Suppression of Bias Instability Induced by Fluctuations in Pump Light Power Density by Vapor Cell Temperature Optimization in Spin-Exchange Relaxation-Free Co-Magnetometers

Bias instability is one of the most critical factors in the performance of a spin-exchange relaxation-free (SERF) co-magnetometer. Previous studies on the SERF co-magnetometer have shown that fluctuations in pump light power density cause variations in the pumping rate, which in turn affect the system’s bias instability. Building on this, this article analyzes the steady-state response errors in the SERF co-magnetometer caused by fluctuations in pump light power density. By adjusting the vapor cell temperature, the SERF co-magnetometer can be tuned to a vapor cell operating point where the output signal is insensitive to fluctuations in pump light power density, referred to as the pump light power density fluctuation insensitive point. This effectively suppresses the bias instability caused by fluctuations in pump light power density. The proposed method was experimentally validated, and the results showed good consistency with the model. Using this method, the SERF co-magnetometer can achieve insensitivity to pump light power density fluctuations at a specific operating temperature without the need to adjust the laser wavelength or add additional hardware. This effectively reduces the impact of pump light power density fluctuation on bias instability of the SERF co-magnetometer. This study proposes a method to enhance the performance of the SERF co-magnetometer, providing valuable reference for quantitative error analysis and practical engineering applications.