提出一种使用熔石英棒和光纤构成的新型复合型相位共轭装置,并在实验中得以实现。这种组合将具有高的激光损伤阈值的大直径熔石英棒和具有较低的受激布里渊散射(SBS)阈值的光纤结合在一起,构成了振荡-放大形式的双池式受激布里渊散射结构,使得从光纤受激布里渊散射反射的斯托克斯光注入到熔石英介质中形成了强迫受激布里渊散射过程。在这种机制下,该复合型相位共轭镜较之单块熔石英棒、单根光纤或组合芯径光纤这三种形式的相位共轭镜,具有更低的受激布里渊散射阈值和更高的受激布里渊散射反射率, 而且可以在较高的输入功率下运行。实验中将其用于高重复频率高功率的激光二极管(LD)抽运激光主振荡放大(MOPA)系统中,在100 Hz重复频率下获得了42.05%的反射率,并且获得了很好的光束质量,光束质量因子M2值从输入光束的3减少到1.6,反射光斑稳定。在400 Hz下光束质量因子M2值达到1.7。

A new type of combined phase conjugator consisting of a fused silicon rod and an optical fiber is realized in experiment. This conjugator combines a large diameter fused silicon rod with high laser damage threshold and a fiber with a low stimulated Brillouin scattering (SBS) threshold. The composed SBS oscillator-amplifier construction of the two cells type makes a forced SBS process, in which the Stokes beam reflected from fiber injects in the fused silicon rod. According to this mechanism the combined phase conjugating mirror possesses lower SBS threshold and higher reflectivity than the conjugator with bulk fused silicon, single optical fiber or combined fiber. It can also be used in a high power laser system. In a laser diode (LD) pumped high power high repetition rate master oscillator power amplifier (MOPA) laser system with the proposed conjugator, 42.05% reflectivity under 100 Hz was obtained with high beam quality. The beam quality parameter M2 was reduced from 3 to 1.6 and the beam spot was stable. Under 400 Hz repetition the beam quality parameter M2 reached 1.7.