SBS相位共轭补偿现象的实验研究与图示化分析

Experimental Research and Illustrated Analysis on SBS Phase-conjugate Compensating Phenomenon

通过实验观察了受激布里渊散射相位共轭波前补偿现象,分析了单横模激光、波前弱畸变及强畸变激光受激布里渊散射现象的差异.由于工作介质中强烈的热畸变所引起的波前破碎效应,高功率固体激光器的输出光束一般都不是理想的高斯型单横模,而是具有弱畸变或强畸变波前结构的光束,其包含多个子光束.只有总能量足够大的激光束被聚焦到布里渊介质中时,其包含的所有子光束才能各自按单横模受激布里渊散射规律产生后向散射光,再合并而实现完全的相位共轭波前反转,否则就只能实现部分相位共轭波前反转,即部分相位共轭补偿.

SBS partial phase-conjugate compensating phenomenon has been researched experimentally. The difference between single-transverse-mode laser SBS and wave-front distorted laser SBS were analyzed illustratively. High power solid state laser beams are not pure single-transverse-mode with Gaussian spatial profile, but they are wave-front distorted beams due to thermally induced phase distortions and depolarization in the gain medium. When a very intense beam is focused into Brillouin medium, all small- scale transverse-modes included in the large laser beam will produce respectively backward SBS beams,and then incorporate to realize phase conjugate wave reversion.