铯原子汽室中光学厚度的实验测量与精确模拟

Experimental Measurements and Accurate Simulation of the Optical Thickness of the Cesium Atom Vapor

对铯原子汽室中不同能级和不同温度的原子在不同光强和不同偏振光作用下的光学厚度进行了实验测量。理论上通过建立每个塞曼子能级的速率方程,利用龙格-库塔算法求得了布居数随时间演化的数值解,从而得到了依赖于时间的吸收系数。考虑到原子热运动以及光束束宽对光学厚度的影响,利用数值积分得到了原子共振频率附近的平均吸收系数,进而利用比尔法对光通过铯原子汽室的透射曲线进行了精确的拟合,最终得到了实验系统中原子汽室光学厚度的精确值。理论分析和实验结果表明,随着温度的升高,光学厚度迅速增大;随着光强的增加,光学厚度略有变小。

The experimental measurements of the optical thickness of the cesium atom vapor interacting with the lights of different intensities and polarizations at different energy levels and temperatures are demonstrated. The rate equations of each Zeeman sublevels are established theoretically and the numerical solution of time-dependent absorption coefficients is obtained by solving the rate equations with Runge-Kutta methods. The average absorption coefficients at resonant frequency can be calculated by numerical integration because of the effects of the thermal motion of atoms and beam width. The fitting of transmission spectrum of the cesium vapor cell is carried out accurately by using the Beer＇s law and then the accurate values of the optical thickness of the cesium atom vapor are obtained finally. Theoretical analysis and experimental result show that higher temperatures lead to larger optical thickness while higher optical intensities result in smaller optical thickness.