设计了一种基于准直聚焦透镜组的双包层掺杂光纤端面泵浦耦合系统,通过分析多模光纤耦合输出的泵浦光束参量经准直 聚焦透镜光学系统后的变换特性,给出了能够满足泵浦光束与双包层掺杂光纤内包层模场分布匹配条件的透镜组参数及其位置 参数设计要求,并利用结构参数与双包层掺杂光纤完全相同的未掺杂双包层光纤进行了耦合功率的实验测试,当泵浦源输出功 率为50 W时,获得了34.1 W的入纤泵浦功率,泵浦耦合效率达到近70%,为搭建双包层光纤激光器奠定了基础。

A coupling system for end-pumping double-clad fibers, formed by a collimating and a focusing lens, is presented. By analyzing the Gaussian beam output from multi-mode pigtail fiber propagation behavior, the parameters of the collimating and focusing lenses and their position relationship are designed for the mode-field matching condition between the pump beam exited from the pigtail of the LD and the guided mode in the inner clad of the double-clad fiber. With a section of undoped double-clad fiber, which has the same specifications as the doped double-clad fiber, the coupled power of 34.1 W is measured experimentally while the pump power output from LD of 50 W, and thus the coupling efficiency of the designed end-pumping coupling system is nearly to be 70%, which provides the foundation for double-clad fiber lasers.