Picotesla-sensitivity microcavity optomechanical magnetometry

作者：Zhigang Hu, Yimeng Gao, Jianfei Liu, Hao Yang, Min Wang, Yuechen Lei, Xin Zhou, Jincheng Li, Xuening Cao, Jinjing Liang, Chaoqun Hu, Zhilin Li, Yong‐Chang Lau, Jian-Wang Cai, Beibei Li · 发表于：Light Science & Applications · 年份：2024 · DOI：10.1038/s41377-024-01643-7 · 被引用次数：39 · 研究领域：Mechanical and Optical Resonators、Advanced MEMS and NEMS Technologies、Magneto-Optical Properties and Applications

Abstract Cavity optomechanical systems have enabled precision sensing of magnetic fields, by leveraging the optical resonance-enhanced readout and mechanical resonance-enhanced response. Previous studies have successfully achieved mass-produced and reproducible microcavity optomechanical magnetometry (MCOM) by incorporating Terfenol-D thin films into high-quality ( Q ) factor whispering gallery mode (WGM) microcavities. However, the sensitivity was limited to 585 pT Hz −1/2 , over 20 times inferior to those using Terfenol-D particles. In this work, we propose and demonstrate a high-sensitivity and mass-produced MCOM approach by sputtering a FeGaB thin film onto a high- Q SiO 2 WGM microdisk. Theoretical studies are conducted to explore the magnetic actuation constant and noise-limited sensitivity by varying the parameters of the FeGaB film and SiO 2 microdisk. Multiple magnetometers with different radii are fabricated and characterized. By utilizing a microdisk with a radius of 355 μm and a thickness of 1 μm, along with a FeGaB film with a radius of 330 μm and a thickness of 1.3 μm, we have achieved a remarkable peak sensitivity of 1.68 pT Hz −1/2 at 9.52 MHz. This represents a significant improvement of over two orders of magnitude compared with previous studies employing sputtered Terfenol-D film. Notably, the magnetometer operates without a bias magnetic field, thanks to the remarkable soft magnetic properties of the FeGaB film. Furthermore, as a proof of concept, we have ...