高功率光纤激光器光纤熔接的功率对准技术研究

发布时间：2018-01-20 06:10

本文关键词： 高功率光纤激光器双包层光纤功率对准系统光-光转换效率光束质量　出处：《南京理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：为了提高高功率光纤激光器中双包层光纤的熔接质量,解决由于熔接点处纤芯错位导致的激光器系统光-光转换效率降低,光束质量变差等问题,研究了双包层光纤的光功率对准技术。基于经典波动理论与模式传播理论,分析了双包层光纤纤芯中只传播基模和存在高阶模时纤芯偏移与熔接点处耦合效率的关系,使用nufern 20/400大模场双包层光纤搭建对准系统,对系统的光源和模场匹配特性进行实验研究,并验证包层光和纤芯中的高阶模对耦合效率与径向偏移关系的影响,实验与理论结果表明,纤芯中的高阶模使耦合效率对径向偏移变化的敏感度降低。根据以上研究,优化了双包层光纤熔接的功率对准系统,提高了双包层光纤熔接的对准精度。理论研究了双包层光纤熔接时纤芯偏移对光束质量的影响。针对经典波动模型存在模式耦合过程不明显、计算复杂等问题,提出了模场耦合追踪模型。该模型是采用高斯变形形式表示模场的耦合过程计算不同纤芯偏移时的M2。实验测量了 mufem 20/400双包层光纤光束质量随熔接偏移量的变化关系,测量结果和理论模型吻合。采用模场耦合追踪模型,能够更高效的计算光束质量随光纤偏移的变化。采用双包层光纤熔接的对准系统研究熔接机设置参数与熔接点质量的关系,找到最佳熔接参数,使熔接点质量最优。基于该系统构建了千瓦级双端泵光纤激光器系统,光-光转换效率大于73%,光束质量优于1.22,实现了准单模输出。
[Abstract]:In order to improve the fusion quality of double-clad fiber in high-power fiber laser, the problems of optical conversion efficiency and beam quality of laser system caused by misalignment of fiber core at fusion point are solved. The optical power alignment technology of double-clad fiber is studied based on classical wave theory and mode propagation theory. The relationship between core offset and coupling efficiency at fusion point is analyzed when only the base mode is propagated in double-clad fiber core and the higher-order mode exists. The alignment system is built with nufern 20/400 large-mode double-cladding fiber. The matching characteristics of light source and mode field are studied experimentally, and the effect of high order mode in cladding light and fiber core on coupling efficiency and radial offset is verified. The experimental and theoretical results show that. The high order mode in the core reduces the sensitivity of coupling efficiency to radial deviation. Based on the above research, the power alignment system of double-clad fiber fusion is optimized. The alignment accuracy of double-clad fiber fusion is improved. The influence of core offset on beam quality is studied theoretically. The classical wave model has some problems such as the mode coupling process is not obvious and the calculation is complex. A mode field coupling tracing model is proposed, in which the coupling process of the mode field represented by Gao Si's deformation form is used to calculate the M2 of different core deviations. The mufem is measured experimentally. The relationship between beam quality and weld offset of 20/400 double-clad fiber. The measurement results are in agreement with the theoretical model. The mode field coupled tracking model is used. The alignment system of double-clad fiber welding is used to study the relationship between the parameters of welding machine and the quality of weld point, and find the best welding parameters. Based on this system, a kilowatt level dual-end pump fiber laser system is constructed. The optical to optical conversion efficiency is greater than 73 and the beam quality is better than 1.22. The quasi-single-mode output is realized.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN248

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