WANG Xin1,2，FAN Qi1,3，DU Zhi-jing1，GUO Wen-ge1，CHANG Hong1，ZHANG Shou-gang1

（1. National Time Service Center, Chinese Academy of Sciences, Xi’an, Shaanxi 710600, China；

2. Graduate University of Chinese Academy of Sciences, Beijing 100039, China；

3. school of Science, Air Force Engineering University, Xi’an, Shaanxi 710051, China）

Abstract：Based on the model of the L-type three-level atomic system, the impact of laser parameters on the CPT signals of rubidium atomic clock isanalyzed by using the semi-classical density matrices approach in order to make a concrete analysis of the influence of laser parameters upon the stability performance of the CPT（coherent population trapping）atomic clock, and the comparison is presented. The results show that the signal intensity of the CPT clock significantly varies with the intensity symmetry of the laser beams. In contrast, the influence of the frequency detuning is not important for the clock signal. In addition, when the laser intensity asymmetry and frequency detuning exist together, the asymmetry of the CPT fluorescence spectrum and the frequency shift of the CPT microware signal would occur.

Key words：coherent population trapping；atomic clock；L-type three-level atomic system