Realization of population inversion between 7S1/2 and 6P3/2 levels of cesium for four-level active optical clock

• Published in: Science China. Physics, mechanics & astronomy mechanics & astronomy, 2013-06, Vol.56 (6), p.1107-1110
• Main Authors: Wang, YanFei, Wang, DongYing, Zhang, TongGang, Hong, YeLong, Zhang, ShengNan, Tao, ZhiMing, Xie, XiaoPeng, Chen, JingBiao
• Format: Article
• Language: English
• Subjects: Astronomy; Cesium; Classical and Continuum Physics; Fluorescence; Laser pumping; Line spectra; Matrix methods; Observations and Techniques; Physics; Physics and Astronomy; Population inversion; 主动光学; 四能级系统; 密度矩阵方法; 时钟; 水; 泵浦激光器; 粒子数反转; 铯
• ISSN: 1674-7348; 1869-1927
• DOI: 10.1007/s11433-013-5068-7

We demonstrate experimentally the population inversion between 7S1/2 and 6P3/2 levels of cesium in thermal cesium cell with a 455.5 nm pumping laser.We calculate the relative population probabilities at each level theoretically with the density matrix method.In a steady state,5.8% atoms are at 7S1/2 level and 2.9% at 6P3/2 level,which builds up the population inversion between the two levels.We obtain the fluorescence spectra produced in thermal cesium cell in our experiment.The measured relative intensity of each available fluorescence spectral line in the experiment agrees very well with the theoretical result.The demonstrated population inversion between 7S1/2 and 6P3/2 levels can be used to construct an active optical clock of four-level system with a wavelength of 1469.9 nm.