用于铯原子磁力仪的双AOM激光稳频系统

The basic working principle of the atomic magnetometer is to polarize the atom by optical pumping. The magnetic field is probed by detecting the Larmor precession of spin polarization. The pumping laser that is used to polarize the atom plays an important role in magnetic field detection. Due to the influence of environment, the frequency of free running laser shifts with time, which reduces the sensitivity of atomic magnetometer. In this paper, the relationship between the output of Bell-Bloom magnetometer and the frequency fluctuation of pump light is theoretically deduced. Then, a differential detection method is proposed, which is based on the double AOM frequency shift. In this way, the frequency stabilization of the system can be realized. The automatic frequency locking algorithm is designed and evaluated by experiments. Results show that the system can be stabilized at the working zero point. The RMS of frequency jitter before frequency stabilization is about 28.02 MHz. After dual AOM frequency stabilization, the RMS of laser frequency jitter is reduced to 0.12 MHz. The closed-loop equivalent output noise of atomic magnetometer is 0.012 pT, which can provide a reference in the design of a high precision magnetometer.