Enhancement of Electron-Spin Polarization Using Magneto-Optical Synchronous Modulation

Resonance-based optically pumped magnetometers have been widely used in various fields of magnetic field measurement. The electron-spin polarization affects the magnetometer response, which directly determines the signal-to-noise ratio and sensitivity performance of the magnetometer. The usual way to increase electron-spin polarization is to increase the pumping light power, which also causes the optical broadening of resonance linewidth. In this work, we propose a novel method of magneto-optical synchronous modulation to enhance the electron-spin polarization without introducing additional optical broadening, which can enhance the response and reduce the dead zone of traditional resonance-based magnetometers. This method excites atomic resonance by the modulated transverse magnetic field and longitudinal pumping light with Larmor frequency. The theoretical model of magneto-optical synchronous modulation magnetometer is established and verified experimentally. Compared with single magnetic field modulation and single optical field modulation, the magneto-optical synchronous modulation method improves the magnetometer response signal, which is directly related to the sensitivity performance of magnetometers. Moreover, this method reduces the measurement dead zone to a plane compared to conventional magnetic field resonance magnetometers.