【作者】 曹阳；

【导师】 史伟； 于振华；

【作者基本信息】 天津大学 ， 光学工程（专业学位）， 2017， 硕士

【摘要】 作为高功率光纤激光器的核心器件,端面光纤合束器对激光器性能起着决定性作用:端面抽运合束器的主要用途是将多束由半导体泵浦源输出的抽运光组束耦合入增益光纤,以实现对增益介质的泵浦。为实现光纤激光器高效率工作,提升激光器耐受功率,以及减少因合束器插损导致的热负荷,减轻光纤激光器的散热负担,提高抽运合束器的传输效率始终是相关领域的重要研究方向;端面激光合束器可将多束光纤激光组束至单根光纤中传输,为实现高亮度高光束质量的光纤激光输出,对该结构的性能优化具有实用价值。本文对两类端面合束器相关技术开展了研究,具体内容如下:一、理论分析了7×1端面抽运合束器熔融拉锥光纤束结构(TFB)对合束器传输效率的影响。模拟计算了抽运光纤中传输的数个极化模模式在不同锥体长度TFB中的传输效率,根据其传输损耗得出所研究合束器TFB结构所应满足的最小锥长;此外,分析比较了使用不同折射率石英管情况下各模式激光在TFB中的传输效率,得出为制作高传输效率合束器石英管所需满足的条件。通过总结理论分析结果,设计了实验制作中合束器结构。二、理论分析了端面激光合束器TFB结构和输出光纤熔接方式对输出光光束质量的影响。模拟计算了熔接时,两者错芯量不同情况下输出光的光束质量,据此改进熔接方案。三、实验研究了7×1端面抽运合束器的制作工艺。探索了利用光纤拉锥机与熔接机等实验仪器,通过组束抽运光纤、拉锥光纤束、于锥腰处截断光纤束并研磨TFB端面和熔接TFB与输出光纤等多步工艺,制备高传输效率端面抽运合束器的过程;并对制备的该抽运合束器传输效率、回光损耗和温度情况进行测试。更多还原

【Abstract】 As the key device of the high power fiber laser,the end combiner plays an important role in deciding the performance of the laser.The function of the pump combiner is coupling several beams of pump laser output from laser diodes into the gain fiber in order to pump the fiber laser.To improve the efficiency of fiber laser,raise the endurable power,and avoid overlarge heat load induced by the insertion loss,it is an important research topic to increase the transmission efficiency of the combiner.In addition,the laser combiner can transfer several beams of fiber laser into one fiber.It is significant to optimize this fiber device in order to achieve output with high power and high beam quality.In this thesis,we carry out research in both kinds of combiners;the main work is demonstrated as follow,Firstly,we theoretically analyze the influence of the structure of the tapered fused bundle(TFB)of the 7×1 end-pumped combiner on its transmission efficiency.The simulation studies the transmission efficiencies of several polarization modes propagating in the pump fibers through the TFB with different taper length to determine the minimum taper length of the TFB.In addition,we compare the transmission efficiencies of different modes’ light propagating through the TFB employing the capillaries with different refractive index,from which the requirement of fabricating high transmission efficiency combiner is achieved.At last,we put forward the propose structure of the combiner based on the results of theoretical research.Secondly,we theoretically analyze the mode of splicing between the TFB and output fiber of laser combiners in order to improve the beam quality of the output laser.We explore the influence of the differences in the off-center splicing on the beam quality to achieve an improved splicing plan.Thirdly,we explore the fabricating process of the 7×1 end pump combiner experimentally.The process which includes arraying the pump fibers,tapering the fiber bundle,cleaving the TFB at the taper waist,polishing the end of the TFB and splicing the TFB to the output fiber with the employment of fiber tapering and splicing devices is explored.Furthermore,the transmission efficiency,return loss and the internal operating temperature of one our homemade combiner with high performance are inspected.更多还原