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为了实现掺Tm光纤激光器的高功率连续运转,需要解决半导体激光器输出的低光束质量泵浦光到增益光纤包层的高效耦合问题,以及增益光纤的热管理问题.利用柱面透镜组成的望远镜光学系统对半导体激光器输出泵浦光束进行扩束,使其水平方向的光束发散角获得降低,利用45°反射切割镜对扩束后的光束进行切割,经整形处理后水平方向的光束参量积为84mm·mrad,实现了约70%的光纤端面耦合传输效率.设计了两段增益光纤串联的结构,增加了泵浦光接收端面数,获得了528W的可用泵浦功率.光纤的热管理方面,在泵浦光的输入端部(约250mm),采用了水冷金属热沉散热.基于该实验装置,利用总长度6.4m的掺Tm增益光纤,获得了最高280W的连续输出功率,激光中心波长2 015nm,对应于耦合泵浦功率的斜率效率达55.6%.实验结果表明:通过对半导体泵浦光束的整形处理,可以提高光束对增益光纤的耦合传输效率;双光纤串联的结构在增加可用泵浦功率的同时,降低了光纤端部的热负载,并使整个光纤长度上的热分布更加均匀.
In order to achieve high power continuous operation of the Tm-doped fiber laser, it is necessary to solve the problem of high coupling between the low beam quality pump light output by the semiconductor laser and the gain fiber cladding and the thermal management of the gain fiber. The telescope optics The output beam of the semiconductor laser is expanded by the system so that the divergence angle of the beam in the horizontal direction is reduced. The expanded beam is cut by a 45 ° reflection mirror, and the horizontal beam parameter after the shaping process is 84 mm · Mrad, achieving about 70% of the fiber surface coupling transmission efficiency.Designed a two-stage gain fiber series structure, increasing the pump light receiving end face number, obtained 528W available pump power.Fiber thermal management, in the Based on this experimental device, a total output power of 280W was obtained by using Tm gain fiber with a total length of 6.4m, and the laser center wavelength was 2 015nm , Corresponding to a slope of 55.6% of the coupling pump power.The experimental results show that by shaping the semiconductor pump beam, the beam-to-gain Fiber coupled transmission efficiency; double fiber series structure to increase the pump power available at the same time, reducing the fiber end of the thermal load, and the entire fiber length of the heat distribution more evenly.