Impact analysis of cavity length on transfer cavity frequency locking system for atomic inertial measurement device

In this work, an efficient method for frequency stabilization of a highly off-resonant laser in a spin-exchange relaxation-free atomic inertial sensor is proposed. This was accomplished via the use of an optical resonator that transferred the stability of an atomic energy level to the laser frequency. The pump laser frequency was stabilized via saturation absorption spectroscopy and was used as a reference to lock the large-detuned probe laser with a double transmission Fabry-Pérot (FP) cavity. The frequency stability and bandwidth of the entire transfer cavity frequency locking system were investigated, and the results were used to elucidate the effect of cavity length on stability. The frequency stability of the system approached 1.66 × 10^-11 when the FP cavity length was 30 mm. This method can be applied to a variety of ultrasensitive atomic physics experiments, such as for precision spectroscopy and laser cooling.