Optomechanical crystal with bound states in the continuum

TL;DR

This paper introduces a new type of 2D optomechanical crystal featuring bound states in the continuum at 8 GHz, enabling strong photon-phonon interactions for advanced sensing and quantum applications.

Contribution

It demonstrates symmetry-induced bound states in the continuum in 2D optomechanical crystals with high optomechanical coupling, expanding the platform beyond suspended microcavities.

Findings

Achieved optomechanical coupling up to 2.5 MHz per unit cell.

Realized symmetry-induced bound states in the continuum at 8 GHz.

Enabled strong photon-phonon interactions in a chip-scale device.

Abstract

Chipscale micro- and nano-optomechanical systems, hinging on the intangible radiation-pressure force, have shown their unique strength in sensing, signal transduction, and exploration of quantum physics with mechanical resonators. Optomechanical crystals, as one of the leading device platforms, enable simultaneous molding of the band structure of optical photons and microwave phonons with strong optomechanical coupling. Here, we demonstrate a new breed of optomechanical crystals in two-dimensional slab-on-substrate structures empowered by mechanical bound states in the continuum (BICs) at 8 GHz. We show symmetry-induced BIC emergence with optomechanical couplings up to $g/2\pi\approx 2.5$ MHz per unit cell, on par with low-dimensional optomechanical crystals. Our work paves the way towards exploration of photon-phonon interaction beyond suspended microcavities, which might lead to new applications of optomechanics from phonon sensing to quantum transduction.