Research Of The Key Technique Of CPT Atomic Clock' Stability

The atomic frequency standard is the product of the combination of the atomic physics and modern electronics. It shows great influence on the development of modern Science and Technology. As increasingly stringent requirements of more portable electronic devices, quicker data rate and better ability of communications security and anti-interference, the stability and flexibility of atomic clock face more and more challenges.As based on Coherent Population Trapping CPT theory, CPT atomic clock is a new concept of atomic clocks. Without the traditional atomic clock atomic state selection system, two coherent beams of the laser frequency difference controlled by microwave signal, and applied laser field interacting with atoms three-level system, the microwave frequency is locked in the ground state hyperfine levels of atomic transitional frequencies then we can get high-precision standard frequency signal output.A higher stability of CPT atomic clock is demanded in the practical application. This paper has studied the key technologies of the CPT atomic clock stability around the layout trapping and coherent theory of CPT atomic clock and mainly contains the following three aspects:Firstly, introduce the phenomenon of coherent population trapping, and describe the mathematical model of the CPT phenomenon with quantum mechanics and a numerical simulation of the related formulas. We also analyze the various influencing factors of the CPT signal in the CPT experiment, and describe the quantum mechanics of the CPT atomic clock.Secondly, we have introduced the fabrication technique of ordinary vapor cell, some fabrication processes of the small vapor cell and the method of laser-induced heating of hollow-core glass fibers. In addition, we also designe and fabricate some vapor cells with different buffer-gas in different size on the basis of analyzing the impact of buffer gas on CPT signal .Then, we make a test and obtain prime pressure and proportion of buffer gas.Finally, this paper briefly introduces external cavity semiconductor laser and demonstrates the frequency stabilization theory, including the related concepts on frequency stabilization and reproductivity, the factors of frequency stabilization and major frequency stabilization measurements. Then, we design some photo-electricity detector, construct frequency stabilization system and detect the saturation spectrum of Rubidium. With the saturation spectrum method, the output frequency can be locked on the saturation peaks of the Rubidium.