将调Q的Nd:YAG激光脉冲聚焦到FC-72介质池中,利用电荷耦合器件(CCD)和数字图像处理技术,实验研究了后向受激布里渊散射(SBS)光斑的光强分布,获得了其光强分布及光斑大小随入射能量的变化规律。结果表明,在入射光束为基模高斯光束的条件下,随着入射光能量增大,受激布里渊散射光斑的空间光强分布由近高斯型变为高斯型。并且受激布里渊散射光斑大小总体上是随着入射光能量的增大而逐渐减小的。当入射能量在受激布里渊散射阈值附近时,受激布里渊散射光斑大小达到最大(大于入射光斑);当入射能量为3倍阈值以上时,受激布里渊散射光斑大小达到最小(小于入射光斑)。

Through focusing Q-switched laser pulses into FC-72 medium, the intensity profile of backward stimulated Brillouin scattering (SBS) spot is investigated experimentally by charge-coupled device (CCD) camera and digital image processing technology, and the rules of intensity profile and spot size versus pump energy are obtained. The results show that the intensity profile of backward SBS spot turns from quasi-Gaussian to Gaussian profile when the pump energy increases. And the size of SBS spot decreases gradually in a whole with pump energy. When pump energy is near the SBS threshold, the size of SBS spot is maximum, and larger than that of pump spot. When pump energy is three times larger than the SBS threshold, the size of SBS spot is minimum and smaller than that of pump spot.