中红外固体激光器的理论和实验研究
文献类型：学位论文
| 作者 | 唐玉龙 |
| 学位类别 | 博士 |
| 答辩日期 | 2008 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 王之江 ; 徐剑秋 |
| 关键词 | 中红外 半导体激光器 掺Tm3+光纤 自脉冲 波长调谐 被动调Q |
| 其他题名 | Theoretical and experimental research about mid-infrared solid-state lasers |
| 中文摘要 | 近年来中红外光纤激光器已经成为了国际上的研究热点。掺Tm3+光纤激光器不仅具有光纤激光器结构简洁、效率高、光束质量好、操作方便等优点，而且因为其~2μm的激光波长处于一些重要分子的吸收带，能够被应用到军事、医疗、探测、科研等重要领域。本文从实现~2μm光纤激光器的器件化、提高光纤激光器的输出功率和转换效率、压缩激光脉冲宽度等方面对掺Tm3+光纤激光器进行了研究，目的是探索中红外光纤激光器的性能和提升其输出功率，为中红外光纤激光器的实用化和产品化提供理论和实验基础。 本论文首先对半导体激光器泵浦的掺Tm3+短光纤激光器的2μm激光输出特性进行了研究，在选用高掺杂浓度和大纤芯双包层掺Tm3+光纤的条件下，从7厘米长的光纤中获得了瓦级的2μm激光功率输出。同时，还研究了一些谐振腔参数如温度、输出镜耦合率、空气间隙等对激光器性能的影响，并分析了短光纤激光器的模式状态。 本论文然后对提升掺Tm3+光纤激光器的2μm激光输出功率进行了研究，主要通过改善泵浦源的耦合方式、优化谐振腔的结构参数、提高对光纤的冷却效果等研究了高功率光纤激光器的输出特性。在采用带尾纤输出的高功率激光二极管（LD）作为泵浦源，采用双端泵浦方式对高掺杂浓度的Tm3+光纤进行泵浦，并且有效冷却光纤的情况下，获得了超过70W的2μm激光输出。另外，还对该高功率光纤激光器的光谱特性、波长红移现象等进行了分析，并且提出了获得更高输出功率的方法。 其次，本论文研究了掺Tm3+光纤激光器在输出2μm激光时的自脉冲现象，分析了Tm3+光纤激光器中自脉冲现象的成因，建立了一个模型对不同谐振腔参数情况下的自脉冲现象进行了解释，并且提出了消除Tm3+光纤激光器中自脉冲现象的方法，即采用短腔法和低输出透过率的方法。 另外，本论文对高功率掺Tm3+光纤激光器的波长调谐进行了研究。利用一个2μm波长处的变反射率透镜，通过改变谐振腔的输出透过率，我们实现了对掺Tm3+光纤激光器输出激光波长的宽范围调谐，单根光纤的调谐范围超过100 nm，输出功率水平超过20 W。同时我们还对光纤的长度调谐进行了研究，结合长度调谐和透过率调谐，波长调谐范围可以达到240 nm。 最后，本文对掺Tm3+光纤激光器的被动调Q进行了实验研究，比较了不同光纤长度对输出脉冲特性的影响。在利用Cr2+:ZnSe晶体微片被动调制5~50cm掺Tm3+光纤时，获得了120 ns的脉冲宽度和高达530 kHz的重复频率。同时，我们还对脉冲能量和峰值功率进行了分析，并提出了提高脉冲能量和峰值功率的方法。 |
| 英文摘要 | Recent years, mid-infrared fiber lasers have been an attractive research interest over the world. As one of the branches, Tm3+-doped fiber lasers have many unique advantages. First, it has the advantages of compactness, high efficiency, good beam quality and convenience due to the features of fiber lasers. Besides, its emission wavelength covers many important absorption bands of some molecules. Therefore, Tm3+-doped fiber lasers can find applications in the regions such as military, medical surgery, detecting, researching and so on. This dissertation concentrates the research of ~2μm Tm3+-doped fiber lasers, including fabrication of a high-power ~2μm fiber laser, improving output power and energy-transfer efficiency, and shortening the output pulse width. The aim is to advance the performance and output power of mid-infrared fiber lasers, so as to provide some theoretical and experimental knowledge about the fabrication and application of this kind of fiber lasers. First, we made some research about the output characteristics of a LD-pumped short Tm3+-doped silica fiber laser. Based on high doping concentration and big core double-clad fibers, we achieved Watt-level ~2μm laser output from a 7 cm-length fiber. At the same time, we analyzed the influence of cavity parameters (such as temperature, output coupling and air spacing) on the laser performance. The laser modes features were also discussed. Secondly, we explored how to improve ~2μm laser output power of Tm3+-doped silica fiber lasers, including bettering the coupling technique, optimization of the cavity and enhancing cooling efficiency of the fiber. Using two pig-tailed high-power LDs as the pump source, through both-end pumping a high Tm3+-doped double-clad fiber under efficient cooling, 70 W of laser output near 2μm was obtained. What’s more, we also analyzed the spectral features and wavelength “red-shift” of the fiber laser. The method as how to further improve output power was suggested. Thirdly, we studied the self-pulsing phenomena of Tm3+-doped fiber lasers with ~2μm laser output. Based on experimental results and theoretical analysis, we build a model to explain the self-pulsing formation under different cavity structures. At the same time, a method as how to eliminate self-pulsing in Tm3+-doped fiber lasers was proposed, that is adopting short cavities and low output couplings. Besides, wavelength-tuning high-power Tm3+-doped fiber lasers was carried out. By using a variable reflective mirror, we realized broad-band tuning of a high-power Tm3+-doped fiber laser. When one fiber was used, the tuning range was over 100 nm at ~20-W level; when fiber-length tuning was combined, the tuning range could be expanded to 240 nm. Finally, some Cr2+:ZnSe microchips were used to passive Q-switching different lengths of Tm3+-doped silica fibers. Pulse width as short as 120 ns was achieved from a 5 cm-length fiber, and pulse repetition rate as high as 530 kHz was attained with a 50 cm-length fiber. At the same time, we analyzed the pulse energy and peak power, so as to find a way to improve these two objects. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15243]  |
| 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 | 唐玉龙. 中红外固体激光器的理论和实验研究[D]. 中国科学院上海光学精密机械研究所. 2008. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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