高功率激光驱动器预放若干关键技术研究
文献类型：学位论文
| 作者 | 彭宇杰 |
| 学位类别 | 博士 |
| 答辩日期 | 2014 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 李学春 |
| 关键词 | 惯性约束聚变 高功率激光驱动器 固体激光技术 预放大系统 多程放大 增益窄化效应 |
| 其他题名 | Several Key Technology Research of the Pre-amplifier for High Power Laser Drivers |
| 中文摘要 | 高功率激光驱动器的结构可以分为两个部分：激光产生和激光放大。而实现激光驱动器前端对小能量种子光源的放大，是预放模块的主要功能。它将激光驱动器装置的前端种子光源与主放大分系统联系起来，对微弱的种子光源脉冲进行能量放大，并实现能量稳定输出。 传统预放系统采用多级单程MOPA构型，占用空间大、成本高昂、能量利用效益低下，日益无法满足大规模激光驱动器的需求。多程放大技术由于其特有的特点，能够在高功率激光驱动预放系统的设计中发挥其巨大的优势。本文采用多程放大技术，实现了焦耳级预放系统的研制。 本文在前人研究工作的基础上，对多程放大器的物理模型、关键单元技术、系统结构和集成技术、放大器输出性能等方面开展了系统的分析和研究。具体如下： 1、 从固体放大基本理论出发，基于F-N方程建立了多程放大器的理论模型，系统的分析了放大器各参数对输出能量、提取效率的影响。在此基础上，总结和归纳了激光放大器的基本设计理念和原则。为下一步激光系统的优化设计提供理论基础。 2、 系统的分析了预放大器的相关单元器件和单元技术。对前端种子脉冲源、钕玻璃再生放大器、空间整形单元以及钕玻璃四程放大器的结构进行阐述。完成了预放系统最关键元器件—小型化钕玻璃棒状放大器的设计和研制工作，对其增益水平、热恢复性能等参数进行了测定与分析。为小型化棒放在预放系统中的应用，实现系统小型化奠定基础。 3、 结合四程放大器的结构特点，系统地分析了系统光路排布和像传递设计的要点，分别从近场像传递和远场像传递两个方面展开描述，得到了全系统像传递的结构公式，并对系统鬼像点的规避提出了合理的解决办法。实现了全系统光路准直方案，为后期系统的定型创造条件。 4、 在以上理论基础和单元技术的支撑下，搭建了基于钕玻璃再生放大器和钕玻璃四程放大器的激光系统实验平台，形成系统样机并完成了系统基本性能的工程实验。从理论上分析并解决了系统中出现的笔形光束问题。最终，基于反射式注入构型，获得了10.3焦耳的激光输出，系统增益大于10,000倍，近场填充因子71%，调制度为1.4，91%的能量可被聚焦于2倍衍射极限内，输出能量稳定性优于2%(RMS)。系统输出性能已经全面达到NIF预放模块的水平，并能够完全满足高功率激光驱动器对预放系统的要求。 5、 在高能拍瓦激光驱动器对预放系统信噪比要求和短脉冲OPA提升激光脉冲时域信噪比的技术牵引下，进行了短脉冲OPCPA泵浦源的实验研究。根据短脉冲光参量放大对泵浦源的性能要求，设计了基于固体放大技术的短脉冲泵浦源。首先从理论上验证了利用宽带光在放大过程中的增益窄化效应获得单色(相对信号光)皮秒脉冲源的可能性，并实现了基于Nd3+:YLF再生放大器和钕玻璃同轴四程放大器的皮秒OPCPA泵浦源，并形成系统实验样机。系统最终获得了6.2mJ的基频输出以及3.0mJ的倍频光，能量稳定性优于1%(RMS)，基频光和倍频光近场为近平顶分布，由于啁啾脉冲放大的增益窄化效应，输出激光的时间宽度为8.6ps。激光系统的性能全面满足短脉冲OPCPA泵浦源的要求。 |
| 英文摘要 | The structure of most high power laser drivers can be divided to two parts, laser generation and laser amplification. The pre-amplifier system between the frontend laser oscillator and the main power amplifier system is the key unit of high power laser divers. The major function of the pre-amplifier is to boost the laser pulse from sub-nanojoule to sub-joule energy level to adjust the energy requirement of main power amplifier, which must ensure stable output energy and good beam quality Traditional pre-amplifier systems are designed as single pass multi-stage amplifier chain. This design takes up too much space, characterized by poor extraction efficiencies and high cost, and can’t meet the requirements of increasingly large scale laser drivers. The multi-pass amplification technology can bring its immense advantages to the pre-amplifier design for its features. In this dissertation, a pre-amplifier system based on multi-pass amplification configuration is developed, and 10J level energy output has been obtained. Based on predecessors'' researches, this dissertation mainly focuses on the physical model of multi-pass amplifier, the key unit technologies, the system architecture design and integrated technologies, and the performance of the amplifier system. The results are summarized as follows. Firstly, a physical model of the multi-pass amplifier is developed based on the laser amplifier theory and F-N equation. The influence of the amplifier parameter on the system out energy and the extraction efficiency is systematically analyzed. The basic conceptions and principles of the laser amplifier designing are summarized and concluded. The theoretical analyses provide theoretical fundamentals for optimal design of the multi-pass amplifier system. Secondly, the key unit technologies of the pre-amplifier are systematically analyzed. The structure of the frontend sub-system, the Nd3+ doped phosphate glass regenerative amplifier, the spatial shaping module and the four pass amplifier are described. The miniaturized amplifier head, which is the most critical component of the pre-amplifier, is designed and developed. The performance parameters of the amplifier head are measured and analyzed, including the gain characteristics and the thermally induced wavefront distortion. These key unit components and technologies lay the foundation for the system integration. Thirdly, the key point of the system optical layout and image relaying is analyzed based on the structure characteristics of the for pass amplifier. The configuration designing formulas are derived from the near field and far field image relaying. A reasonable solution of the ghost reflection is proposed, and the beam alignment scheme of the off-axis four pass optic system is developed. All the calculations and analyses create the conditions for the finalizing system. Fourthly, under the support of the theory analyses and the unit technologies, a laser experimental system and the engineering prototype based on the Nd3+ doped phosphate glass regenerative amplifier and four pass amplifier are developed, and the related experiments have been conducted. The laser system can provide 10.3J, 3ns laser pulses at 1053 nm wavelength. The output laser beam is a flat top profile with a 71% near field fill factor and modulation of 1.4, and 91% beam energy can be focused into 2 times of diffraction limits. The shot-to-shot energy stability is better than 2%(RMS). The performance of the amplifier system fully achieves the level of the NIF pre-amplifier module, and meets the requirements of the pre-amplifier of high power laser drivers. Finally, a picosecond domain OPCPA pump laser system is designed and demonstrated under the requirement of the high energy PW laser facility pre-amplifier and the temporal contrast improvement using short pulse OPCPA technology. A picosecond pump laser is demonstrated for short pulse optical parametric amplification. The possibility that the monochromatic laser can be obtained by the gain narrowing effect, is verified theoretically. And a laser system and the engineering prototype based on Nd3+: YLF regenerative amplifier and Nd3+ doped phosphate glass four pass amplifier are developed. Amplified laser pulses with 6.2mJ single pulse energy, 8.6ps pulse width, 1053nm wavelength are obtained. After frequency doubling, laser pulses with 3.0mJ energy are achieved with a 1% (RMS) fluctuation. An high gain Nd3+: YLF regenerative amplifier is used as the first stage amplifier to generate narrow-band high power laser by taking advantage of the gain narrowing effect, and a 0.3nm bandwidth is obtained in theory. The output laser beam is a top flat profile with excellent beam shaping. The performance of the laser system fully meets the requirements of the short pulse OPCPA pump laser. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15894]  |
| 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 | 彭宇杰. 高功率激光驱动器预放若干关键技术研究[D]. 中国科学院上海光学精密机械研究所. 2014. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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