Suppression Method of Light Shift in K-Rb Hybrid Optical Pumping SERF Atomic Comagnetometer

The light shift generated by the circularly polarized light leads to an error in the spin-exchange relaxation-free (SERF) comagnetometer, since it turns the fluctuations of the pumping light frequency and intensity into a drift in the SERF comagnetometer. Moreover, the light shift is a source of cross-talk effect between the two sensitive axes. Firstly, the relationship between the vapor cell temperature and the total light shift felt by Rb atoms in the K-Rb hybrid pumping SERF comagnetometer is formulated and simulated. It is found that the total light shift is the result of the collision mixing of K and Rb ac Stark shifts and the increase of cell temperature makes the light shift of K felt by Rb dominate the total light shift. Furthermore, different from the method of adjusting the frequency of laser, a new method that suppresses the total light shift in hybrid pumping by adjusting the cell temperature is proposed and experimentally verified. The total light shift at 165.7°C is -0.00152 nT experimentally, which is 3 orders of magnitude smaller than that at 185.0°C, indicating that it can be suppressed effectively by adjusting the cell temperature. The method does not require any extra hardware or sacrifice the pumping efficiency and can be applied to suppress the error induced by the pumping light and the cross-talk effect between the axes. In addition, the relationship between total relaxation rate and cell temperature is briefly discussed.