光纤激光器若干关键技术研究
文献类型：学位论文
| 作者 | 夏江珍 |
| 学位类别 | 博士 |
| 答辩日期 | 2003 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 方祖捷 |
| 关键词 | Q开关 光纤光栅 掺饵光纤 光纤激光器 |
| 其他题名 | Study on some key technologies in fiber lasers |
| 中文摘要 | 光纤激光器具有许多突出的优点和特点，与光纤元件的天然兼容性；可用带宽较宽；闺值低；与半导体激光器相比，光束质量较好，噪声较低；加之紧凑、小体积、便携式、精密化等特点，因而它在光纤通信、光纤传感等领域具有重要的应用前景，受到了国际上科技界、产业界的广泛重视，成为研究的热点。本文从理论和实验上对光纤激光器的若干关键技术进行了研究，如连续光纤激光器，调Q光纤激光器，双包层光纤激光器等。论文还对作为光纤分布式温度传感系统的脉冲光源提出了一系列的要求，本文的主要内容包括以下几个方面：根据掺饵光纤激光器的速率方程，对环形腔光纤激光器的输出特性进行了理论分析，得到了光纤激光器在稳态条件下闲值功率、激光输出功率和斜率效率的解析表达式。利用数值模拟结果对光纤激光器的这些基本特性参量进行了分析和讨论，为光纤环形激光器的优化设计提供了依据。并进行了980nm的掺饵光纤激光器的实验，实验证明理论分析得到的基本特性是合理的。根据光纤激光器瞬态的速率方程，对F-P腔光纤激光器的瞬态输出特性进行了理论分析。采用数值计算方法对不同长度、不同腔面反射率、不同泵浦功率下光纤激光器输出的弛豫振荡特性进行了模拟分析。结果表明弛豫振荡频率随光纤长度增加而减小，但是随泵浦功率的变化影响很小。弛豫振荡幅度随泵浦功率上升而增加，振荡的衰减时间随激光器腔镜的反射率的增加而上升，但是不随泵浦功率变化。进行了975nm泵浦的Er／Yb共掺双包层光纤激光器的实验，实验表明理论分析得到的基本特性是合理的。讨论了M-Z干涉仪调Q光纤激光器的中心波长随干涉仪的相位变化。分析了由于M-Z干涉仪输出光强随相位差的改变而平移，致使光纤激光器的输出波长由光纤光栅带宽内M-Z干涉仪的输出光强最大波长来决定，同时对M-Z干涉仪调谐的特性也进行了分析。提出了一种新型结构的基于光纤光栅环形镜调Q技术的全光纤调Q光纤激光器，并对其调Q原理进行了分析。这种光纤光栅环行镜调Q技术的主要优点在于它同时提供了对激光输出波长的选择和对腔面反射率进行调制的功能。实验在80mW的泵浦功率下，获得了最大峰值功率为0.60W，平均功率为5.8 mw，脉宽为1.4μs。分析和讨论了一种自注入光纤激光器，这种光纤激光器是由光纤光栅外腔激光器和马赫-曾德尔干涉仪构成。马赫-曾德尔干涉仪的响应时间为毫秒量级作为Q开关装置，外腔激光器提供短脉冲作为注入的种子来减小Q开关的脉冲宽度。实验中测得的脉冲宽度为0.8μs，是马赫-曾德尔干涉仪Q开关光纤激光器脉冲宽度的五分之一。对F-P腔双包光纤激光器进行了研究。讨论了后腔镜采用不同反射率时的激光输出特性。采用反射率为95％的后腔镜，在42OmW泵浦功率下，得到了51％的斜率效率和24％的光-光转换效率。对光纤激光器中所用的光纤光栅进行了设计。将所制作的相移光纤光栅用于光纤激光器中实现了窄线宽和双波长光纤激光器。 |
| 英文摘要 | Fiber laser has a lot of merits and characteristics, such as good compatibility with fiber components and fiber systems; wide bandwidth; better beam quality and lower noise than semiconductor lasers; in addition, compact, small volume, portable, and so on. Fiber laser has good future in fiber communication and fiber sensing and other fields. Fiber laser is regarded as one of the most important components and becomes a hot point over the world. In this thesis, several key technologies of the fiber laser have been studied theoretically and experimentally, such as continuous wave fiber laser, Q-switched fiber laser, double-cladding fiber laser. Some applications of fiber lasers are discussed, especially for fiber distributed temperature sensor. The main contents of this thesis are as follows: Continuous wave erbium-doped fiber laser with ring cavity has been studied based on the rate equations. Analytical expressions on threshold pump power, laser output power and slope efficiency under stationary condition have been derived. Variations of these basic parameters with the length of erbium-doped fiber have been analyzed by the expressions and demonstrated by simulations, which will help to optimize the design of a practical erbium-doped fiber ring laser. The experimental study on erbium-doped fiber laser pumped by 980nm source was carried out, and the output characteristics were in good agreement with the theoretical calculations. Transient characteristics of F-P fiber lasers are analyzed by using the transient rate equations in this thesis. Simulation for relaxation oscillation of the laser shows that its frequency decreases with increasing of the fiber length, and changes little with pump power; the amplitude of relaxation oscillation increases with pump power; the time constant of oscillation decay ascends with increasing of reflectivity of the cavity mirror, but changes little with pump power or fiber length. The experimental results on Er/Yb co-doped double-cladding fiber laser pumped by 975mn source showed good agreement with the theoretical calculations, indicating the simulation is reasonable. Variation of the peak wavelength of Q-switched fiber laser based on Mach-Zehnder Interferometer with the optical path difference was discussed. It is shown that the peak wavelength of the Q-switched fiber laser is determined by both of FBG spectrum and of MZI spectrum. And the tunable characteristics of the laser was also analyzed. A novel Q-switched erbium doped fiber laser using a fiber Bragg grating placed in fiber loop mirror as a wavelength-selective modulator is proposed and demonstrated experimentally. Stable optical pulse with 3 dB line-width narrow than 0.07nm and pulse width of 1.0 u sec at 8 KHz repetition frequency was obtained. A self-seeded fiber laser incorporated with a fiber Bragg grating external cavity semiconductor laser and a Mach-Zehnder interferometer (MZI) was proposed. The MZI provided a Q-switching with response time in the order of micro-seconds. The FBG-ECL provided narrow pulses as seeds to shorten the Q-switched pulses. Experimentally pulse width of 0.8 us was measured, which was one fifth of the pulse width without self-seeding. The double-cladding fiber laser of F-P cavity was studied. The output characteristics of fiber laser for different reflectivity was discussed. A slope efficiency of 51% and optic-optic converted efficiency of 24% have been achieved under 420mW pump power. It is found experimentally that the peak wavelength of fiber laser incorporated with FBG is usually shifted towards longer wavelength compared to the center wavelength of FBG. The phenomenon was analyzed theoretically by taking gain spectrum of the erbium-doped fiber into account. The output characteristics were in good agreement with the theoretical calculations. FBGs used in fiber lasers were designed and fabricated. Narrow linewidth and double-wavelength fiber lasers have been obtained by using phase shifted FBGs. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15337]  |
| 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 | 夏江珍. 光纤激光器若干关键技术研究[D]. 中国科学院上海光学精密机械研究所. 2003. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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