Response-Enhanced Over-Polarization Measurement for SERF Magnetometer Based on Pump Beam Modulation

Conventional methods for enhancing the response of spin-exchange relaxation-free (SERF) magnetometers primarily focus on optimization of the cell working state but remain constrained by the limited equilibrium polarization. To overcome this limitation, we proposed a response-enhanced over-polarization measurement method for SERF magnetometer based on pump beam modulation, which allows the polarization and measurement processes to be independent. We established the theoretical model of the transverse polarization during the transient response after the pump beam is altered off. Then we verified the validity of our method under different modulation frequencies and duty cycles and proposed the parameter selection criteria to meet the acquirements of our over-polarization measurement mode. Compared to the traditional dc-mode, numerical simulation and experiment have both demonstrated that the response can be enhanced by 47% and 43%, respectively, which is consistent with our theoretical analysis. Moreover, this method inherently mitigates the light-shift effect and facilitates high polarization uniformity across the vapor cell. These findings, supported by comprehensive sensitivity analysis and robustness evaluation, demonstrate the method’s potential for practical applications in high-sensitivity magnetometry, such as biomagnetic imaging and anomaly detection.