Coupled acoustoplasmonic resonators: the role of geometrical symmetries

TL;DR

This paper investigates how breaking mirror symmetries in coupled acoustoplasmonic resonators influences their optical and mechanical responses, revealing new torsional modes and mode coupling effects relevant for designing advanced acousto-optical devices.

Contribution

It provides new insights into the role of geometrical symmetries in coupled acoustoplasmonic resonators, highlighting how symmetry breaking affects mode coupling and introduces novel resonant modes.

Findings

Broken mirror symmetries couple nanomechanical modes.

Symmetry breaking introduces new torsional resonant modes.

Optical and mechanical responses are affected differently by symmetry.

Abstract

Acoustoplasmonic resonators, such as nanobars and crosses, are efficient acousto-optical transducers. The excitation of mechanical modes in these structures strongly depends on the spatial profile of the eigenmodes of the resonator. Using a system of two identical gold elongated bars placed on a silicon dioxide substrate, we examine how breaking mirror symmetries affects the optical and acoustic properties to provide insights in the design of acoustoplasmonic metasurfaces for nonsymmetric acousto-optical transducers. Our findings show that, the absence of mirror symmetries affects differently the optical and nanomechanical response. Broken mirror symmetries not only couple nanomechanical modes existing in single bars, but introduces new torsional resonant modes.