Study on the low frequency magnetic detection sensitivity of cavity optomechanical magnetometer

The whispering gallery mode ( WGM ) microcavity is a widely used microresonator. With its ultra-high quality factor Q ( above 109 ) and small mode volume ( µm3 ) , it can amplify the interaction between substances. The giant magnetostrictive material Terfenol-D is a rare earth material that can respond to changes in the magnetic field. With its ultra-high magnetostrictive coefficient ( 1500∼2000 ppm ), ultra-fast response speed( less than 1 µs ), and efficient energy conversion efficiency ( about 50% ), it is widely used in magnetic field sensors. Therefore, a high-sensitivity cavity optomechanical magnetometer can be designed and manufactured by combining the WGM and Terfenol-D. By analyzing the inherent characteristic frequency and magnetostrictive material characteristics of the cavity optomechanical magnetometer, the sensitivity of the magnetometer in magnetic field detection is greatly improved by mixing the bias magnetic field with the excitation magnetic field. In our simulation, compared with the environment without bias magnetic field, the deformation of the cavity optomechanical magnetometer is about 106 times higher of the original after adding the bias magnetic field, which will greatly enhance the detection sensitivity of the excitation magnetic field and provide an effective method for detecting biomagnetic signals.