| 题名 | 基于多谱线LD抽运的宽工作温度脉冲激光器技术研究 |
| 作者 | 谢伟 |
| 文献子类 | 硕士 |
| 导师 | 马秀华 |
| 关键词 | 宽工作温度 wide working temperature 多谱线激光二极管 multi-wavelength laser diode stack Nd:YAG六边形板条 hexagon Nd:YAG slab 全固态激光器 all-solid-state laer |
| 其他题名 | Studying on novel temperature-insensitive pulsed slab laser pumped by multi-wavelength laser diodes |
| 英文摘要 | 本论文针对结构紧凑、低电功耗及适用于野外复杂环境的宽工作温度全固态激光器在便携式设备、军用设备、空间应用平台以及无人平台等场景的应用需求，探索了基于稳定晶体对泵浦光的吸收效率，实现激光二极管泵浦的全固态激光器在宽温度范围内工作的研究。 本论文的研究工作主要分为理论研究和实验研究两部分。论文首先回顾了激光二极管泵浦的宽工作温度脉冲激光器技术的发展现状和主要的技术路线。介绍了环境温度对激光二极管泵浦的全固态激光器输出脉冲能量的影响机制，指出激光二极管发射波长随温度的漂移引起晶体对泵浦光的吸收效率下降是导致激光二极管泵浦的全固态激光器输出脉冲能量随温度变化的主要原因。研究中利用Lambert-Beer定律计算了采用不同数量中心波长的激光二极管Stack泵浦不同吸收长度的Nd:YAG 晶体时泵浦光在各温度下的吸收效率。计算结果表明，当采用三波长激光二极管Stack (λ1=804nm, λ2=807.5nm, λ3=810nm@25℃) 泵浦掺杂浓度为1.0atm%、吸收长度为46mm的Nd:YAG晶体时，Nd:YAG激光晶体对泵浦光的吸收效率在-30℃至70℃间均可保持在92%以上。根据这一结果，利用六边形板条和三波长激光二极管Stack设计了一体化的泵浦模块，并开展了宽工作温度激光器桌面验证实验。在实验中正交放置的Porro棱镜组构成了折叠谐振腔。测量结果表明，当泵浦能量为907mJ时，在10℃至45℃间实现了重复频率20Hz、脉冲能量均值为107.3mJ、相对标准偏差（RSD）为2.1%的脉冲激光稳定输出。在45℃时，测得脉冲能量在18分钟内的RSD为0.9%。运行期间激光器对应的光-光转化效率为12%左右。在10℃至45℃间输出脉冲光斑保持为5mmX5mm的方形光斑，对应的发散角约为2.8mrad。在温度为13℃、22℃和46℃时，实验测得的脉冲宽度分别为14ns、15ns和19ns。 研制了可开展环境实验试验的宽工作温度激光器原理样机，并进行了温度循环实验。实验结果显示，当泵浦电流为110A时，在-30℃至70℃间输出脉冲能量最大值106.1mJ出现在30℃处，温度偏离30℃后，脉冲能量出现了较大的波动。当温度向低温区拓展时，脉冲能量在不断下降直至稳定于65mJ之后，在-30℃上升至75mJ；当向高温区拓展时，脉冲能量一直处于下降状态，在70℃时脉冲能量仅为31.7mJ。当增加泵浦能量后，在-30℃至50℃间实现95mJ左右随温度稳定的脉冲输出能量。实验中测得激光器输出脉冲能量在-30℃和70℃处的RSD分别为0.83%和2.9%。实验中，激光器输出光束在10℃、22℃和45℃的指向的30分钟内的稳定度均在50urad左右；相对于22℃时绝对指向，在10℃和45℃时，激光束的绝对指向在竖直方向的变化的分别为：52.9urad和0.21mrad，在水平方向几乎无变化。; The background of this thesis is based on the application requirement of portable equipment, military facility, space-based and unmanned platform on compact and low power consumption all solid state laser operating within wide temperature. The study of all solid state laser working within wide temperature range based on stabilizing absorption efficiency of pump laser versus temperature is explored. In this thesis, the main contents contain theory design and experiments exploration. First, the development of laser diode pumped laser working within wide temperature range and its main technology method are reviewed. The mechanism of temperature impact on laser diode pumped all solid-state laser is introduced. It is found that laser diode exiting change of wavelength versus temperature resulting in its absorption efficiency altering has the most influence on laser output pulse energy. The absorption efficiency of pump light emitting from laser diode stack with different number of laser diode bars whose central wavelengths are different from each other are calculated according to Lambert-Beer law when they pump Nd:YAG crystal with different absorption length. It is found that stable absorption efficiency above 92% within -30℃ to 70℃ is achieved by adopting three-wavelength laser diode stack (λ1=804nm, λ2=807.5nm, λ3=810nm@25℃) to pump Nd:YAG, doped at 1.0atm%, with absorption length of 46mm. Later, based on this conclusion, by using a hexagon Nd:YAG slab and four three-wavelength laser diode stacks, a integration pump module is designed. And then, with a couple of Porro prisms forming a fold resonator, we set up a desk verify system and measure its output pulse energy. The measured results shows when pumped at 907mJ average output pulse energy of 107.3mJ with corresponding relative standard deviation (RSD) of 2.1% is obtained at the repetition frequency of 20 Hz in the temperature range of 10℃ to 45℃. The RSD of output pulse energy versus time is measured to be 0.9% at 45℃ within 18min. The corresponding optical-to-optical efficiency is about 12%. Spot size and beam divergence are 5.0mmx5.0mm and 2.8mrad. In experiment, the pulse duration of 14ns and 19ns are gained at 13℃ and 46℃ respectively. A prototype of laser working within wide temperature range is developed on which environment experiment is based. The measured results indicate a maximum pulse energy of 106.1mJ is obtained at 30℃ in temperature range of -30℃ to 70℃. When temperature deviates from -30℃, pulse energy is about to alert largely. As temperature gets higher, pulse energy is about to decline all along. The output pulse energy is measure to be 31.7mJ at 70℃. On the other hand, pulse energy can be stabilized more than 65mJ at lower temperature and pulse energy of 75mJ is obtained at -30℃. When the pumping energy is added, stable output energy around 95mJ is realized from -30℃ to -50℃. At -30℃ and 70℃, the RSD of pulse energy versus time are measured to be 0.83% and 2.9% respectively. In experiment, the laser beam point and its stability are measured. The measured result shows the stability of output beam’s absolutely point in 30min are confined around 50urad. Comparing to the output beam’s absolutely point at 22℃, the change of beam’s absolutely point in vertical direction at 10℃ and 45℃ are 52.9urad and 0.21mrad, and there is little change in the horizontal direction. |
| 学科主题 | 光学工程 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/31040]  |
| 专题 | 中国科学院上海光学精密机械研究所 |
| 作者单位 | 中国科学院上海光学精密机械研究所 |
| 推荐引用方式 GB/T 7714 | 谢伟. 基于多谱线LD抽运的宽工作温度脉冲激光器技术研究[D]. |
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