Signal enhancement in single-beam free-induction-decay magnetometers by manipulation of spin polarization

The conventional single-beam free-induction-decay (FID) magnetometers based on an optical modulation scheme suffer from the reduction of signal in non-orthogonal magnetic field orientations, leading to worse magnetometer sensitivity. Here, we propose a scheme to enhance the signal in single-beam FID magnetometers by manipulation of spin polarization. The spin polarization built up by synchronous optical pumping is rotated to fully undergo free precession under the manipulation of the RF pulse field. We theoretically and experimentally validate the effectiveness of the proposed scheme, demonstrating that it achieves the enhancement of the FID signal in non-orthogonal magnetic field orientations and improves the magnetometer sensitivity. The scheme described in this work provides what we believe to be a new pathway to improve the magnetometer performance in various applications.