Brillouin Optomechanics in Coupled Silicon Microcavities

TL;DR

This paper demonstrates the engineering of coupled silicon microcavities to achieve low-threshold excitation of high-frequency mechanical modes via backward stimulated Brillouin scattering, advancing integrated optomechanical systems.

Contribution

It introduces microcavity designs supporting ultra-high frequency modes and large optomechanical coupling rates for Brillouin optomechanics in silicon microcavities.

Findings

Achieved mechanical modes at ~25 GHz frequency.

Realized large optomechanical coupling rates (~50 kHz).

Enabled low-threshold excitation of mechanical waves.

Abstract

The simultaneous control of optical and mechanical waves has enabled a range of fundamental and technological breakthroughs, from the demonstration of ultra-stable frequency reference devices to the exploration of the quantum-classical boundaries in laser-cooling experiments. More recently, such an opto-mechanical interaction has been observed in integrated nano-waveguides and microcavities in the Brillouin regime, where short-wavelength mechanical modes scatters light at several GHz. Here we engineer coupled optical microcavities spectra to enable a low threshold excitation of mechanical travelling-wave modes through backward stimulated Brillouin scattering. Exploring the backward scattering we propose microcavity designs supporting super high frequency modes ($\sim25$ GHz) an large optomechanical coupling rates ($g_0/2\pi \sim 50$ kHz).