Three-axis magnetic field measurement based on dual-pump polarization with high sensitivity and orthogonality

An optically pumped magnetometer (OPM) for three-axis magnetic field measurement is demonstrated based on dual-pump polarization in a time-sharing regime. By detecting light absorption, each pump beam can achieve high-sensitive transverse measurement under modulation magnetic fields around a near-zero field. After the combination and orthogonalization of two pumps according to the scale factors along the reference axis, a three-axis orthogonal measurement system is obtained. Compared with existing methods, this configuration reduces misalignment errors introduced by the nonorthogonality of the sensitive directions and avoid coupling errors introduced by cross-axis DC magnetic fields. The coupling among the three axes is below 0.39%. On this basis, this OPM performs equivalent performances of each axis measurement with high accuracy and realizes a high sensitivity of 10 fT/Hz^1/2. This SERF OPM can be employed in wide variety of applications including biological magnetic detection and sensitive tests of fundamental physics.