Analysis and Optimization of Probe Laser Power Density Based on the SNR Model for a K–Rb– ²¹ Ne Comagnetometer

ABSTRACT The sensitivity and long‐term stability of the K–Rb– comagnetometer are significantly influenced by the signal‐to‐noise ratio (SNR) of the laser detection system. For the first time, this article establishes a quantitative relationship between probe laser power density (PLPD) and the output signal, while also providing a systematic classification of noise sources contributing to the detection signal. Based on this analysis, an SNR model for the comagnetometer's output is developed, and a method to enhance the performance of the K–Rb– comagnetometer through PLPD optimization is proposed. Experimental results demonstrate that increasing the probe laser beam diameter enhances the scale factor by more than threefold compared to the conventional 1 mm beam diameter. At the optimal PLPD point, the comagnetometer's SNR at 1 Hz improved by 32 % compared to the pre‐optimization state. The probe background sensitivity and stability increased by 43 % and 41 %, respectively, while the output signal sensitivity and stability improved by 28 % and 27 %. Furthermore, the SNR enhancement method proposed in this paper also shows potential for application in other atomic sensors, such as SERF magnetometers and nuclear magnetic resonance gyroscopes.