Pulsed-Modulation Single-Beam Three-Axis Atomic Magnetometer

The three-axis spin-exchange relaxation-free (SERF) atomic magnetometer (AM) enables full-vector magnetic field measurements with high sensitivity, offering significant potential for improving the accuracy of magnetic source reconstruction. However, most existing three-axis schemes rely on multiple continuous high-frequency modulation fields, which reintroduce spin-exchange relaxation and induce interaxis crosstalk. Here, we propose a three-axis magnetic field measurement method based on pulsed magnetic field modulation. By applying a transverse rotating pulsed field and a longitudinal pulsed field, the three-axis components of the vector magnetic field can be extracted from the longitudinal transmitted optical signal. The pulsed magnetic field reduces the continuous interaction time of the modulation field via its duty cycle, thereby suppressing spin-exchange relaxation. The designed synchronized time-division three-axis pulsed fields avoid the coupling effect of multiaxis modulation on spin polarization in the overlap region, thus effectively minimizing interaxis crosstalk while enabling real-time three-axis measurement. Experimental results demonstrate that the proposed method reduces the modulation-induced spin-exchange relaxation rate by approximately 40 %, achieving transverse dual-axis sensitivity of 13 fT/Hz¹/² for the x- and yaxes, and a longitudinal sensitivity of 70 fT/Hz¹/² for the z-axis in a 4 × 4 × 4 mm^{3 87}Rb vapor cell. The interaxis crosstalk is suppressed to less than 1 % over the 1–100-Hz bandwidth. The proposed scheme provides new insights for constructing compact and low-cost single-beam three-axis SERF AMs.