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题名	高功率光纤激光阵列相干组束技术研究
作者	薛宇豪
学位类别	博士
答辩日期	2011
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，光纤激光阵列，相干组束，光反馈环形腔
其他题名	Study on beam coherent combination technology of high power fiber laser arrays
中文摘要	光纤激光器具有结构紧凑、转换效率高、光束质量好、易于散热和易于实现高功率等特点，在很多领域具有广泛应用，如工业加工、通讯、医疗、科学研究和军事等。随着应用领域的不断扩展，对光纤激光器的输出功率和光束质量提出了越来越高的要求。目前，虽然采用种子光-振荡放大（MOPA）方式的单根光纤激光器的输出功率已经达到万瓦，但由于受限于非线性效应、光纤端面损伤、热透镜效应等因素的影响，单根光纤激光器的输出功率毕竟有限。多个高功率光纤激光组束进行功率合成是获得更高功率激光输出的有效途径之一，相干组束技术可以在保持激光良好光束质量的同时使得激光输出功率得以提高，是目前国际上高功率固体激光技术领域的研究热点。本文主要对高功率光纤激光阵列的被动相干组束技术进行了理论和实验研究。 第一章综述了光纤激光器的的原理、特点、发展史和最新进展。介绍了光纤激光阵列各种非相干组束和相干组束技术的基本原理和最新进展，并对各种不同组束技术进行了比较分析。 第二章建立了基于光反馈环形腔结构的光纤放大器阵列模型，介绍了光反馈环形腔被动相干组束技术的相位锁定原理，分析了单模反馈光纤的空间滤波作用。研究了被动相干组束技术的光束路数扩展性，计算了多路光纤阵列组束后的Strehl比和中心主瓣能量分布问题，数值模拟了其在有相位差和零相位差下的远场光斑图样。 第三章开展了基于光反馈环形腔结构的光纤放大器阵列的被动相干组束实验研究，建立了多路光纤激光环形腔相位锁定实验装置，实现了2路、4路和8路光纤放大器阵列的稳定同相锁定。以4路光纤放大器阵列被动相干组束为例，实验研究了单模反馈光纤位置对相干输出特性的影响，获得了三种典型非同相模式下的相位锁定。发现了相位锁定时多纵模可同时随机输出的光谱特性，采用窄带滤光片实现了对组束后光谱宽度的有效控制。研究了8路光纤激光阵列光束排列方式对相干组束效果的影响。 第四章对单链路高功率光纤激光器与光纤放大器进行了实验研究，单根大芯径双包层掺镱光纤激光器获得了1.75 kW的多模输出，研究了百微米粗芯光纤激光器的模式控制技术，采用小孔限模技术，改善了输出激光光束质量。对基于泄漏模结构的一种新型超大模场光纤的激光特性进行了实验研究，在未采取模式控制的情况下，百微米芯径光纤获得了M2<3的高功率激光输出。建立了单链路多级光纤放大系统，以窄谱线激光和单频激光作为种子光源，分别实现了305 W和216 W的放大激光输出。 第五章建立了基于光反馈环形腔结构的四链路高功率光纤激光阵列被动相干组束实验系统，实现了1062 W的相干耦合输出。研究了准直光束口径、阵列光束占空比和单路激光功率增加对相干输出特性的影响，并对该技术的相干功率可提升性进行了详细分析。由于采用了MOPA结构和被动相干组束系统宽带运行的特点，该方法可以实现更高功率和高光束质量的相干输出。
英文摘要	Thanks to their compactness, high conversion efficiency, high beam quality, good heat dissipation and high power, fiber lasers have been widely used in many fields, such as industry, communication, medicine, science research, military affairs and so on. With the development of applications, it needs laser source with high power and high beam quality. The output power of a single fiber laser by master oscillator power-amplifier (MOPA) has been improved rapidly and has reached 10 kilowatt. However, the ultimate output power from single fiber laser is limited by the nonlinear effects such as stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS), fiber end damage, thermal effect and so on. The technology of beam combination of fiber lasers array is an effective way to obtain higher power laser with high beam quality. It has become research focus in the field of high-power solid-state laser. In this paper, passive coherent beam combination of high power fiber laser arrays is researched theoretically and experimentally. In the first chapter, the principle, characteristic, history and latest developments are introduced. The technology of beam combination of fiber laser arrays is briefly introduced, and various techniques are compared and analyzed. In the second chapter, the model of fiber amplifier arrays with ring cavity is built. The principle of phase locking by passive coherent beam combination is analyzed. The function of single mode feedback fiber is researched. And the array size scalability of passively coherently phased fiber laser arrays is explored. The Strehl ratios and energy of central lobe are calculated. The far-field intensity distribution for large array size is simulated when phase error is zero and nonzero. In the third chapter, passive coherent beam combination of fiber amplifier arrays with ring cavity is experimentally demonstrated. And the phases of 2, 4, 8-channel fiber arrays are locked stable. As an example of coherent beam combination of 4-channel fiber amplifier arrays, three typical out-of-phase locked modes are obtained by shifting the feedback fiber. We observe that it output multi-longitudinal mode simultaneously and random. By using band filter, the output spectrums are controlled effectively. The effect of near-field arrangement on coherent beam combination is research in 8-channel fiber laser arrays. In the fourth chapter, we experimentally research the single chain high power fiber laser and amplifier. The output power of single large-core double-clad Yb-doped fiber laser reach to 1.75 kW. By mode controlling to hundred-micron core diameter fiber laser, its beam quality is improved. By using leaky large-core fiber, the beam quality M2 factor is better than 3. Single chain multi-stage fiber amplifier is researched experimentally. By using narrowband and single-frequency seed source, we obtain the maximum output power with 305 W and 216 W, respectively. In the last chapter, we build the system of phase locking of four high power Yb-doped fiber amplifier arrays with ring cavity. The maximum coherent output power of the fiber array is up to 1062 W. The effect of beam diameter, duty cycle and power of single laser is researched and coherent power scaling is analyzed in detail. By using MOPA architecture in fiber amplifier and broadband operation of passively phased systems, higher power scaling with high beam quality appears feasible.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/15672]
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	薛宇豪. 高功率光纤激光阵列相干组束技术研究[D]. 中国科学院上海光学精密机械研究所. 2011.

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