply our theory to a realistic Bragg microcavity, demonstrating the design of tailored parametric resonances. Due to its generality and predictive power, our approach lays the foundation for the systematic study and engineering of structured PTCs, advancing the emerging field of space-time optics.
title Resonant states of structured photonic time crystals
topic Optics
url https://arxiv.org/abs/2506.01472