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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mi/> <mml:mrow> <mml:mo>−</mml:mo> <mml:mrow> <mml:mn>1</mml:mn> <mml:mrow> <mml:mo>/</mml:mo> </mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:mrow> </mml:msup> </mml:math> in the x - and y - axis, and 230 fT Hz <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mi/> <mml:mrow> <mml:mo>−</mml:mo> <mml:mrow> <mml:mn>1</mml:mn> <mml:mrow> <mml:mo>/</mml:mo> </mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:mrow> </mml:msup> </mml:math> 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.