高功率光纤激光功率合成技术研究
文献类型：学位论文
| 作者 | 李震 |
| 学位类别 | 博士 |
| 答辩日期 | 2012 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 周军 |
| 关键词 | 光纤激光器 相干组束 光束质量 光纤合束器 |
| 其他题名 | Study on Power Combination Technology of High Power Fiber Lasers |
| 中文摘要 | 高功率光纤激光器具有结构简单、转换效率高、散热性能好、光束质量好、易于实现高功率激光输出等优点，可广泛应用于工业加工、国防军事、医疗以及科学研究等领域。随着高功率光纤激光器应用领域的不断拓展，对其输出功率和光束质量的要求越来越高。由于光纤端面损伤以及光纤中的非线性效应等因素，单根光纤激光器的输出功率不可能无限提高。光纤激光器的功率合成技术可以将多路光纤激光的输出功率合成输出，可极大提高系统的总输出功率。在各种功率合成技术中，相干组束技术在提高总输出功率的同时能够保持较好的光束质量，是国际上激光技术领域的研究热点；光纤化功率合成器件结构简单，使用方便，是全光纤化激光器的核心元件之一。本文主要对光纤激光的环形腔被动相干组束技术、光纤激光系统光束质量的改进及评价、以及光纤泵浦合束器技术进行了理论和实验研究。 第一章综述了高功率光纤激光器的研究进展，介绍了高功率光纤激光器的发展和典型应用。综述了几种典型的光纤激光功率合成技术，介绍了光谱组束技术、主动相干组束技术、被动相干组束技术、非相干组束技术的基本原理和最新进展，介绍了常用的激光光束质量的评价参数。 第二章对光纤激光的光反馈环形腔被动锁相技术进行了研究，建立了环形腔被动锁相实验系统，实现了一维三路光纤激光的相干组束，研究了光束占空比对远场光斑图样的影响，分析了被动锁相系统的输出光谱特性。对光反馈环形腔被动锁相技术的单路功率可提升性进行了实验研究，四路二维光纤激光实现了千瓦级的相干耦合输出。对光反馈环形腔相干组束系统的抗干扰性进行了研究。通过在光纤放大链路中接入相位调制器来模拟外界环境变化等引入的相位扰动，实验研究了相位扰动频率和相位扰动幅度对远场相干光斑图样的影响，并进行了理论分析。为了提高相干组束系统反馈回路信号光功率的抗干扰性，提高系统的稳定性，设计并实现了一种可自动波长切换的双波长光纤激光器。 第三章对光纤激光系统的光束质量控制和评价进行了理论和实验研究。光纤缠绕弯曲法是改善单根光纤激光器光束质量的一种简便易行的方式，通过建立数学模型，研究了光束质量因子M2与不同光纤参数以及光纤缠绕弯曲半径的关系。采用不同参数的光纤搭建光纤激光器，并结合理论计算分析了光纤缠绕弯曲法模式控制技术的局限性。借助于环形腔被动相干组束实验平台，分别采用衍射极限倍数β和光束质量BQ对相干组束系统的光束质量进行了理论和实验研究，分析了光束占空比对β因子和BQ的影响。在不同功率水平下分别对β因子和BQ进行了测量，对相干组束系统的β因子和BQ进行了比较分析。 第四章介绍了基于光纤熔融拉锥工艺的光纤合束器制备技术，对用于泵浦光耦合的光纤化功率合成器件进行了实验研究。对光纤泵浦合束器的设计、制备工艺进行了研究，制备出7×1的光纤泵浦合束器，并对其传输效率进行了测试。利用所制备的光纤泵浦合束器，以中心波长为1018 nm的光纤光栅为谐振腔镜，进行了1018 nm全光纤化激光器的实验研究。采用空间泵浦耦合方式，获得了功率为7.5 W的1018 nm的激光输出，并对如何提高转换效率和激光输出功率进行了分析。 |
| 英文摘要 | High power fiber lasers have many advantages such as simple structure, high conversion efficiency, good heat dissipation, good beam quality and easy to achieve high power laser output, and they can be widely used in industrial processing, defense and military affairs, medical and scientific research and so on. With the development of their applications, the demands on output power and beam quality have become much greater. The output power from a single fiber laser is limited by the fiber end damage and nonlinear effects in the fiber. The power combination technology of fiber lasers can combine the output powers from multiple fiber lasers, which greatly improved the total output power of the system. In a variety of power combination technologies, the coherent beam combination technology can maintain good beam quality while improving the total output power, and it is a hot topic of international research in laser technology field; the fiber power combination component which has simple structure is easy to use, and it is one of key components in the all-fiber lasers. In this paper, ring cavity passive coherent beam combination system of fiber lasers, improvement and evaluation of beam quality of fiber laser systems and technology of fiber pump combiners are researched theoretically and experimentally. In the first chapter, the research development of high power fiber lasers are overviewed, and the developments and typical applications of fiber lasers are introduced. Several typical power combination technologies of fiber lasers are overviewed. The basic principles and latest developments of spectral beam combination technology, active coherent beam combination technology, passive coherent beam combination technology and incoherent beam combination technology are introduced separately. The common evaluation parameters of laser beam quality are introduced. In the second chapter, optical feedback ring cavity passive phase locking technology of fiber lasers is studied. Ring cavity passive phase locking experimental system is built. Coherent beam combination of an arrary of three fiber lasers in one dimension is achieved. The impact of beam duty ratio on far-field beam patterns is studied and the characteristics of output spectrum of the passive phase locking system are analyzed. Power scalability of the single chain in optical feedback ring cavity passive phase locking technology is experimentally studied. Kilowatt coherent coupled output is achieved with four fiber lasers in two dimensions. The anti-perturbation ability of the optical feedback ring cavity coherent beam combination system is studied. Through simulating the phase perturbation caused by environmental changes with a phase modulator which is inserted into the fiber amplifier chain, the impact of phase perturbation frequency and amplitude on far-field coherent beam patterns is studied experimentally and theoretical analysis is made. In order to improve the anti-perturbation ability of power of signal light in the feedback loop of the coherent beam combination system and also the system stability, a dual-wavelength fiber laser which can automatically switch the wavelength of output laser is designed and achieved. In the third chapter, the beam quality control and evaluation of fiber laser systems is studied theoretically and experimentally. The fiber coiling method is a simple way to improve the beam quality of a single fiber laser. The relationship between beam quality factor M2 corresponding to fibers with different parameters and coiling radius is studied with a numerical model. Fiber lasers are built using fibers with different parameters, and the limitation of fiber coiling method for mode controlling technique is analyzed with theoretical calculation results. With the ring cavity passive coherent beam combination experiment platform, beam quality of the coherent beam combination system is theoretically and experimentally studied using times-diffraction-limited factor β and beam quality BQ separately. The impact of beam duty ratio on β factor and BQ is analyzed theoretically. The β factor and BQ is measured separately under different power levels. A comparative analysis of the β factor and BQ of the coherent beam combination system is done. In the fourth chapter, preparation technology of fiber combiner based on fiber fused bi-conical taper process is introduced, and the all-fiber component which is used for pump laser combination is experimentally studied. The design and preparation process of the fiber pump combiner is studied. 7×1 fiber pump combiner has been made and its propagation efficiency is tested. Using fiber gratings which have a central wavelength of 1018 nm as resonator mirrors, the 1018 nm all-fiber laser is experimentally studied with the self-made fiber pump combiner. With space pump coupling method, an output power of 7.5 W 1018 nm laser is obtained and analysis on how to improve conversion efficiency and output power of the laser is done. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15692]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 李震. 高功率光纤激光功率合成技术研究[D]. 中国科学院上海光学精密机械研究所. 2012. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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