Optical rotation detection method based on acousto-optic modulation in an atomic spin co-magnetometer

Abstract

A new concept for probe light intensity stability control and high-frequency modulation based on an acousto-optic modulation in a K-Rb-21Ne co-magnetometer is reported. The structure and optical path are ingeniously designed to avoid the interference of zero-order diffraction light. The average rotation rate sensitivity of 7 .9 × 1 0 - 7 rad s − 1 Hz − 1 / 2 is achieved under the light intensity closed-loop control condition and the bias instability calculated by the Allan deviation is improved from 0.13 deg h−1 to 0.06 deg h−1 comparing with open-loop scheme. A square wave modulation with a wide range of frequencies is applied to the probe light intensity and the appropriate modulation frequency for the co-magnetometer is tested to be 10 kHz to 300 kHz and megahertz scale. Finally, the closed-loop control of light intensity has been combined with the high-frequency modulation, which could suppress the low-frequency noise contained in the probe system and improve the long-term stability of the angular velocity measurement.

Probe beam influence on spin polarization in spin-exchange relaxation-free co-magnetometers

“…In SERF co-magnetometers, atomic spin ensembles are polarized by the pump beam while the atomic spin precession signal is obtained by the probe beam [10]. In previous studies, the probe beam has always simply been regarded as a problem related to the scale factor, and it is considered to be ideally linearly polarized without interference with the spin polarization [11]. However, as studies progressed the nonlinear relationship between the probe power density and the stability of the SERF co-magnetometer suggested that the effect of the probe beam on spin polarization needed to be analyzed.…”