A miniaturized high-sensitivity single-beam triaxial SERF atomic magnetometer

The triaxial vector optically pumped magnetometers represent an important class of sensors for biomagnetic imaging. This paper proposes a miniaturized, high-sensitivity single-beam triaxial SERF atomic magnetometer with the size of 19 mm×18 mm×14 mm based on optical fiber transmission. This compact scheme utilizes the designed beam splitting prism to divide a beam of light into two spatially separated circularly polarized pump beams equally that pass through a same vapor cell, so that the magnetometer achieves synchronous measurement of three-axis magnetic fields without sacrificing the sensitivity of each axis. We also develop an approximate analytical model of the electron spin polarization dynamics under triaxial modulation field. Through theoretical simulation and experimental research, the influence of the modulated field on the triaxial dispersion response is verified. At the optimal modulation parameter, the magnetometer achieves sensitivities of 15.0fT/Hz^1/2, 14.6fT/Hz^1/2 and 16.5fT/Hz^1/2 on the x, y and z axes respectively in the frequency range of 3∼100 Hz. This triaxial magnetometer with small size, strong stability and high sensitivity enables precise spatial field mapping for biomedical imaging, including magnetocardiography and magnetoencephalography.