# Phonon-laser sensing in a hetero optomechanical crystal cavity

## TL;DR

This paper demonstrates a silicon hetero optomechanical crystal cavity that supports phonon lasing, significantly enhancing on-chip sensing resolution and paving the way for high-precision, integrable sensors for various physical properties.

## Contribution

Introduction of a silicon hetero optomechanical crystal cavity supporting phonon lasing with high optomechanical coupling and narrow linewidth, improving sensing resolution.

## Key findings

- Achieved phonon lasing at 5.91 GHz in a silicon nanobeam cavity.
- Enhanced sensing resolution to 1.0×10⁻⁸, surpassing conventional sensors.
- Narrowed mechanical linewidth from 3.3 MHz to 5.2 kHz.

## Abstract

Micro- and nanomechanical resonators have emerged as promising platforms for sensing a broad range of physical properties such as mass, force, torque, magnetic field, and acceleration. The sensing performance relies critically on the motional mass, the mechanical frequency, and the linewidth of the mechanical resonator. Here, we demonstrate a hetero optomechanical crystal (OMC) cavity based on a silicon nanobeam structure. The cavity supports phonon lasing in a fundamental mechanical mode with a frequency of 5.91 GHz, an effective mass of 116 fg, and a mechanical linewidth narrowing from 3.3 MHz to 5.2 kHz, while the optomechanical coupling rate of is as high as 1.9 MHz. With this phonon laser, the on-chip sensing with a resolution of $\delta$$\lambda$/$\lambda$ = 1.0*10-8 can be attained, which is at least two orders of magnitude larger than that obtained with conventional silicon-based sensors. The use of a silicon-based hetero OMC cavity that harnesses phonon lasing could pave the way towards exciting, high-precision sensors that lend themselves to silicon monolithic integration and offer unprecedented sensitivity for broad physical sensing applications.

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Source: https://tomesphere.com/paper/1906.12057