Optical Rotation Detection Method Based On Acousto-Optic Modulation In An Atomic Spin Co-Magnetometer

A new concept for probe light intensity stability control and high-frequency modulation based on an acousto-optic modulation in a K-Rb-Ne-21 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 7.9x10(-7)rads(-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.