高效率光纤合束器关键技术研究

发布时间：2018-07-04 17:21

本文选题：光纤激光器 + 光纤合束器　；参考：《国防科学技术大学》2015年博士论文

【摘要】：光纤激光器具有转换效率高、光束质量好、热管理方便及结构紧凑等优点,在近几年得到了飞速发展,已在工业制造和国防安全等领域取得了广泛的应用,同时也是未来高功率激光发展的重要方向之一。光纤合束器是实现高功率光纤激光的核心元器件,在单台激光器中可将多个高功率泵浦源输出的功率进行合成为光纤激光器提供更高的泵浦功率。更为重要的是,光纤合束器可将多个中等功率的光纤激光器进行功率合成,以获得更高功率的光纤激光输出,彻底解决单根光纤激光器由于非线性效应、光纤端面损伤、热透镜效应等因素存在功率瓶颈的限制。攻克光纤合束器的关键技术,实现高效率高功率光纤功率合束器研制,为获得大功率光纤激光奠定强有力的技术和光纤器件支撑,已成为当今光纤激光领域亟需解决的关键问题。基于此,本论文围绕大功率光纤合束器的研制展开了全面的理论与实验研究,主要内容包括:全面回顾了各种光纤合束器的发展历史,尤其是在近年来取得的飞速发展及其在光纤激光器屡屡取得重大突破过程中发挥的关键作用,阐明了光纤合束器对于高功率光纤激光器发展的重要意义,提出了开展光纤合束器关键技术攻关研究,尤其是研究光纤激光经合束器合成后,在获得高功率光纤激光输出的同时如何实现高光束质量。详细介绍了单根光纤拉锥后的模场分布,阐述了纤芯模式到包层模式的转化过程,利用光束传输法分析了多根光纤熔融合束拉锥过程中的模场变化情况,介绍了制作高效光纤合束器所遵循的两个基本准则——绝热拉锥和亮度守恒,模拟计算了这两个准则对于合束器传输效率的影响。详细说明了光纤合束器的制作流程及关键技术,通过长期的探索尝试,实现并掌握了制作光纤合束器的关键技术,包括多根光纤紧密组束、组束后任意直径和长度的低损耗熔融拉锥、熔锥光纤束的切割及与输出光纤的低损耗熔接等,这些技术的掌握为各种不同类型光纤合束器的制作奠定了基础、提供了技术支撑。基于两个基本准则建立了泵浦合束器传输损耗理论模型,分析了拉锥比例、合束拉锥区长度、锥腰区域长度、光纤束形变对光束传输和损耗的影响。结果表明:在拉锥比例满足亮度守恒准则的情况下,合束拉锥区域越长,传输效率越高;锥腰区域越短,传输效率越高。基于掌握的制作泵浦合束器的关键技术,制作了不同型号的泵浦合束器,均获得了非常高的传输效率及高功率的合束输出:两种输入光纤为105/125μm的7×1泵浦合束器均获得了400 W以上的功率输出,传输效率均大于98%,另一种输入光纤为220/242μm的7×1泵浦合束器获得了3.81 kW的功率输出,传输效率为98.4%。建立了功率合束器模式的传输和转化模型,定量分析了熔锥光纤束占空比的大小、制作方法的选择、输出光纤纤芯直径大小以及输入臂数量对于功率合束器最终输出光束质量的影响,研究结果表明:当熔锥光纤束的占空比尽可能小、输入光纤束尽可能平行排列、输出光纤的芯径越小、输入臂数量越少时,功率合束器的光束质量越好。基于理论分析和模拟计算的结果,分别实现了输出光纤为100μm和50μm的N×1功率合束器,传输效率均大于99%,其中输出光纤为100μm的7×1功率合束器单臂可承载500 W的功率输出。制作了多种功率合束器并对效率和光束质量进行了检测,验证了所得结论的正确性。设计并制作了可适用于宽谱功率合成的3×1功率合束器,成功实现了三路超连续谱光源的合束输出,输出功率为202 W,整体效率96.6%,开辟了超连续谱获得高功率输出的新方法。
[Abstract]:Fiber laser has the advantages of high conversion efficiency, good beam quality, convenient heat management and compact structure. It has been developed rapidly in recent years. It has been widely used in the fields of industrial manufacturing and national defense security. It is also one of the important directions for the development of high power laser in the future. Fiber bundle is the realization of high power fiber excitation. The core component of light can synthesize the output power of multiple high power pump sources in a single laser to provide higher pump power for the fiber laser. Because of the nonlinear effect, the damage of the fiber end face and the thermal lens effect, the root fiber laser has the limitation of the power bottleneck. The key technology of the optical fiber bundle is to achieve the high power and high power fiber power beam splitter. It has become a powerful technology and fiber optic device support for the high-power fiber laser. It has become the fiber optic fiber. In this paper, a comprehensive theoretical and experimental research is carried out on the development of high-power fiber optic bundles. The main contents include: a comprehensive review of the development history of all kinds of fiber bundles, especially the rapid development in recent years and the great breakthroughs in fiber lasers. The key role played in the process is clarified the important significance of the optical fiber bundle for the development of high power fiber laser, and the key technologies to develop the optical fiber bundle are put forward, especially when the optical fiber laser beam is synthesized and the high beam quality is realized while the high power fiber laser output is obtained. The distribution of the mode field after the single fiber taper is presented, and the transformation process of the core mode to the cladding mode is expounded. The change of the mode field in the process of multi fiber fused tapering is analyzed by the beam transmission method. The two basic criteria, adiabatic taper and the conservation of brightness, are introduced. The influence of the two criteria on the transmission efficiency of the beam closing device. The fabrication process and key technologies of the optical fiber bundle are described in detail. Through a long period of exploration and attempt, the key technologies of the fiber bundle are realized and mastered, including the dense fiber bundles, the low loss fused tapers of any diameter and length after the group beam, the fused taper fiber bundle. Cutting and low loss fusion with output fiber, these techniques have laid the foundation for the fabrication of various types of fiber bundles and provide technical support. Based on two basic criteria, a theoretical model of the transmission loss of the pump beam splitter is established. The ratio of the taper, the length of the conical taper area, the length of the cone waist region, the beam shape of the optical fiber are analyzed. The effect of change on the transmission and loss of the beam shows that the longer the tapering ratio is, the longer the beam cone region is, the higher the transmission efficiency is, the shorter the cone waist region is, the higher the transmission efficiency. The transmission efficiency and high power beam closing output: two kinds of 7 x 1 pumped beam splitters with input fiber of 105/125 mu m all gain more than 400 W power output, the transmission efficiency is more than 98%. The other type of 7 * 1 pumping unit with input fiber is 220/242 mu m, and the power output of 3.81 kW is obtained. The transmission efficiency is 98.4%. and the power beam splitter mode is set up. The size of the duty ratio of the taper fiber bundle, the selection of the fabrication method, the effect of the output fiber core diameter and the number of the input arms on the final output beam quality of the power beam splitter are quantitatively analyzed. The results show that the duty ratio of the conical fiber bundle is as small as possible, and the input fiber bundle is as parallel as possible. The smaller the core diameter of the output fiber, the less the number of input arms, the better the beam quality of the power beam splitter. Based on the theoretical analysis and simulation results, the output fiber is 100 m and 50 m N x 1 power beam splitter respectively, the transmission efficiency is more than 99%, of which the 7 x 1 power beam of the output fiber is 100 mu m can bear 500 W single arm. The power output of a variety of power bundles is made and the efficiency and beam quality are detected. The correctness of the conclusion is verified. A 3 x 1 power beam splitter suitable for wide spectrum power synthesis is designed and produced. The output of the three road supercontinuous spectral light source is successfully realized, the output power is 202 W and the overall efficiency is 96.6%. A new method to obtain high power output from supercontinuum.
【学位授予单位】：国防科学技术大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TN248

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