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题名	部分端面泵浦板条激光器研究
作者	王宁
学位类别	博士
答辩日期	2005
授予单位	中国科学院上海光学精密机械研究所
导师	陆雨田
中文摘要	传统的固体激光器都加工成长而细的棒状形式，这种棒状激光介质在承受热负荷时，径向的温度梯度使棒呈现出光学畸变，它包括热聚焦、应力感生双轴聚焦和应力感生双折射。这些热效应严重影响了输出光束的光束质量，限制了激光器的输出功率。板条激光器的的几何结构消除了应力感生双折射；光路沿"之"字形传播消除了热聚焦和应力聚焦。由于板条结构的固体激光器能够消除一级热效应，可以得到比棒状固体激光器更好的光束质量和更高的平均输出功率。传统板条激光器由于其板条晶体边角处的热效应无法避免而限制了大功率高光束质量的激光输出，而且传统板条激光器的装配也很复杂。1998年，德国夫朗和费激光技术所的杜可明等人提出了部分端面泵浦的混合腔板条激光器结构，这是一种新型的固体激光器结构，被称之为InnoSlab。部分端面泵浦的混合腔板条激光器设计，结合了传统端面泵浦固体激光器结构的泵浦体积与基模体积的有效重合，以及薄片激光器与传统板条激光器优异的散热能力，再配以混合腔，可以在充分降低热影响的同时保持高效率的运转，实现大功率高光束质量的激光输出，同时保持系统紧凑。这一技术目前具有国际先进水平，研究和成功的实现这种新型的激光器，对国内固体激光器的研究特别是发展高光束质量的高功率全固态激光器有着重要的意义。本论文研究主要做了如下几个部分的工作：（l）鉴于对这种新型激光器的原理研究报道甚少，从理论上对它进行了全面的分析研究。利用Zemax和Origin软件对波导整形系统的整形效果进行了理论模拟；利用快速傅立叶算法模拟了腔内光场分布、位相分布、近场输出光场分布、远场光强分布，并从热透镜和腔镜倾斜两个方面讨论了谐振腔的灵敏度问题，特别是针对目前离轴非稳腔的报道较少的情况，对离轴非稳腔的腔镜倾斜问题做了专门讨论；从理论上分析了热透镜效应和腔镜，倾斜对输出光束M2因子的影响；鉴于单纯用M2因子来评价非稳腔的光束质量有失公平的精况，木文提出了用M2因子和桶中功率（PIB）曲线共同来评价InnoSlab离轴非稳腔光束质量的方法，理论分析表明，腔镜倾斜对M2因子的影响和对桶中功率的影响是不完个致的；利用LASCAD软件模拟激光介质内部的热分布，获得了板条晶体内的温度分布曲线，理论分析表明，板条况I体的热分布是准一维的，可以近似认为只泊稳腔方向存在热透镜效应；板条况。体得到了良好的冷却，与实验中得到的良好的输出功率曲线相符合。（2）研究成功利用进口LD单bar合成高功率LDStack，光束质子让和并束效率比能够买到的现成产品好得多。此工作对打破高功率LDStack对华禁运有一定的意义。（3）虽然我们对德方的波导整形系统只是有一个基本的认识，其具体设计过程和装调技术细节并不了解，而且现有的玻璃材料也与德方所用的玻璃材料有所不同，但我们仍然成功的设计出了波导整形祸合系统，所使用的玻璃材料以及透镜的参数与德方不同，并自行摸索出了一整套光学装调的方法，得到了很好的整形效果和较高的整形效率。（4）在对原创者的工艺技术知之甚少的条件下，摸索出具有自己特色的热沉结构和焊接工艺，实现了晶体与热沉之间优良的平面接触和紧密联结，取得了很好的冷却效果，并且在保护板条晶体免除机械应力方面优于德国的设计方案。（5）最后，在理论研究、实验研究和工艺技术探索的基础上，首次在国内实现了部分端面泵浦板条激光器，得到了最高34W的连续激光输出，光束质量MZ＜2，效率＞40％。随着输出功率的增加，输入一输出曲线没有出现平顶或下弯的迹象，光束质量因子MZ也没有明显的变坏，可见该激光器还有很大的提升空间。进一步加大泵浦功率，有望得到更高功率的高光束质量激光输出。
英文摘要	For the conventional solid state laser, the serious thermal effect of rod crystal astricted the beam quality and the output power. The appearance of slab laser is exciting for developing and applying high power solid laser. The conventional slab laser is face-pumped and face-cooled. The one-order thermal focusing, stress birefringence and depolarization can be avoided by designing zig-zag pathway rightly. The output power and the beam quality are better than those of the solid laser using rod crystal. Unfortunately, the thermal influence at the end faces and edges still disturbs the laser beam. In addition, designing and building a zigzag slab laser is complicated. In 1998, partially end-pumped slab laser was reported by Kerning Du, Fraunhofer Institut fur Lasertechnik. This is as a novel solid laser, namely InnoSlab. It has the effective overlap between pump volume and fundamental mode as conventional end-pumped solid laser, and the excellent cooling capacity as disk laser and conventional slab laser. Combining the hybrid resonator with partially end-pumping, the output power can be scaled at high beam quality, reducing the thermal effect greatly and keeping the compact configuration simultaneously. This laser is at international advanced level. Realizing and studying this laser in China is very important to develop high power solid state laser with good beam quality in China. The work in this thesis has many sections: (1) Because the theoretic research for this novel laser is very little now, the theoretic analyzing is showed in this thesis. Utilizing Zemax and Origin software, the reshaping effect is simulated for the waveguide reshaping system; By Fast Fourier Transform algrithm, the field distribution is simulatied, inside resonator and outside, near-field distribution and far-field distribution. The output phase distribution is also calculated in this thesis. In additional, the resonator sensitivity is analyzed, concerning with thermal lens effect and mirror tilt. Especially, since the report about off-aixs unstable resonator is very littlt, the minor till about off-aixs unstable resonator is analysed; The output beam quality is discussed in this thesis. The effects about thermal lens effect and mirror tilt to M2 value is also showed. Valuing beam quality is unfair, only using M2 parameter. So we add the Power In Bucket(PlB) parameter to value beam quality with M2 value. The simulation showed the effects to M parameter and PIB are different, induced by mirror tilt; The thermal effects is calculated by LASCAD software. The simulation showed the thermal distribution is quasi-one-dimensional. It can be considered approximately that the thermal lens effect is only at unstable resonator direction. The slab crystal is cooled well. It can be indicated by experiments. (2) High power self-made LD Stack is composed by several imported LDA bars. The beam quality and combining efficiency are better than that we can buy now. This work is senseful to break the embargo of high power LD Stack to China. (3 ) Although we know something about the waveguide reshaping system made in Germany, we do not know the details of designing and assembling skills. We designed the waveguide reshaping system, the glass material and lens parameters are different with those made in Germany. Furthermore, we found a optical method to adjust the system; Good reshaping effect and high transform efficiency are obtained by this method. Although we do not know the Germanic cooling technics, we designed the cooling heat sink and found the jointing technics. By these technics, the good plane contacting and compact jointing are realized. It is better than that of Fraunhofer Institut fur Lasertechnik in protecting slab crystal. The experiments indicated good cooling effect. Finally, at the base of theoretics analyzing, experiments and technics research, partially end-pumped slab laser is firstly realized successfully in China. 34W output CW laser is obtained, with M2<2 and more than 40% efficiency. With the output power curve increasing, the input-output power curve is not flat-topping and reflexed. The M2 parameter is still good. The experiments indicated this laser can be improved more and more. The higher output power will be obtained with good beam qualiy.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/15481]
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	王宁. 部分端面泵浦板条激光器研究[D]. 中国科学院上海光学精密机械研究所. 2005.

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