A high sensitivity and strong stability miniaturized optically-pumped magnetometer

In this paper, we focus on the phase noise in optically-pumped magnetometer systems and investigate its sources, and use dual-phase lock-in technique to solve the problem. The results show that the phase noise is maximum when the system operates under zero-magnetic-field condition, and the main source comes from the environment stray magnetic field. The dual-phase lock-in technique improves the phase noise rejection by a factor of 10 compared to the single-phase lock-in technique. The sensitivity of the system is 22 fT Hz−1/2 and the bandwidth is 158 Hz, which offers a favorable outlook for use in clinical settings.