The optical phase-locked loop (OPLL) technology is an effective-method to realize the phase coherent of laser beam. In consideration of the loop filter influence on OPLL, a new method was presented to obtain the optimized parameters of a second order passive loop filter. Firstly, a formula was deduced to design the parameters according to the definition of phase angle margin and mathematical model of open-loop transfer function. Based on MATLAB software, a parameter optimization algorithm was formulated. Secondly, in order to calculate the parameters of Raman laser optical phase-locked loop precisely, a experiment of Doppler-free absorption spectrum was designed to get the accurate gain parameter from the piezoelectric ceramic to feedback the laser. The overshoot and regulation time of unit step response were about 6.53% and 0.584 μs, respectively, in the systematic performance simulation of closed-loop optical phase-locked system. Finally, by using Simulink tools to establish models and simulating the optical phase-locked loop system module, the lasers′ phase was locked at a high speed with 2 μs. Therefore, the method of OPLL parameters optimization has turned out reasonable. In addition, certain guidelines can be given for the circuit devise of the optical phase-locked loop in engineering applications.

We introduce a new method of simultaneously implementing frequency stabilization and frequency shift for semiconductor lasers. We name this method the frequency tunable modulation transfer spectroscopy（FTMTS）. To realize a stable output of 780 nm semiconductor laser, an FTMTS optical heterodyne frequency stabilization system is constructed. Before entering into the frequency stabilization system, the probe laser passes through an acousto-optical modulator（AOM） twice in advance to achieve tunable frequency while keeping the light path stable. According to the experimental results, the frequency changes from 120 MHz to 190 MHz after the double-pass AOM, and the intensity of laser entering into the system is greatly changed, but there is almost no change in the error signal of the FTMTS spectrum. Using this signal to lock the laser frequency, we can ensure that the frequency of the laser changes with the amount of AOM shift. Therefore,the magneto-optical trap（MOT）-molasses process can be implemented smoothly.

Cold atom interferometer based on two-photon stimulated Raman transition has been proved to be a promising way to measure g with higher precision. In this work, we first introduce the principle of atomic interference gravimetry, including the interaction between the atoms and light, the interferometry with the Raman beams and the measure of the g. Then our gravity acceleration measurement system will be introduced, including atomic fountain, Raman system and detection system. With this device, we can get the value of the g, with the uncertainty in the order of ten minus seven.

In order to choose appropriate frequency stabilization method in the atom gravimeter system under construction, Doppler-free dichroic atomic vapor laser lock (Doppler-free DAVLL) and saturated absorption spectroscopy (SAS) method were implemented on Rubidium atomic vapor. Basic principle and experimental details of both frequency stabilization methods were introduced. With restructuring of optical path and applying of self-made low noise photoelectric detector as well as digital lock module, excellent error signal was obtained. For each method, two sets of locking system were built and kept locked during 3000 s′ data acquisition . A frequency fluctuation of 629 kHz when the laser is free running and of 16.2 kHz & 31.4 kHz after locked by SAS and Doppler-free DAVLL were calculated respectively, corresponding to a frequency stability of 1.64 ×10-9 in the condition of free running and 4.21 ×10-11 &8.18 ×10-11 after locked for averaging time of 10 s. The strength and weakness of both methods were elaborated with the demand of system miniaturization. After compared with SAS, Doppler-free DAVLL isconsidered to be a promising choice for miniaturization and modularization in atom interferometry gravimeter.