Emergent resonances in a thin film tailored by optically-induced small permittivity asymmetries

Fuente: arXiv
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Auteurs principaux: Berté, Rodrigo, Possmayer, Thomas, Tittl, Andreas, Menezes, Leonardo de S., Maier, Stefan A.
Format: Preprint
Publié: 2024
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author Berté, Rodrigo
Possmayer, Thomas
Tittl, Andreas
Menezes, Leonardo de S.
Maier, Stefan A.
author_facet Berté, Rodrigo
Possmayer, Thomas
Tittl, Andreas
Menezes, Leonardo de S.
Maier, Stefan A.
contents 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 $\textit{quasi}$-bound states in the continuum ($\textit{q}$BICs). 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.
format Preprint
id arxiv_https___arxiv_org_abs_2403_05730
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Emergent resonances in a thin film tailored by optically-induced small permittivity asymmetries
Berté, Rodrigo
Possmayer, Thomas
Tittl, Andreas
Menezes, Leonardo de S.
Maier, Stefan A.
Optics
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 $\textit{quasi}$-bound states in the continuum ($\textit{q}$BICs). 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.
title Emergent resonances in a thin film tailored by optically-induced small permittivity asymmetries
topic Optics
url https://arxiv.org/abs/2403.05730