高功率光纤激光器大多选用掺镱双包层光纤作为增益介质, 由于光纤尺寸较小, 极易在光纤谐振腔中产生受激布里渊散射、受激拉曼散射效应。包层掺镱双包层光纤激光器中一旦发生受激拉曼散射和受激布里渊散射效应, 其产生高强度信号成为高功率光纤激光器的主要噪声来源, 影响激光输出的特性和稳定性。对包层抽运掺镱光纤激光器中的受激布里渊散射和受激拉曼散射进行了实验研究, 在单模双包层光纤中观察到受激布里渊散射和受激拉曼散射。实验结果表明, 在光纤谐振腔中, 抽运方式、谐振腔输出镜损耗、受激瑞利散射对受激布里渊散射的影响较大, 尤其是受激瑞利散射为谐振腔提供了附加反馈, 不仅压窄激光信号的线宽, 而且使得受激布里渊散射的阈值迅速降低。

The double-clad ytterbium-doped fibers are the common gain material of high power fiber lasers. Because of the small core size, it is easy to arouse the stimulated Brillouin scattering and stimulated Raman scattering effects in the fiber resonator. Once the stimulated Brillouin scattering and stimulated Raman scattering are taking place, the high intensity signals become the major noise source and play an important role on the lasers output characters. Experimental study on them is reported in this paper. The results are shown that the pump way, the output mirror reflectivity and stimulated Rayleigh scattering play important roles to them in the fiber laser resonators, especially stimulated Rayleigh scattering. Stimulated Rayleigh scattering provides additional feedback to fiber resonators, not only narrow the laser linewidth, but also make the threshold of stimulated Brillouin scattering decrease rapidly.