宽频带光束非线性热像效应的实验研究

实验研究宽频带脉冲光束通过非线性介质时的非线性热像的形成过程，揭示了光束入射功率和脉冲宽度、介质厚度等因素对热像光强和位置的影响. 结果表明，与单纵模激光束一样，在宽频带脉冲光束情形下，非线性介质上游元件的模糊斑调制也可导致在下游共轭位置形成热像. 热像光强随入射光束功率的增加而增加；若脉冲能量一定，则热像光强随脉冲宽度的增加而减弱；若脉冲峰值功率一定，则热像光强随脉冲宽度的增加而增强. 关键词： 高功率激光 热像 宽带光束 小尺度自聚焦

Experimental study of the nonlinear hot image effect of broadband pulsed laser beams

The experimental investigation of the nonlinear hot image effect in brand-band pulsed laser beams is reported, placing emphasis on the observation of the formation of hot images and the influence of incident average power of pulse, pulse width, and thickness of the nonlinear medium on the location and intensity of hot images. It is shown that, hot images can be formed from obscurations in the broadband laser beam through a nonlinear Kerr medium slab, as in the case of the monochromatic continious light beam, and are located in the plane symmetrical to the obscuration with respect to the nonlinear slab. In addition, with the incident average power of pulse increasing, the intensity of hot image increases and ultimately reaches saturation, while with the pulse width increasing, the intensity of hot image decreases for a pulse of given energy. On the contrary, it increases for a pulse of given peak power.