Single-beam triaxial spin-exchange relaxation-free atomic magnetometer utilizing transverse modulation fields

Abstract

Abstract We display a single-beam triaxial spin-exchange relaxation-free (SERF) atomic magnetometer by utilizing two orthogonal transverse modulation fields perpendicular to the light. The magnetic field’s three-axis vector components can be extracted simultaneously and independently from the transmitted light by lock-in amplifiers with reference to the different demodulated frequencies. We find that the residual magnetic field is a significant factor that could affect triaxial coupling, and specially the influence of the z-axis remanence on xy-axis coupling is studied in detail. Under the optimal parameters, the three-axis sensitivities are 20 fT Hz − 1 / 2 in the x- and y- axis, and 230 fT Hz − 1 / 2 in the z-axis. Meanwhile, the three-axis bandwidths are 110 Hz, 138 Hz and 211 Hz in the x-, y- and z-axis, respectively. The proposed single-beam triaxial SERF atomic magnetometer could be used to construct a compact and low-cost atomic sensor that is particularly suitable for the vector measurement of the biomagnetic such as magnetoencephalography and magnetocardiography.