2025-06-24 ミュンヘン大学（LMU）
＜関連情報＞
- https://www.lmu.de/en/newsroom/news-overview/news/nanophysics-a-question-of-resonance.html
- https://www.nature.com/articles/s41377-025-01843-9
連続体における全光誘電率非対称準結合状態 All-optical permittivity-asymmetric quasi-bound states in the continuum
Rodrigo Berté,Thomas Possmayer,Andreas Tittl,Leonardo de S. Menezes & Stefan A. Maier
Light: Science & Applications Published:07 May 2025
DOI:https://doi.org/10.1038/s41377-025-01843-9
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.
