Research and suppression of optical pointing noise in SERF magnetometers

In the development of Spin-Exchange Relaxation-Free (SERF) magnetometers, the magnetic field measurement signal is affected by beam pointing fluctuations, which limit the further improvement of sensitivity. In order to minimize pointing noise, we propose a SERF magnetometer response model that explicitly incorporates the effect of beam-pointing angle. The model describes how pointing fluctuations modify light-atom interactions and subsequently impact optical detection. To suppress pointing noise, we further propose an integrated mitigation scheme that combines mode cleaner (MC) with a dual acousto-optic modulator (AOM) configuration. MC reduce beam pointing fluctuations through spatial filtering, dual AOMs suppresses intensity noise through intensity modulation, and a 3-level cascade structure achieves suppression of pointing noise and intensity noise. This method enhances the optimal sensitivity of magnetic field measurement by 38.7% (at 20 Hz), while simultaneously reducing pointing noise and other noise sources, including intensity noise. The pointing noise suppression promote SERF magnetometers towards lower noise and higher precision quantum measurements.