| 题名 | 掺镱脉冲光纤激光的倍频特性研究 |
| 作者 | 王子薇 |
| 学位类别 | 硕士 |
| 答辩日期 | 2013 |
| 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 主振荡-放大技术 倍频 三硼酸锂晶体 β 相偏硼酸钡晶体 |
| 其他题名 | Study on second harmonic generation properties of Yb-doped pulsed fiber laser |
| 中文摘要 | 小型化、高效率的蓝绿固体激光器在激光显示、材料加工、医疗美容等领域有着十分广阔的应用前景。掺镱光纤激光器在效率、体积、成本、散热、可靠性和光束质量上，相对于传统的固体激光器都具有非常明显的优势。将光纤激光技术与非线性频率转换技术相结合，通过倍频产生高光束质量、高功率的蓝绿激光，已成为固体激光技术领域的一个研究热点。论文首先分析了高峰值功率脉冲光纤激光器的相关关键技术；然后实验研究了亚纳秒高峰值功率光纤放大器的倍频特性；最后对三能级掺镱光纤激光器及其倍频特性进行了研究。论文主要内容如下： 第一章介绍了掺镱光纤激光器的基本特性，给出并分析了光纤激光器实现脉冲激光输出的几种方案，重点介绍了基于主振荡-放大(MOPA)技术的脉冲光纤激光及其倍频技术，给出了国内外采用单通倍频、腔外谐振倍频和腔内倍频技术实现可见光激光输出的典型结构和成果。 第二章对高峰值功率脉冲光纤激光中的关键技术进行了理论分析和实验研究。首先，根据掺镱光纤放大器的速率方程和功率传输方程，研究了掺镱光纤的储能特性，考虑了抑制放大的自发辐射，分析了提高掺镱光纤可提取能量的技术途径。然后，分析了高峰值功率脉冲光纤激光器与放大器中易于产生的各种非线性效应，并提出了抑制方法；设计并搭建了一台一级光纤放大器，研究了光纤放大过程中的放大自发辐射和非线性现象对放大信号光光谱的影响。最后，介绍了高峰值功率光纤放大器的端面处理技术，在实验中抑制了放大自发辐射和非线性效应。 第三章主要研究了准四能级的亚纳秒级高峰值功率脉冲光纤放大器及其倍频特性。采用主振荡-放大(MOPA)方式对被动调Q固体种子源进行了一级光纤功率放大，以半导体激光(LD)反向泵浦掺镱双包层光纤，在重复频率为9kHz时获得了最大平均功率5.5W、峰值功率高达1MW的1064nm激光输出，其脉冲宽度小于570ps，光谱宽度约为0.15nm。输出放大激光通过起偏器后，利用温度相位匹配的LBO晶体进行单通倍频，在基频光平均功率2.7W、LBO晶体温度150.5℃时，获得了平均功率1.3W，峰值功率大于250kW的绿光激光输出，倍频转换效率48%。 第四章主要对976nm的三能级掺镱光纤激光器的倍频技术进行了研究。分析了三能级掺镱光纤激光器的基本原理与实现途径，采用棒状光子晶体掺镱光纤作为增益介质，以声光开关为调Q元件，实现了掺镱光纤的三能级运转脉冲输出，平均功率2.7W，重复频率25kHz，脉冲宽度14ns。以该976nm的光纤激光器为基频光源，采用Ⅰ类角度相位匹配的BBO晶体为倍频晶体，进行了三能级掺镱光纤激光倍频的实验研究，获得了270mW的488nm倍频蓝光激光输出，并对进一步提高倍频转换效率的技术途径进行了分析。 |
| 英文摘要 | The technology and applications of miniature, high-efficiency blue-green lasers on laser display, material processing and medical treatments have broad prospective. Comparing with traditional solid lasers, fiber lasers has outstanding superiority in efficiency, volume, expense and so on. Combing advantages of fibers laser with nonlinear frequency conversion technology can produce blue-green lasers with high quality and high power, which have become one of the research focuses in solid laser research fields at present. In this dissertation, related pivotal technology of high-peak-power fiber laser is firstly discussed; then sub-nanosecond fiber amplifier and properties of frequency doubling is experimentally studied. Finally, we study on three-level Yb-doped fiber laser and its second harmonic generation. The main contents are as follows: In the first chapter, Yb-doped fiber laser properties are introduced; then three methods of obtaining pulsed fiber laser are listed, and it is emphasis on latest progresses and development trends of fiber master-oscillator power amplifier (MOPA) system. Moreover, the latest progresses and development trends of obtaining visible lasers using single-pass frequency doubling technology, external-cavity frequency doubling technology and intracavity frequency doubling technology are also reviewed. In the second chapter, the pivotal technology of high-peak-power fiber laser is studied by both theory analysis and experimental research. Based on the virtue of laser power transmission equations and the physical model of Yb-doped fiber amplifier, energy storage property of fiber is analyzed. The methods to suppress amplified spontaneous emission (ASE), increase extracted energy are considered. Furthermore, nonlinear effects that are prone to high-peak-power fiber laser and amplifier are introduced and analyzed. A fiber amplifier is designed and built to study how ASE and nonlinear effects would affect the output spectrum. End face treatment of fibers is also introduced, which provides technical means to suppress ASE and nonlinear effects. At last, we apply endcap to our MOPA system on high peak power, and avoid ASE and nonlinear successfully. In the third chapter, sub-nanosecond Yb-doped fiber amplifier and its second harmonic generation characteristics are studied. A Q-switched laser is used to seed a one stage amplifier featuring backward pumped Yb-doped double-clad fiber as the power amplifier. Average power of maximum 5.5W with repetition rate of 9kHz is achieved，corresponding to pulse duration of 570ps，peak power of 1MW. Based on the fiber amplifier,1.3W green laser is obtained by single-pass frequency doubling using non-critical phase matching LBO crystal at 150.5℃，and its peak power reaches 250kW，conversion efficiency is 48%. In the fourth chapter, 976nm three-level Yb-doped fiber laser and second harmonic generation technique are explored. Basic principal and approaches to three-level Yb-doped fiber laser are analyzed. Rod-type photonic crystal fiber is used as gain medium, a three-level Q-switched fiber laser based on acoustic-optic Q-switched modulator is designed. Pulses of 2.7W average power, 25kHz repetition rate and 14ns pulse duration are obtained. Based on the fiber oscillator, 976nm fiber laser frequency doubling is explored. Type Ⅰ phase matching to BBO is achieved, and the maximum output power at 488nm is 270mW. At last，the method to lift conversion efficiency at 976nm is discussed. |
| 语种 | 中文 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16762]  |
| 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 | 王子薇. 掺镱脉冲光纤激光的倍频特性研究[D]. 中国科学院上海光学精密机械研究所. 2013. |
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