In order to investigate the characters of the periodic phase-modulating beam amplifying, the model of pulse laser amplifying is improved based on the analysis of the parameters influenced by the transition lineshape of the media, such as the loss, stimulated radiation cross-section and saturated energy-density during the progress of amplifying, and the case of phase-modulated pulse laser in Nd:YLF is studied also. The pulse period of simulation based on the model is 330 ps, which is consistent with the experiment with period of 300 ps. The main factors affecting output time-waveform are studied by simulation, and the effect of phase modulation to amplitude modulation (PM-AM) conversion may be weaken if the center frequency of incident beam matches the center frequency of transition lineshape, which is useful for suppressing the effect of PM-AM conversion.

为研究周期相位调制光束的放大特性,在分析激光放大介质跃迁谱线线型对损耗、受激辐射截面及饱和能量密度等参量影响的基础上,改进了原先的脉冲放大模型。以Nd:YLF放大器为例,实验中获得的时间波形调制周期约为300 ps,与计算结果330 ps吻合较好; 同时依据该模型计算分析了影响放大输出时间波形的主要因素,入射光场中心频率与跃迁谱线中心频率的匹配能有效降低相位调制-振幅调制(PM-AM)效应,为抑制该效应提供了依据。