基于以小型化磁控管微波腔实现的脉冲光抽运铷原子钟, 研究了自由演化时间对Ramsey信号特性的影响, 讨论了横向弛豫时间对钟信号对比度的影响.该原子钟的自由演化时间为3 ms时, Ramsey信号中心条纹的对比度为52%, 散弹噪声极限优于1.7×10－14(τ=1 s).利用Ramsey信号的对比度和吸收泡内的光密度, 计算得到了原子钟内铷吸收泡的纵向和横向弛豫时间分别为1.95 ms和 2.45 ms.本文研究为进一步提高脉冲光抽运铷原子钟的性能提供了重要依据.

The influence of free evolution time on the Ramsey signal characteristics of a pulsed optically pumped Rb clock based on a compact magnetron microwave cavity was reported, and in addition, the effect of coherence relaxation time on the contrast of clock signal was discussed. When the optimal free evolution time of the atomic clock is about 3 ms, the Ramsey central fringe contrast is as high as 52% and the shot-noise-limit is better than 1.7×10－14(τ=1 s). According to the contrast of the Ramsey signal and the optical density in the vapor cell, both population and coherence relaxation times of Rb vapor cell in the atomic clock are 1.95 ms and 2.45 ms, respectively. The experiment provides a useful basis for improving the performance of the pulsed optically pumped Rb clock.