光抽运小铯钟光频移评估与抑制方法研究  

Research on evaluation and suppression methods of light shifts of optically pumped cesium beam frequency standard

作　　者：韦强 WEI Qiang(Chengdu Spaceon Electronics Company Limited,Chengdu 610036,China)

机构地区：[1]成都天奥电子股份有限公司,成都610036

出　　处：《时间频率学报》2024年第2期73-80,共8页Journal of Time and Frequency

基　　金：国家重大科学仪器开发专项(2012YQ200183)。

摘　　要：光频移是光抽运小铯钟的主要频移之一。以国产光抽运小铯钟为例,讨论了光频移的主要来源,并提出了几种减小光频移的措施,包括:提高激光束准直度,减小镜面反射杂散光;综合利用原子饱和吸收谱和原子束荧光谱,校准探测光束和原子束的垂直度;特殊设计光回收结构和工艺,有效抑制漫反射杂散光;设计温度补偿电流方案,提高光频校正速率;设计基于液晶相位延迟器的光功率稳定环路,实现光功率稳定度Allan方差1 s进入10^(-5)量级,远端在10^(-4)量级;在确保原子高效抽运的情况下,结合整钟频率准确度变化趋势,选择合理的探测光功率。将前述减小光频移的措施实际应用于12台光抽运小铯钟产品,实测结果显示:将拟合误差值纳入评估,光频移系数bmax区间在2.04×10^(-13)/mW到4.96×10^(-13)/mW之间,按典型光功率值1.3 mW估算,长期稳定度受光频移的实际影响远小于6.45×10^(-16),对于目前批产的小铯钟而言,这部分频移量的影响是可以忽略的。Light shift is one of the primary frequency shifts of optically pumped cesium atomic clock.This article takes the domestic optically pumped cesium atomic clock as an example to discuss the major sources of its light shifts and propose several measures to reduce the light shifts.Including reducing the mirror reflection of stray light by improving the laser beam collimation;Calibrating the verticality of the detection laser and atomic beam by comprehensively utilizing atomic saturation absorption spectrum and atomic beam fluorescence spectrum;Suppressing diffuse reflection stray light effectively after designing a special light recovery structure and process;Designing a temperature compensation current scheme to improve the optical frequency correction rate;Designing an optical power stabilization loop based on LCVR.The Allan deviation of optical power stability is in the range of 10^(-5)@1 s,and long-term stability is in the range of 10^(-4);Selecting a reasonable detection laser power of the clock after considering atomic pumping efficiency and the trend of frequency accuracy.The aforementioned measures to reduce light shifts are applied to 12 optically pumped cesium clock products.The results show that the light shifts coefficient bmax is between 2.04×10^(-13)/mW to 4.96×10^(-13)/mW,include error profit value.The long-term stability affected by the light shifts is less than 6.45×10^(-16).For the currently produced cesium clock,the effect of this frequency shift is negligible.

关 键 词：光抽运-光检测 商品化 铯原子钟 光频移 

分 类 号：TM935.115[电气工程—电力电子与电力传动]