Fig. 1. Schematic of the three-axis atomic magnetometer developed with two elliptically polarized lights.

Fig. 2. Schematic of the closed-loop control system.

Fig. 3. Setup of the three-axis SERF magnetometer. PMF, polarization-maintaining fiber; CL, collimating lens; QWP, quarter-wave plate; HWP, half-wave plate; PD, photodiode; TIA, trans-impedance amplifier; LIA, lock-in amplifier.

Fig. 4. The scale factor of the atomic magnetometer under different laser detunings and intensities.

Fig. 5. The scale factor of the atomic magnetometer with a modulation frequency of 1 kHz under different amplitudes of the modulation field.

Fig. 6. The single-axis sensitivity of the magnetometer along the y axis.

Fig. 7. The sensitivity of the three-axis atomic magnetometer. The average sensitivity is 14 fT/Hz^1/2 along the x axis, 11 fT/Hz^1/2 along the y axis, and 25 fT/Hz^1/2 along the z axis.

Fig. 8. The bandwidth of the three-axis magnetometer operated under different regimes. (a) The three-axis bandwidth is about 150, 90, and 180 Hz along the x, y, and z axes, respectively, under the open-loop regime. (b) The measurement bandwidth is 240, 200, and 280 Hz along the three orthogonal axes under the closed-loop regime.

Fig. 9. The response of the three-axis magnetometer with respect to the three-axis magnetic field under the condition of the closed-loop control. The response signals for different magnitudes of the input magnetic field along the (a) x, (b) y, and (c) z axes are measured.