All-optical dual-axis zero-field atomic magnetometer using light-shift modulation

Abstract

Functional imaging equipment based on miniaturized atomic magnetometers with array arrangement exhibits promising prospects in biomagnetic scenarios. However, crosstalk from the modulated magnetic field between adjacent sensors degrades the imaging accuracy. To address this issue, this study proposes an all-optical dual-axis zero-field atomic magnetometer using light-shift modulation. We utilize an acousto-optic modulator to modulate a detuned circularly polarized beam for pumping the atomic spin ensembles. This beam allows for the optical modulation of spin polarization and meanwhile generates a light-shift modulation, effectively replacing the conventional magnetic field modulation. By using a probe beam to detect the optical rotation angle perpendicular to the direction of the pump beam, we construct an all-optical configuration of a longitudinally modulated atomic magnetometer, enabling dual-axis magnetic field measurements. Experimental results demonstrate dual-axis sensitivities of 29 and $15\mathrm{fT}/{\mathrm{Hz}}^{1/2}$, respectively. This method eliminates the need for conventional coil-based magnetic field modulation, thereby paving the way for potential applications in magnetocardiography and magnetoencephalography.