Elliptically Polarized Light Impact On Cpt Atomic Frequency Standard

CPT atomic frequency standard is a kind of high precision timing tool with the characteristics of high-accuracy, minute extension and low-power dissipation. As a result of its simple mechanical structure, the high frequency stability and accuracy, and other prominences, CPT atomic frequency standard has a high application value in the national defense, commercial and daily life.There is a λ/4wave plate be installed in the optical parts of CPT atomic frequency standard. The effect of it is to convert the linearly polarized light into circularly polarized light. In the experimental process, the laser would convert into elliptically polarized light when the angle between wave plate and the direction of light polarization drift off45°. Because of the dependent on the polarization, intensity and other parameters of laser, the performance of laser takes an important part to impact the accuracy and stability of CPT atomic frequency standard. The main purpose of this paper is to study the influence on the output signal of CPT atomic frequency standard from the laser which possesses different parameters. The principle of this paper is the atomic transition theory in quantum optics, and we adopt the semiclassical density-matrix theory to study the interaction between atomic and light. Through the numerical simulation, we draw out2-d and3-d charts which could reflect the output signals to make the further observation and analysis.In the part of theoretical tools, we introduce the interaction Hamiltonian of atomic and light, dipole approximation, elliptically polarized light, the coherent population trapping of (?)-type three-level atomic system, the density matrix equation of (?)-type three-level atomic, Rabi frequency, the operating principle and basic structure of CPT atomic frequency standard and so on. We analysis and discuss the influence of elliptically polarized light on CPT atomic frequency standards which work atoms are87Rb and133Cs when the magnetic induction of rf fields B2=0and B2≠0, respectively. The results show that the change of laser intensity, polarization angle and other parameters would arouse the change of fluorescence signal and microwave signal output from CPT atomic frequency when B2=0. If the parameters of laser are fixed, the strength of signal output from it would reduce obviously when increase B2, and if the value of B2is fixed, the strength of signal output from it would also change when we change the laser intensity, polarization angle and other parameters. The results of the numerical simulation of this paper would provide the useful reference for the further study, optimize and development of CPT atomic frequency standard.