| 题名 | 高能量宽带CPA、OPCPA放大器及其泵浦源研究 |
| 作者 | 李文启 |
| 文献子类 | 博士 |
| 导师 | 梁晓燕 |
| 关键词 | 拍瓦级超强超短激光 petawatt ultra-intense ultra-short laser pulse 光参量啁啾脉冲放大 optical parametric chirped pulse amplification 千焦耳泵浦源系统 pump source system 啁啾脉冲放大 chirped pulse amplification |
| 其他题名 | Research on the high energy and broadband amplifiers of CPA, OPCPA and the pump sources |
| 英文摘要 | 自2003年国际上首次实现拍瓦级飞秒激光输出以来，超强超短激光进入拍瓦（PW：1015 W）时代并迅速地发展，使得人们可以在实验室条件下创造出前所未有的极端物理环境，从而为强场激光物理的研究创造了先进的实验条件。拍瓦级飞秒激光系统兼具超高峰值功率和超短脉冲宽度，其聚焦峰值功率密度可达1022 W/cm2，使激光与物质的相互作用步入了相对论光学的范畴。因此，拍瓦级飞秒激光不仅促进了一些前沿学科（诸如等离子体物理，激光尾波场电子加速，质子成像和阿秒光学等）不断取得重大突破，还成为了军事和医学等领域的重要研究工具。目前，世界各国主要的激光实验室正以十拍瓦甚至更高峰值功率为目标争相展开研究工作，以期推进各领域的发展和对未知的探索。 本文依托中科院上海光机所强光实验室研制的拍瓦级激光装置以及中科院上海光机所与上海科技大学联合实验室研制的上海超强超短激光装置（SULF），主要围绕数百焦耳量级的高能量宽带啁啾脉冲放大（CPA）和光参量啁啾脉冲放大（OPCPA）的放大性能开展了研究，研制了适用于OPCPA和CPA的千焦耳高能量泵浦源并研究分析了其各项关键单元技术，在基于大口径LBO晶体放大器的OPCPA-1.0 PW和大口径钛宝石放大器的CPA-10 PW实验上均取得了重大进展。本论文的工作内容主要包括： 1. 建立了求解三维耦合波方程组的时空数值计算模型，从时间和空间上分析了OPCPA的放大性能及其低转换效率的根本成因。基于对OPCPA放大性能的分析，提出了两种在维持增益带宽的同时，提高OPCPA转换效率的优化方法，包括基于共形包络理论的信号光光谱整形和基于两种几何构型的多程非共线OPCPA结构。依据优化方案，设计了一台可以支持十拍瓦输出的百焦耳量级基于非线性晶体的OPCPA终端放大器。关于两种优化方法的论文分别发表在由SCI收录的Optics Communication和Optics Express杂志上。 2. 以实现十拍瓦激光峰值功率的输出为目标，兼顾OPCPA和CPA技术对泵浦源的需求，研制了适用于OPCPA和CPA的千焦耳高能量泵浦源，并针对系统整体集成和各项关键单元技术开展了研究，包括千焦耳泵浦源的总体设计结构、泵浦源的前端及自动准直设计、泵浦光的传输与准直、千焦耳泵浦源的激光放大器以及大口径KDP倍频器等。 3. 搭建了一套基于钕玻璃棒状和片状放大链的适用于OPCPA的泵浦源系统，最高输出能量为170 J@527 nm，从而实现了基于100×100 mm2口径LBO晶体的终端放大器在0.82 J种子光注入和169.1 J泵浦条件下输出45.3 J的单脉冲能量，相应的转换效率为26.3%。在72%的压缩效率条件下，获得了32 fs的压缩脉冲，激光峰值功率超过1 PW。实验验证了基于以CPA为前端以OPCPA为终端的混合式放大方案用于获得拍瓦级飞秒激光脉冲的可行性。 4. 搭建了三套基于钕玻璃放大器的适用于CPA的泵浦源系统，分别是：基于钕玻璃棒状放大链最高可输出2×50 J@527 nm的泵浦源、基于钕玻璃棒状放大链最高可输出4×70 J@527 nm的泵浦源以及基于钕玻璃棒状和片状放大链最高可输出650 J@527 nm的泵浦源，满足了10 PW激光装置中高能量CPA放大器对泵浦源的需求。 5. 时域双脉冲泵浦方案抑制寄生振荡和横向放大自发辐射。基于φ235 mm钛宝石晶体的CPA终端放大器，在140 J种子光注入和620 J泵浦条件下输出339 J的单脉冲能量，相应的转换效率为32%。在64%的压缩效率条件下，测得了21.0 fs的压缩脉宽，对应于10.3 PW的激光峰值功率输出。实验证实了时域双脉冲泵浦方案可以降低钛宝石放大器对泵浦-信号相对延时的敏感度；也证实了结合时域双脉冲泵浦方案和对低掺杂浓度钛宝石采用更接近钛宝石折射率的匹配液进行包边的方法对于抑制大口径钛宝石晶体在放大过程中的寄生振荡和横向放大自发辐射的有效性。; Since 2003, in which the first petawatt femtosecond laser was realized internationally, ultra-short ultra-intense laser stepped into the age of petawatt (PW: 1015 W) and developed rapidly. This enables people to create the unprecedented extreme physical environment at laboratory-scale, so that an advanced experiment condition can be created for the research of high field laser physics. Petawatt femtosecond laser system has both ultrashort temporal pulse-width and ultra-intense peak power, and its focused peak power density can achieve up to 1022 W/cm2, so that the relativistic optics became dominant in the interaction between laser and material. Petawatt femtosecond laser not only promotes some cutting-edge disciplines (such as plasma physics, acceleration of electron by laser tail wave field, proton imaging, attosecond optics, and etc.) to make a breakthrough unceasingly, but also becomes the important research tool in military and medical fields. At present, the major laser laboratories around the world are aiming to expand their research work with the goal of ten petawatt or even higher peak power, with a view to advancing the development of various fields and exploring the unknown things. In this dissertation, the research was focused on the amplification performance of high energy and broadband CPA and OPCPA, which was on the basis of the two facilities - the petawatt laser facility developed by the state key laboratory of high field laser physics of Shanghai Institute of Optics and fine Mechanics (SIOM) and Shanghai Superintense Ultrafast Laser Facility (SULF) established by the associated laboratory between SIOM and Shanghai-tech University. The pump sources with thousands Jouls that are suitable for OPCPA and CPA were developed, of which the key unit techniques were also researched and analyzed. The significant progresses were obtained on the two experiments, that is the OPCPA-1.0 PW based on the large-aperture LBO crystal amplifier and the CPA-10 PW based on the large-aperture Ti:Sapphire amplifier. The main works of the paper includes: 1. The spatialtemporal numerical simulation model was established for solving the three dimensional coupled wave equations, and the amplification performance of OPCPA as well as the reason of its low conversion-efficiency were analyzed. On the basis of the analysis, the two optimized methods were poposed for maintaining the gain bandwidth while improving the pump-to-signal conversion efficiency, including the signal spectrum shaping based on the conformal profile theory and the multi-pass noncollinear structure based on the two geometrical configurations. According to the optimized scheme, an OPCPA final amplifier with several hundreds Jouls based on the nonlinear crystal was designed for supporting the output of ten petawatt. Papers that researched on the two optimized methods were published respectively in the journals of Optics Communication and Optics Express included by SCI. 2. Aiming at realizing the output of ten petawatt laser peak power and considering the requirements of OPCPA and CPA techniques on the pump, the pump sources systems with thousands Joules that are suitable for CPA and OPCPA were developed and the overall integration of system as well as the key unit techniques were researched, including the general design structure of pump sources with thousands Joules, the front-end of pump sources as well as the design of auto-alignment, the transmission and alignment of pump beams, the laser amplifiers of pump sources with thousands Jouls, and the second harmonic generation of KDP in large aperture. 3. On the basis of the rod and disk Nd: glass amplifiers, a pump source system was built for OPCPA, and the maximum output energy was 170 J@527 nm. Based on the 100×100 mm2 LBO crystal final amplifier, the single-pulse energy output of 45.3 J with the corresponding conversion efficiency of 36.3% can be came true for injecting the signal energy of 0.82 J and the pump energy of 169.1 J. Under the condition of compress efficiency of 72%, the compressed pulse of 32 fs was measured and the super-1PW of laser peak power can be realized. The experiment proved the feasibility of the hybrid scheme with the CPA front-end and the OPCPA final-end for obtaining the petawatt laser pulses. 4. Based on the Nd: glass amplifiers，three pump sources systems were built for CPA, including a pump source based on the rod Nd: glass amplifiers with the maximum output energy of 2×50 J@527 nm, a pump source based on the rod Nd: glass amplifiers with the maximum output energy of 4×70 J@527 nm, and a pump source based on the rod and disk Nd: glass amplifiers with the maximum output energy of 650 J@527 nm, satisfying the requirements of high energy amplifiers of CPA in the 10 PW laser facility. 5. Suppressing the parasitic lasing and the transverse amplified spontaneous emission by employing the temporal dual-pulse pump scheme. Based on the Φ235 mm Ti: Sapphire crystal final amplifier of CPA, the single-pulse energy output of 339 J with the corresponding pump-to-signal conversion efficiency of 32% can be came true for injecting the signal energy with 140 J and the pump energy with 620 J. For the compress efficiency of 64%, the compress pulse of 21.0 fs was measured, corresponding to the output of 10.3 PW laser peak power. The experiment demonstrated that the sensitiviy of the Ti: Sapphire amplifier with respect to the pump-to-signal relative delay time can be decreased by using the scheme of temporal dual-pulses pump. It also proved the validity of suppressing the parasitic lasing and the transverse amplified spontaneous emission by employing both the index more-matching liquid edge-cladding technique on the Ti: Sapphire with lightly doped density and the temporal dual-pulse pump scheme. |
| 学科主题 | 光学工程 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/31059]  |
| 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 | 李文启. 高能量宽带CPA、OPCPA放大器及其泵浦源研究[D]. |
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