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题名	高效高功率径向偏振光纤、固体激光器研究
作者	林迪
学位类别	硕士
答辩日期	2010
授予单位	中国科学院上海光学精密机械研究所
导师	李建郎
关键词	径向偏振激光 掺镱光纤激光器 Nd:YAG激光器 光子晶体光栅 被动调Q
其他题名	Efficient, High-power and Radially Polarized Fiber Laser and Solid-state Laser
中文摘要	径向偏振光是一种新型的矢量光束，其光束横截面上各点电场矢量方向指向半径方向，并且电场矢量和场幅均呈现轴对称性。当用高数值孔径透镜聚焦时，它具有独特的紧聚焦特性，其焦斑尺寸远小于线偏振光以及圆偏振光。该矢量光束在粒子捕获、电子加速、金属加工、高分辨率显微镜等领域均有重要的用途。在本研究中，为获得高效率、高功率以及高偏振纯度的径向偏振激光，我们分别对径向偏振Nd:YAG（微片）激光器以及径向偏振掺镱光纤激光器进行了理论以及实验研究。本轮文的布局具体如下： 第一章总体阐述了径向偏振激光的背景知识，回顾了国际上产生径向偏振激光的各种技术方案，介绍了径向偏振激光的应用前景，最后提出了本论文的研究方向以及采用的技术方案。 第二章考虑泵浦光与信号光空间模式匹配，在求解三维数率方程的基础上建立了径向偏振激光输出特性模型，为优化设计径向偏振激光器时各参数的选择提供了理论指导；实验中利用两端键合有纯YAG的Nd:YAG薄片晶体作为激光增益介质，光子晶体光栅作为径向偏振选择输出耦合镜成功获得了偏振纯度96.5%，斜效率58.1%，最大输出功率264mW的径向偏振激光。 第三章首次将光子晶体光栅应用于掺镱双包层光纤激光器中，在最大泵浦功率6.2W时获得了2.42W， 偏振纯度为95.5%的径向偏振激光。这表明在掺杂光纤中同样可以获得与固体、微片陶瓷可比拟的高偏振纯度、高效率、高功率的径向偏振激光。 第四章首次率先实现了脉冲输出的被动调Q径向偏振光纤激光器。我们以掺镱双包层光纤作为激光增益介质，以可饱和吸收晶体Cr4+:YAG作为被动调Q开关，光子晶体光栅作为具有偏振选择性的输出耦合镜，在国际上首次获得了光纤激光器的径向偏振脉冲输出。我们同时研究了Cr4+:YAG晶体不同初始透过率（T0）时径向偏振激光的输出特性。当T0=70%、泵浦功率为6W时，获得的径向偏振激光脉冲平均功率为857mW，重复频率为56.6kHz，脉宽为75ns，峰值功率为202W。
英文摘要	Radially polarized light is one member of vector beams. Both of its electric filed and amplitude are cylindrically symmetric with the direction of electric field vector points to the radial direction. When using a high-numerical- aperture lens, such vector beam can be tightly focused compared to linearly and circularly polarized beam. The radially polarized beam has found many applications, such as particle trapping, electron acceleration, metal material processing, high-resolution microscopy, etc. And now, many attentions has been paid to generate the radially polarized beam from a laser resonator with high efficiency, high power and high polarization purity. In this dissertation, we described the theoretical and experimental study on radially polarized Nd:YAG (microchip) laser and radially polarized Yb-doped fiber laser. The layout of the dissertation is as follows: In chapter 1, we overviewed the background of radially polarized vector beam, and then gave a summary on the methods to generate it as well as its related applications. We also depicted our proposals on forming the radially polarized light in Nd:YAG laser and ytterbium-doped fiber laser. In chapter 2, firstly, we presented the theoretical modeling and analysis on radially polarized solid-state laser based on spatially three-dimensional rate equations by taking the spatial match of the pumping area and lasing area into account. Furthermore, we reported the experimental study on the boned Nd:YAG microchip crystal laser by employing the photonic crystal grating as the output coupler. We obtained the radially polarized laser output with 264-mW power and 58.1% laser efficiency as well as 96.5%polarization purity. In chapter 3, we reported our first realization on an efficient, high-power and radially polarized fiber laser. In the experiment, we used ytterbium-doped multi-mode double-cladding fiber as gain fiber, the photonics crystal grating as output coupler. The laser emitted radially polarized beam, and the laser power reached 2.42W with a slope efficiency of 45.9% and a polarization purity of 95.5%. The results reveal the prospect of radially polarized fiber laser, with the inclusion of the grating mirror, is brilliant in competition with the counterpart of the solid-state microchip laser in producing radial polarized beam with high efficiency, high power and high polarization purity. In chapter 4, we presented the first realization on the radially polarized and pulsed output from a passively-Q-switched ytterbium-doped fiber laser, where a piece of Cr4+:YAG crystal was employed as the saturable absorber with the photonic crystal grating as output coupler. When Cr4+:YAG crystals with initial transmission T0= 70%, the laser emitted 56.6-kHz radially polarized pulse with 857-mW averaged power, 75-ns pulse duration and 202-W peak power at 6-W incident pump power.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/16680]
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	林迪. 高效高功率径向偏振光纤、固体激光器研究[D]. 中国科学院上海光学精密机械研究所. 2010.

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