脉冲光纤激光器调Q特性的研究
文献类型：学位论文
| 作者 | 赵宏明 |
| 学位类别 | 博士 |
| 答辩日期 | 2009 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 楼祺洪 |
| 关键词 | 脉冲光纤激光器 声光调Q 大模场面积双包层光纤 中红外光纤激光器 |
| 其他题名 | Study on Q-switched character of pulsed fiber laser |
| 中文摘要 | 掺稀土元素的光纤激光器的研究和应用是目前国际激光研究领域的热点之一。同其它气体或固体激光系统相比，光纤激光器无论在效率、体积、冷却和光束质量等方面，均占有明显的优势。脉冲的光纤激光器的研究对目前和潜在应用尤为重要，如在光通信，医疗，传感，材料加工，军事等领域。脉冲光纤激光器是目前光纤激光领域比较活跃而且有很多特点的研究方向。本文的主要目的是从理论和实验两方面对掺镱的脉冲光纤振荡器进行研究。 第一章综述了国内外在双包层光纤中如何获得高峰值功率、高能量的激光脉冲的新进展，列出了三种实现脉冲激光输出的手段，包括调Q技术、锁模技术、种子振荡功率放大的Mopa系统。给出了脉冲双包层光纤激光器实现方案及关键元器件的原理、特点和关键技术。 第二章报道了一种简单的半导体激光泵浦的声光调Q的掺镱国产大模场面积双包层光纤激光器。在零级衍射输出了光束质量因子M2为2，宽度在几百纳秒左右的激光脉冲，其脉冲重复频率在1-50kHz可调。在1kHz时，激光脉冲宽度133ns，单脉冲能量0.93mJ。 第三章在实验和理论上研究了不同结构的声光调Q 的双包层光纤激光器的脉冲输出特性， 对前向、后向不同泵浦方式的掺镱调Q 双包层光纤激光器的输出平均功率、调Q 脉冲宽度及脉冲稳定性进行了对比及讨论。在10kHz脉冲重复频率下，后向泵浦获得斜效率为60%的脉冲激光输出，其脉冲宽度为52ns，单脉冲能量0.3mJ。利用数值差分模拟了线形腔的速率偏微分方程组，理论模拟结果与实验得到的结果相符。 第四章实验分析了声光开关时间及上升沿时间对调Q光纤激光器输出脉冲特性的影响。实验发现改变上升沿时间可以使得输出脉冲发生改变；声光开关时间确实能够制约脉冲输出的稳定性及重复频率。声光开关的上升沿时间不变，选用较长的光纤激光腔则产生分叉脉冲的现象，对此给出了解释，并进行了理论模拟。 第五章研究和实现了一种脉宽压缩的高重复频率的调Q光纤激光器，通过调节声光开关时间。获得了重频在50kHz-1.5MHz，脉宽在数十纳秒级的稳定脉冲序列，在50kHz下脉冲宽度为35ns。实验结果表明，在这种调Q方式中，脉冲的宽度随着重复频率的增加没有快速增加，因而在高重频工作下，依然可以保持窄脉宽输出。通过分析调Q激光脉冲的建立时间，分析了这种脉冲的形成机理。 中红外激光技术在医疗手术，大气通信，遥感探测及军事等领域有非常特殊而重要的应用。在第六章中给出了基于国产的掺铥双包层光纤的高功率连续激光器的研究结果。利用795nm的半导体激光器双端泵浦国产的掺铥的双包层光纤，输出50W的 2μm的中红外激光.斜效率45%。实验结果对高功率的3-5μm的中红外激光的泵浦源方案选择，具有一定的指导意义。 |
| 英文摘要 | The technique and applications of earth-doped fiber lasers is one of the research focuses in international laser research fields at present. Comparing with other solid or gas lasers, fiber laser has a distinguished superiority. It demonstrates a most attractive foreground in industry, medicine, scientific research, military affairs and so on because of its small volume, light weight, high efficiency, as well as compact architecture. Furthermore, the research of pulsed fiber laser is very important for the present and potential application. In this dissertation, theoretical and experimental study on actively pulsed Yb-doped fiber laser oscillator is presented. In the first chapter, the latest progresses and development trends of pulsed fiber, which achieved higher-power and higher energy laser pulses are reviewed. Three scheme of pulsed fiber laser are included, the master-oscillator power amplifier (MOPA), Q-switched and mode-locked techniques, the principle, characteristic and key techniques of pulsed double-clad fiber laser are presented. In the second chapter, a simple laser-diode pumped acoustic-optic Q-switched fiber laser is reported by using China-made large mode area ytterbium-doped fiber. Q-switched pulses with several hundred ns pulse duration (1 kHz-50 kHz) are achieved in the direction of the zero order output. When the repetition is 1 kHz, the pulse energy is 0.93mJ with pulse duration of 132ns. In the third chapter, the characteristics of acoustic-optic double-clad fiber laser are reported by using different pumping constructions. The comparisons and discussions of average power, pulse width and stability of Q-switched pulses between the forward pump and back ward pump conditions are presented. In experiment, the output of Q-switched pulses with 60% slope efficiency of average power, 52ns pulse width and 0.3mJ single pulse are obtained at the repetition rate of 10 kHz. Finally, the rate equations with different pump configurations are built up to analyze the Q-switched pulse, and the theoretical results agree with experimental results well. In the fourth charter, laser-diode pumping Q-switched ytterbium-doped fiber laser is studied in experiment by controlling the switching time of acousto-optic modulator (AOM). It is found that the rise time of AOM can regulate the Q-switched pulse shape and that the switching time of AOM can influence output pulse stability and pulse repetition rate. Moreover, adopting longer fiber, multi-peak Q-switched pulses appear, which agree with the results reported by foreign researcher. The simulated results are given for the multi-peak pulses. The fifth charter describes and discusses a pulse-compressed, high-repetition-rate Q-switched fiber laser by regulating the switching time. Several tens pulses train at the repetition rate range of 50kHz-1.5MHz are obtained, and the pulse width is 35ns at 50kHz. The experimental results show that pulse width will not increase quickly with the increase of repetition rate in such Q-switched fiber laser. Therefore, the Q-switched fiber lasers can high-repetition-rate pulses easily. Finally, the forming mechanism of Q-switched pulses is discussed by analyzing the build-up time for Q-switched pulses. The mid-infrared laser technology has especial and significant applications in medical surgery, atmosphere communication, remote detecting and military affair. The sixth charter introduces the research work of 2µm high-power double-clad fiber laser. The Tm-doped double-clad fiber laser has produced 50-W, 2µm laser with a slope efficiency of 53%, using 795nm laser diode arrays as two-end pumping sources. The results give a helpful guidance for the project of pumping source in the next high-power mid-infrared (3-5µm) laser systems. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15251]  |
| 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 | 赵宏明. 脉冲光纤激光器调Q特性的研究[D]. 中国科学院上海光学精密机械研究所. 2009. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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