弯曲直径对多模光纤激光器输出性能的影响

大模场面积(LMA)多模光纤激光器的输出性能与光纤的弯曲程度有关。为研究两者之间的关系，在光纤不同弯曲直径下，对多模光纤激光器的输出性能进行了实验测量和理论计算。采用刀口法测量了不同弯曲直径下的激光光束质量因子M2，并对每种情况下光纤激光器的斜率效率进行了测量。光纤弯曲直径分别为285 mm,195 mm和130 mm时，多模光纤激光器光束质量因子M2为2.88,1.82和1.67，斜率效率为39%,35%和34%。另外，对于实验所采用的大模场面积多模光纤，理论计算了各模式损耗与光纤弯曲直径的关系。

The output capability of large mode area (LMA) multimode fiber laser depends on the fiber bending. To study the relationship, the output capability of multimode fiber laser is measured under various bending diameters, and it also be calculated theoretically. Beam quality factor M2 is measured by the means of knife edge for different bending of LMA fiber and the slope efficiency is measured separately. When bending diameters of 285 mm, 195 mm and 130 mm are used, the corresponding beam quality factors are 2.88, 1.82 and 1.67 with the slope efficiencies of 39%, 35% and 34% respectively. For the LMA multimode fiber used in the experiment, losses of different modes are calculated theoretically under various bending diameters.