Investigation Of The Experimental Parameters Of Cesium Coherent Population Trapping

Coherent population trapping (CPT) is a quantum interference phenomenon due to the interaction between atoms and the coherent light field. Because of its ultra-narrow linewidth and super-sensitivity of the magnetic field, it is gradually applied to the study of atomic clocks and magnetometers in recent years. Either atomic clocks or magnetometers, improving accuracy and reducing the volume are the goals people to pursue. This thesis focused on the way to improve the accuracy of the CPT atomic clocks and magnetometers, studied and optimized the experimental parameters, and did a little useful exploration in miniaturization of CPT atomic clocks and magnetometers. It has great significance to improve the stability of CPT atomic clock and the sensitivity of the magnetometer.First of all, we analyzed the research status of CPT atomic clocks and magnetometers, current trends, and the importance of independent research in our country. We used the basic theory of light interacting with the A-type three-level atoms to explain the basic principles of CPT, and on this basis, summed up the applications of the CPT effect. Then we analyzed the advantages and difficulties of miniaturization of CPT atomic clocks and magnetometers.Then, we introduced several preparation methods of large frequency difference and phase coherence lasers, shown our experimental method and results, and tested the phase coherence of the two coherent lasers with the method of beat-note. After that we studied experimental parameters may affect the accuracy or stability of CPT cesium atomic clocks and magnetometers, including laser intensity, the relative intensity ratio between coherent bi-chromatic light fields, beam diameter, buffer gas, magnetic field and cell temperature. Therefore, we had made a theoretical analysis and parameter optimization.We then measured and analyzed the output characteristics, linewidth and high frequency modulation characteristics of the Vertical Cavity Surface Emitting Lasers (VCSEL). It is most likely to become miniaturized light source of future CPT.Finally, the main results of the thesis are summarized and an outlook is given about the prospects of the CPT future development.