The influence of polarization misalignment for modulation transfer spectrum in atom gravimeter

The accuracy of atom gravimeters is directly related to the Raman laser, which is used to manipulate the atomic wave packet, and the frequency of the Raman laser could be affected by temperature when the laser polarization is not along the preferred axis of the electro-optic crystal employed in the modulation transfer spectrum (MTS). This effect has been researched by modulating the laser polarization in the MTS in this work. The experimental results show that both the laser frequency and gravity measurement results have a sinusoidal dependence on temperature, and the period of the fluctuation is 0.8 °C. The systematic effect can reach 12.4 μGal when the polarization misalignment is 15°, which is a remarkable contribution to the absolute gravity measurement. The amplitude of this effect could be reduced by adjusting the laser polarization to the crystal's preferred axis. According to the result, the included angle between the laser polarization and the crystal's preferred axis should be smaller than 5° if 2 μGal accuracy is required.