# Mechano-mechanical parametric coupling in MEMS between GHz and kHz frequency regimes at room temperature

## TL;DR

This paper introduces a new MEMS system that uses mechanical coupling between GHz and kHz frequencies to improve sensor performance and reduce noise.

## Contribution

The novel contribution is a purely mechanical parametric coupling system using GHz surface acoustic waves and kHz cantilevers at room temperature.

## Key findings

- Red and blue sidebands in the frequency spectrum confirm energy exchange between GHz SAW and kHz cantilever.
- Calculated coupling strength g0 is on the order of 10−3 Hz, comparable to optomechanical systems.
- Mechano-mechanical coupling is shown to be a viable alternative to optomechanical interactions in MEMS.

## Abstract

Microelectromechanical systems (MEMS) sensors have been widely used in various fields, but their performance is often limited by thermal fluctuations and detection noise. Inspired by advances in cavity optomechanics, which utilize parametric coupling for precision sensing and noise reduction, we explore a new approach to overcoming these limitations. We demonstrate a purely mechanical parametric coupling system that replaces the optical mode with a GHz surface acoustic wave (SAW) cavity. This system couples the GHz SAW cavity with a kHz micro-cantilever oscillator under ambient conditions, bridging vastly different frequency regimes within a unified framework. This mechano-mechanical coupling is experimentally demonstrated by the generation of red and blue sidebands in the frequency spectrum as direct evidence of energy exchange between the SAW cavity and multiple vibrational modes of the cantilever. Using the standard cavity optomechanics framework, we calculate the coupling strength g0, which is on the order of 10−3 Hz, and compare it with previously reported values in optomechanical and electromechanical systems. Our findings establish mechano-mechanical parametric coupling as a practical alternative to conventional optomechanical interactions, offering a new framework for integrating GHz and kHz mechanical resonators into silicon MEMS-compatible platforms.