The optimization and stabilization of detuned probe light frequency to suppress electron spin polarization error in SERF co-magnetometer

Abstract

Spin-exchange free-relaxation (SERF) co-magnetometer has promising applications in the field of inertial navigation and fundamental physics experiments since its coupled spin ensemble is capable of measuring rotation with ultra-high sensitivity. Electron spin polarization determines the performance of the SERF co-magnetometer directly. In this paper, it is found that there is a non-negligible coupling between the probe light frequency and electron spin polarization. A model of the polarization in relation to the probe light frequency for a hybrid pumping cell is established. This paper discovers the existence of a theoretical optimum frequency that enables a more stable polarization in the model, and an experimental verification is carried out. Experiments results show that when the SERF co-magnetometer operates at this optimization frequency, its short- and long-term stability is significantly enhanced. Further, based on this model, the detuned frequency stabilization technique is proposed. The long-term stability of the probe light frequency is also improved by 43.85% after closing the loop.