Acoustic confinement in superlattice cavities

TL;DR

This paper introduces a mathematical scattering matrix model to predict acoustic modes in GaAs/AlAs superlattice cavities, revealing enhanced confinement, high quality factors, and novel Fano resonances for optomechanical use.

Contribution

The study presents a new scattering matrix model for acoustic mode prediction in superlattice cavities, highlighting the impact of surface reflection and discovering high-Q Fano resonances.

Findings

Reflection at surface boundary enhances acoustic confinement.

Predicted high mechanical quality factors in nanopillars.

Unprecedented acoustic Fano resonances with small mode volumes.

Abstract

The large coupling rate between the acoustic and optical fields confined in GaAs/AlAs superlattice cavities makes them appealing systems for cavity optomechanics. We have developed a mathematical model based on the scattering matrix that allows the acoustic guided modes to be predicted in nano and micropillar superlattice cavities. We demonstrate here that the reflection at the surface boundary considerably modifies the acoustic quality factor and leads to significant confinement at the micropillar center. Our mathematical model also predicts unprecedented acoustic Fano resonances on nanopillars featuring small mode volumes and very high mechanical quality factors, making them attractive systems for optomechanical applications.