掺Yb3＋分布反馈光纤激光器的制作和物理分析
文献类型：学位论文
| 作者 | 范薇 |
| 学位类别 | 博士 |
| 答辩日期 | 2004 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 林尊琪 |
| 关键词 | 相移 分布反馈光纤激光器 应力 偏振 单纵模 空间烧孔 光纤光栅 |
| 其他题名 | The fabrication and physical analysis of Yb3+-doped distributed feedback fiber lasers |
| 中文摘要 | ICF固体激光驱动器的前级系统作为一个高质量的种子光源，将为后级系统提供一个具有一定能量、带宽、高信噪比、高光束质量的整形脉冲。根据新一代ICF固体激光驱动器对前级系统的要求，前级系统主要包括主振荡器、脉冲整形器、分束器和再生放大器。本论文研究了将用于神光III系统的主振荡器-Yb3＋才目移分布反馈光纤激光器的制作和物理特性。本文第一章综述了与本论文有关的四方面文献。第一部分对目前世界上著名实验室的代表一美国利夫莫尔实验室的高功率激光装置上的主振荡器的发展及现状进行了综述。第二部分综述了掺Yb3＋石英光纤的光谱特性和掺Yb3＋石英光纤激光器的发展。第三部分阐述了相移分布反馈光纤激光器的历史、现状和进展。第四部分论述了与相移分布反馈光纤激光器密切相关的光纤光栅的种类、发展、制作，以及均匀光纤光栅和相移光纤光栅的光谱特性。第二章从理论上研究了掺Yb3+相移分布反馈激光器的一些特性。推导了相移分布反馈激光器的增益闭值公式，数值模拟了影响相移分布反馈激光器的增益阈值特性的因素；数值模拟了掺Yb3＋相移分布反馈光纤激光器的输出特性。这些结果对光纤相移分布反馈激光器的制作和研究该激光器的实验现象有重要的指导意义。第三章围绕相移分布反馈激光器的制作，分析了相移光纤光栅的形成过程，以及紫外光致光纤损耗对相移分布反馈激光器的影响，在此基础上，阐述了利用遮挡法和二次曝光法制作相移分布反馈激光器的过程和一些特征，并且得到了成功率接近100％的相移分布反馈光纤激光器的制作方法。在这一部分当中，主要有以下创新点：1、根据理论和实验分析，所制作的10cm的相移光纤光栅的透射谱的真实特征采用现有的监控手段很难监测得到，因此采用直接监控激光器输出的情况来监控相移分布反馈激光器的形成，而不是采用传统的监控相移光纤光栅的透射谱，从而大大提高了相移分布反馈激光器的制作成功率。2、发现并研究了紫外光致光纤损耗后，在实验中摸索出：采用遮挡法制作才目移分布反馈激光器时，当激光器第一次达到激光增益闭值时，这时的激光器的藕合常数就是能够得到最大功率输出的祸合常数。因此激光器的输出并不是随着藕合常数的增大而增大的。在得到这一规律后，使我们比较容易制作高功率输出的相移分布反馈激光器；3、由于采用遮挡法制作相移分布反馈光纤激光器，可很容易得到最大功率输出的相移分布反馈激光器，但是对于大功率输出，不容易得到高的单偏振度。所以和二次曝光法结合起来，对相移分布反馈激光器再进行轻微的二次曝光，就可得到高偏振度、高输出功率的相移分布反馈光纤激光器。4、分析和总结了相移区的大小对相移分布反馈激光器的增益闭值的影响。但是在理论分析的结果中可以看到，激光器的输出功率集中在相移区，因此相移区的大小应该还会影响激光器的输出功率。因此在相移分布反馈激光器的优化中，相移区的大小是一个必须要考虑的因素。第四章研究了非对称相移分布反馈光纤激光器的输出特性。创新性的提出，正是由于空间烧孔效应，而使得非对称相移分布反馈光纤激光器具有双向输出波长不一致的特性。由于迄今为止，不能找到193lnm的合适的镀膜材料，因此未见到193nm的紫外光的偏振特性对光纤光栅双折射的影响（该方面的报道局限于248nm）。在第五章中，我们采用布儒斯特角入射的方法，研究了制作光纤光栅的193nm紫外光的偏振特性对相移分布反馈光纤激光器的偏振特性以及光纤光栅的双折射特性的影响。这一部分工作的初始目的是用垂直于光纤光栅的轴向的193nm的偏振紫外光来制作高偏振度的相移分布反馈光纤激光器，但是很遗憾，这一工作并没有完成。但是采用平行与光纤光栅的轴向的193nm的偏振光制作光纤光栅，得到了双折射比用193nm的自然光制作的光纤光栅最大可减小5倍的光纤光栅。这一特性可用于制作用于传感器等领域的双偏振相移分布反馈光纤激光器，或者用来制作用于增益平坦滤波器的低偏振相关的长周期光纤光栅。第六章研究了应力对相移分布反馈光纤激光器的偏振特性的影响，并首次采用应力的方法得到了单偏振输出的相移分布反馈光纤激光器。第七章对相移分布反馈光纤激光器的拓展应用做了一个分析和展望。 |
| 英文摘要 | Acting as a seed light source with high quality, the front-end system of the ICF (inertial confining fusion) solid-state laser driver will provide a time shaping laser pulse with proper energy, proper bandwidth, high SNR (signal to noise ratio) and high quality for the rear system of amplifiers. The front-end system includes master oscillator, pulse shaping system, beam splitter and regenerative amplifier according to the demand of the ICF solid-state laser driver. In this thesis, the fabrication and physical characteristics of the Yb3+-doped phase shifted distributed feedback fiber lasers, which will be used as the master oscillator in the ShenGuang III facility, was investigated. In the first chapter, four aspect literatures relating to the thesis are summarized. In the first part, the development and the present situation of the main master oscillator of the high power laser facility used in Lawrence Livermore National Laboratory in America, which is the representative of the famous Lab in the world, was presented. In the second part, the optical spectrum characteristics of Yb3+ doped silica fiber and the development of Yb3+ doped silica fiber lasers were summarized. In the third part, the history, the present situation and the development of phase shifted distributed feedback fiber lasers were demonstrated. In the fourth part, the category, the development and the fabrication of the fiber grating, which was closely related to the phase shifted distributed feedback fiber laser, were discussed. Also, the optical spectrum characteristics of the uniform and phase shifted fiber grating were investigated. In the second chapter, the characteristics of Yb3+-doped phase shifted distributed feedback fiber laser was theoretically investigated. The formulas for calculation of the gain threshold of the phase shifted distributed feedback fiber lasers were deduced. And then, the factors which would influence the gain threshold of phase shifted distributed feedback laser were numerically investigated. Also, the output characteristics of the phase shifted distributed feedback fiber lasers was numerical simulated. These results are of very importance for the fabrication of the phase shifted distributed feedback fiber lasers and the research of the experimental phenomenon of the lasers. Focused on the fabrication of phase shifted distributed feedback fiber lasers in the third chapter, the formation of the phase shifted fiber grating and the influence of the UV induced fiber loss on the phase shifted distributed feedback fiber laser were investigated. Based on the results, the process and the characteristics during the fabrication of the lasers using the shielded method and double exposure method were analyzed, and then the high successful fabrication rate method was obtained. The following are the innovations in this part: According to the numerical and experimental analysis, it is difficult to monitor the true characteristics of the transmission spectrum of the 10cm phase shifted fiber grating. So I adopt directly monitoring the laser output characteristics instead of the transmission spectrum of the phase shifted fiber grating, which highly enhanced the successful fabrication rate of the phase shifted DFB fiber lasers. After the investigation of the UV-induced fiber loss, it was found that the optimum coupling coefficient for maximum output power of the fiber DFB laser was just near the numerical value of the coupling coefficient when the laser first reached the gain threshold. Then it can be verified that the laser output power does not increase with the enhancement of the coupling coefficient. As these laws were obtained, it became easier to fabricate phase shifted distributed feedback fiber laser with high output power. It is easy to obtain high output power using the shielded method to fabricate the phase shifted fiber DFB lasers. But single polarization rate is low when output power is high. Then combining the double exposure method, the high single polarization rate and high output power of phase shifted DFB fiber lasers can be obtained. The influence of the magnitude of the phase shift region on the phase shifted DFB fiber lasers was analyzed. According to the numerical analysis, the output power focused on the phase shift region. So the magnitude of the phase shift region also has the influence on the output power of the DFB fiber lasers. Then the magnitude of the phase shift region must be considered during the optimization of the laser. The output characteristics of the asymmetric phase shifted DFB fiber lasers were investigated in the fourth chapter. And it was put forward that just due to the spatial hole burning, the output wavelength was different for the two output ports of the asymmetric phase shifted DFB fiber lasers. Until now, it is difficult to find the optimum coating materials for 193nm, so the influence of the polarization light of 193nm on the birefringence of the fiber grating was not found yet (the correlating reports localized on the 248nm). In the fifth chapter, the influence of the polarized UV light of 193nm on the polarization characteristics of the DFB fiber lasers and the birefringence of the fiber grating was investigated, of which the polarized light of 193nm was obtained by incident with Brewster angle. The initial purpose was to fabricate high polarization rate DFB fiber laser using the polarized light perpendicular to the fiber longitudinal axis, which is a pity that the work was not accomplished. But, using the polarized light of 193nm parallel to the fiber longitudinal axis, the reduced birefringence fiber grating by five times was obtained, which can be used to fabricate dual polarization phase shifted DFB fiber lasers used in such as sensor fields or fabricate low polarization dependent long period fiber grating used as gain flattening filter. In the sixth chapter, the influence of the stress on the phase shifted distributed feedback fiber lasers was investigated. And it was the first time that the single polarization output phase shifted distributed feedback fiber lasers was obtained using the stress method. In the seventh chapter, the application of the phase shifted distributed feedback fiber lasers was looked forward. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15425]  |
| 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 | 范薇. 掺Yb3＋分布反馈光纤激光器的制作和物理分析[D]. 中国科学院上海光学精密机械研究所. 2004. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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