2能级模型处理长脉冲圆偏振光与钠原子相互作用的合理性  

Rationality in adopting 2-level model to deal with interaction between long-pulse circularly-polarized laser and sodium atoms

作　　者：柯磊[1] 李有宽[2] 

机构地区：[1]中国工程物理研究院北京研究生部,北京100088 [2]北京应用物理与计算数学研究所,北京100088

出　　处：《强激光与粒子束》2009年第8期1239-1244,共6页High Power Laser and Particle Beams

基　　金：国家高技术发展计划项目

摘　　要：采用密度矩阵方法来处理长脉冲光与钠原子的相互作用,求解24能级钠精细结构的布洛赫方程,给出参与跃迁的每个态密度随时间的演化曲线。对于圆偏振情形,发现在长脉冲(大于100 ns)的持续时间内,最终的原子通过转移只在3S1/2(2,2)到3P3/2(3,3)之间进行泵浦并且激发态达到稳态。进一步的2能级模型计算与24能级计算结果的对比表明:用2能级近似的速率方程方法取代24能级密度矩阵方法具有合理性,由此简化了模型,节约了后续研究的计算量。In this paper a full density matrix treatment is adopted to deal with the interaction between long-pulse, circularlypolarized light and the sodium atoms. The time evolution curve of each of the 24 sub-state＇s population probability can be obtained by solving the Bloch equation of twenty-four hyperfine levels. It is found that during the long pulse time（more than 100 ns）, the final transition is only between the sub-level 3S1/2 （2,2） and 3Pa/2 （3,3） and the probability of the excited sub-state has become steady. Comparison between the 2-level model and the full density matrix method proves the rationality of rate equation and the simplicity of 2-level model for the long pulse, circularly-polarized light.

关 键 词：钠信标 长脉冲 圆偏振 2能级 自适应光学 

分 类 号：O436[机械工程—光学工程]