Optomechanical technologies for broadband inertial sensing

Abstract

Accelerometers are a vital component in inertial sensing and geodesy, gravitational physics, seismic noise detection, hydrology, and other fields requiring precision measurements. Our group develops compact low and high frequency optomechanical inertial sensors to measure acceleration for various applications. Our sensors measure the linear displacement of an oscillating test mass with displacement laser interferometers that are fiber-coupled or free space. The observed external acceleration is recovered from the displacement of the test mass. Our compact 5 Hz resonator will operate as a relative gravimeter and be read out by a compact, highly sensitive free-space heterodyne laser interferometer. It has demonstrated low mechanical losses with quality factors above 4.77 × 105 and mQ-products greater than 1200 kg. Our millimeter scale higher frequency resonators are made of fused silica for operation at room temperature and Si for operation at cryogenic temperatures. They will be readout with fiber based Fabry-Perot cavities or waveguide ring resonators that are currently under development. We are working to fabricate the Si resonators and are optimizing the process using Bosch and cryo-Si DRIE etching. Here, we report our progress on design and fabrication along with preliminary measurement results for all resonator prototypes. Copyright © 2022 SPIE.