Polarization-Controlled Coherent Phonon Generation in Acousto-Plasmonic Metasurfaces

TL;DR

This paper demonstrates how polarization-controlled plasmonic metasurfaces can serve as efficient, tunable transducers for high-frequency coherent phonons, advancing nanophononics and phonon laser development.

Contribution

It introduces a novel design of plasmonic metasurfaces capable of generating tunable, high-frequency phonons with polarization-dependent control, filling a gap in acoustic nanoscience.

Findings

Metasurfaces act as efficient photon-phonon transducers.

Spectral dependence on excitation rate and laser polarization.

Potential for engineering phononic metasurfaces.

Abstract

Acoustic vibrations at the nanoscale (GHz-THz frequencies) and their interactions with electrons, photons and other excitations are the heart of an emerging field in physics: nanophononics. The design of ultrahigh frequency acoustic-phonon transducers, with tunable frequency, and easy to integrate in complex systems is still an open and challenging problem for the development of acoustic nanoscopies and phonon lasers. Here we show how an optimized plasmonic metasurface can act as a high-frequency phonon transducer. We report pump-probe experiments in metasurfaces composed of an array of gold nanostructures, revealing that such arrays can act as efficient and tunable photon-phonon transducers, with a strong spectral dependence on the excitation rate and laser polarization. We anticipate our work to be the starting point for the engineering of phononic metasurfaces based on plasmonic nanostructures.