Optomechanical Magnetometry on a Bubble Resonator With YIG Microsphere

Magnetometry sensors have wide applications across science and technology. A magnetometer at room temperature can be made by coupling a magnetostrictive material to a high-Q optical cavity, which is crucial for achieving the high sensitivity in detecting the magnetic field. In this work, we have designed a hybrid structure based on the high-Q optical capillary microresonator filled with a yttrium iron garnet (YIG) microsphere to realize highly sensitive magnetic field sensing in the range of kHz. The device shows a peak magnetic field sensitivity of 146 pT Hz $^{-1/2}$ at frequency of 16.85 kHz. This sensor structure provides high sensitivity in the range of 9 kHz to 100 kHz, thus allowing applications in magnetic anomaly detection and other fields.