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 SiO₂ 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 SiO₂ 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 demonstrated the real-time measurement of a pulsed magnetic field simulating the corona current in a high-voltage transmission line using our developed magnetometer. These high-sensitivity magnetometers hold great potential for various applications, such as magnetic induction tomography and corona current monitoring.

腔体光机械系统通过利用光学共振增强读出和机械共振增强响应，实现了对磁场的精确传感。以前的研究通过将 Terfenol-D 薄膜掺入高质量 （Q） 因子耳语画廊模式 （WGM） 微腔中，成功地实现了大规模生产和可重复的微腔光机械磁力测量 （MCOM）。然而，灵敏度仅限于 585 pT ^Hz-1/2，比使用 Terfenol-D 颗粒的灵敏度低 20 倍以上。在这项工作中，我们提出并演示了一种通过将 FeGaB 薄膜溅射到高 Q 值 SiO₂ WGM 微盘上的高灵敏度和批量生产的 MCOM 方法。通过改变 FeGaB 薄膜和 SiO₂ 微盘的参数，进行了理论研究，探究了磁驱动常数和噪声限制灵敏度。制造了多个具有不同半径的磁力计并进行了表征。通过使用半径为 355 μm、厚度为 1 μm 的微盘，以及半径为 330 μm 和厚度为 1.3 μm 的 FeGaB 薄膜，我们在 9.52 MHz 时实现了 1.68 pT ^Hz-1/2 的显着峰值灵敏度。与之前采用溅射 Terfenol-D 薄膜的研究相比，这代表了超过两个数量级的显着改进。值得注意的是，由于 FeGaB 薄膜具有卓越的软磁特性，磁力计在没有偏置磁场的情况下工作。此外，作为概念验证，我们已经演示了使用我们开发的磁力计模拟高压输电线路中电晕电流的脉冲磁场的实时测量。 这些高灵敏度磁力计在各种应用中具有巨大潜力，例如磁感应断层扫描和电晕电流监测。