All-optical permittivity-asymmetric quasi-bound states in the continuum

Abstract Resonances are usually associated with finite systems—the vibrations of clamped strings in a guitar or the optical modes in a cavity defined by mirrors. In optics, resonances may be induced in infinite continuous media via periodic modulations of their optical properties. Here we demonstrat...

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Main Authors: Rodrigo Berté, Thomas Possmayer, Andreas Tittl, Leonardo de S. Menezes, Stefan A. Maier
Format: Article
Language:English
Published: Nature Publishing Group 2025-05-01
Series:Light: Science & Applications
Online Access:https://doi.org/10.1038/s41377-025-01843-9
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author Rodrigo Berté
Thomas Possmayer
Andreas Tittl
Leonardo de S. Menezes
Stefan A. Maier
author_facet Rodrigo Berté
Thomas Possmayer
Andreas Tittl
Leonardo de S. Menezes
Stefan A. Maier
author_sort Rodrigo Berté
collection DOAJ
description Abstract Resonances are usually associated with finite systems—the vibrations of clamped strings in a guitar or the optical modes in a cavity defined by mirrors. In optics, resonances may be induced in infinite continuous media via periodic modulations of their optical properties. Here we demonstrate that periodic modulations of the permittivity of a featureless thin film can also act as a symmetry-breaking mechanism, allowing the excitation of photonic quasi-bound states in the continuum (qBICs). By interfering two ultrashort laser pulses in the unbounded film, transient resonances can be tailored through different parameters of the pump beams. We show that the system offers resonances tunable in wavelength and quality-factor, and spectrally selective enhancement of third-harmonic generation. Due to a fast decay of the permittivity asymmetry, we observe ultrafast dynamics, enabling time-selective near-field enhancement with picosecond precision. Optically induced permittivity asymmetries may be exploited in on-demand weak to ultrastrong light-matter interaction regimes and light manipulation at dynamically chosen wavelengths in lithography-free metasurfaces.
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series Light: Science & Applications
spelling doaj-art-e1cc926105144806b3115a7c82f92a472025-08-20T03:45:32ZengNature Publishing GroupLight: Science & Applications2047-75382025-05-0114111110.1038/s41377-025-01843-9All-optical permittivity-asymmetric quasi-bound states in the continuumRodrigo Berté0Thomas Possmayer1Andreas Tittl2Leonardo de S. Menezes3Stefan A. Maier4Chair in Hybrid Nanosystems, Nanoinstitut München, Fakultät für Physik, Ludwig-Maximilians-Universität MünchenChair in Hybrid Nanosystems, Nanoinstitut München, Fakultät für Physik, Ludwig-Maximilians-Universität MünchenChair in Hybrid Nanosystems, Nanoinstitut München, Fakultät für Physik, Ludwig-Maximilians-Universität MünchenChair in Hybrid Nanosystems, Nanoinstitut München, Fakultät für Physik, Ludwig-Maximilians-Universität MünchenSchool of Physics and Astronomy, Monash UniversityAbstract Resonances are usually associated with finite systems—the vibrations of clamped strings in a guitar or the optical modes in a cavity defined by mirrors. In optics, resonances may be induced in infinite continuous media via periodic modulations of their optical properties. Here we demonstrate that periodic modulations of the permittivity of a featureless thin film can also act as a symmetry-breaking mechanism, allowing the excitation of photonic quasi-bound states in the continuum (qBICs). By interfering two ultrashort laser pulses in the unbounded film, transient resonances can be tailored through different parameters of the pump beams. We show that the system offers resonances tunable in wavelength and quality-factor, and spectrally selective enhancement of third-harmonic generation. Due to a fast decay of the permittivity asymmetry, we observe ultrafast dynamics, enabling time-selective near-field enhancement with picosecond precision. Optically induced permittivity asymmetries may be exploited in on-demand weak to ultrastrong light-matter interaction regimes and light manipulation at dynamically chosen wavelengths in lithography-free metasurfaces.https://doi.org/10.1038/s41377-025-01843-9
spellingShingle Rodrigo Berté
Thomas Possmayer
Andreas Tittl
Leonardo de S. Menezes
Stefan A. Maier
All-optical permittivity-asymmetric quasi-bound states in the continuum
Light: Science & Applications
title All-optical permittivity-asymmetric quasi-bound states in the continuum
title_full All-optical permittivity-asymmetric quasi-bound states in the continuum
title_fullStr All-optical permittivity-asymmetric quasi-bound states in the continuum
title_full_unstemmed All-optical permittivity-asymmetric quasi-bound states in the continuum
title_short All-optical permittivity-asymmetric quasi-bound states in the continuum
title_sort all optical permittivity asymmetric quasi bound states in the continuum
url https://doi.org/10.1038/s41377-025-01843-9
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