数拍瓦级超强超短激光放大中的关键科学技术问题研究
文献类型：学位论文
| 作者 | 储玉喜 |
| 学位类别 | 博士 |
| 答辩日期 | 2015 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 徐至展 |
| 关键词 | 数拍瓦 超强超短激光 啁啾脉冲放大 钛宝石 寄生振荡抑制 |
| 其他题名 | Research on the key science and technology issues in the amplification of Muliti-Petawatt-level ultra-intense and ultra-short laser |
| 中文摘要 | 1985年啁啾脉冲放大（CPA）技术的提出解决了超短激光脉冲放大的世界难题。与此同时，得益于锁模激光器的发展，尤其是钛宝石自锁模激光器的诞生使得超短激光脉冲的时间宽度进入了飞秒领域。因此，自1990s以来，基于钛宝石的CPA技术得到了迅速发展。迄今为止，世界上多个国家建立了基于钛宝石CPA技术的拍瓦（1015W，PW）级激光系统，聚焦峰值功率能够达到1021 W/cm2。如今，国际上多个著名研究机构正在竞相研制10PW量级的超强超短激光系统。 超强超短激光为众多学科领域创造出前所未有的实验室尺度的极端物理条件和实验手段。随着激光技术的发展，各个应用领域对超强超短激光的输出能量、脉宽、脉冲的聚焦特性、脉冲对比度等性能指标提出了更高的要求。所以，如何获得高能量、窄脉宽、近理想聚焦光斑、高对比度的超强超短激光是本领域的研究热点。 本论文依托中国科学院上海光学精密机械研究所研制的拍瓦量级钛宝石CPA激光系统，重点开展了数拍瓦级超强超短激光放大中的关键科学技术问题研究。主要工作在于研究钛宝石放大器的寄生振荡特性，针对不同口径的钛宝石晶体和泵浦条件，提出相应的寄生振荡抑制技术。基于不同口径的钛宝石晶体分别实现了1.26PW、2.0PW、5.0PW的超强超短激光脉冲输出。同时，为了获得更高的能量输出，创新性地提出了可支持10PW输出的钛宝石寄生振荡抑制的新技术，包括时域的双脉冲泵浦，垂直偏振泵浦等新技术。主要研究成果包括以下几个方面： 1.基于Φ80mm口径钛宝石晶体，在折射率匹配的液体包边技术基础上，从理论和实验上研究了泵浦光和信号光之间的延时对钛宝石寄生振荡抑制的影响。通过优化泵浦光与信号光之间的延时，在105J的泵浦能量下，获得了最高能量50.8J的输出。压缩效率为72%，压缩后脉冲宽度为29.0fs，对应的脉冲峰值功率达到1.26PW，是基于Φ80mm口径钛宝石晶体的最高输出峰值功率。 2.基于Φ100mm口径钛宝石晶体，在延时优化的基础上，采用更高折射率的匹配液和溶解性更好的吸收体，通过提高注入种子光的能量，终端钛宝石放大器的寄生振荡被有效抑制。在6.5J种子光注入，140J泵浦能量下，放大后的脉冲能量达到72.6 J，压缩后脉冲宽度为26.0fs，对应的脉冲峰值功率达到2.0PW，是目前国际上已报道的最高峰值功率的拍瓦级超强超短激光系统。 3.通过优化双端泵浦光的脉冲时序、泵浦光与信号光之间的延时，以及注入种子光的能量，采用低掺杂浓度的Φ150mm口径钛宝石晶体，终端钛宝石放大器的寄生振荡被有效抑制。在35J种子光注入，312J泵浦能量下，实现了最高192.3J的放大能量输出，是当前国际上基于钛宝石CPA技术输出的最高能量。该实验结果是国际上发展10PW超强超短激光系统的重要进程。 4.基于2.0PW的实验结果，通过理论模拟得到了单脉冲泵浦条件下表面横向增益随时间变化的特点，提出了采用时域双脉冲分布的泵浦光抑制钛宝石放大器寄生振荡的新技术。对比了时域单脉冲分布与双脉冲分布的泵浦光对表面横向增益的影响。通过优化泵浦光的时域分布以及种子光与泵浦光之间的延时使得表面横向增益最小化。该技术理论上可以支持10PW放大输出，并抑制钛宝石寄生振荡的发生。 5. 针对更大口径的钛宝石晶体，利用钛宝石晶体对泵浦光的偏振选择吸收特性，提出了通过改变泵浦光的偏振来降低钛宝石的吸收系数，从而抑制大口径钛宝石晶体的寄生振荡的新技术。在不同的液体包边条件下，对比了σ偏振和π偏振两种泵浦方式下的输出能量，光斑以及光谱特性。得出了在不同泵浦条件下，寄生振荡和放大的自发辐射之间的关系，为实现10PW超强超短激光脉冲输出提供了新的寄生振荡抑制技术，以及更加全面的实验研究。 |
| 英文摘要 | The Chirp-pulsed Amplification(CPA) technique proposed in 1985 has solved the international problem of ultra-short laser pulse amplification successfully. Meanwhile, thanks to the development of mode-locking laser, especially the advent of self-mode-lock Ti:sapphire(Ti:S) laser prompts the pulse duration of the ultra-short laser pulse to femtosecond(fs) domain. Therefore, the Ti:S CPA technique has been used to make the rapid development of the ultra-intense and ultra-short lasers since the 1990s. Until now, a number of countries have built the petawatt-level ultra-intense and ultra-short laser system based on the Ti:S CPA technique, and the focused intensity of the laser pulses can achieve 1021 W/cm2. At present, many famous research institutions in the world are competing for the development of 10 Petawatt (1015W, PW) laser systems. The ultra-intense and ultra-short laser can create unprecedented comprehensive laboratory scale extreme physics and experimental means. With the development of the laser technique, many application fields put forward higher requirements for ultra-intense and ultra-short lasers, including the output energy, pulse width, focusing, and pulse contrast and so on. So, how to obtain an ultra-intense and ultra-short laser with high energy, ultrashort duration and near diffraction-limitation beam quality is the hotspot in the research area. In this dissertation, we focus on the research on the key science and technology issues in the amplification of Muliti-Petawatt-level ultra-intense and ultra-short laser based on PW Ti:S laser system built in the Shanghai Institute of Optics and Fine Mechanics, CAS. The main works include the study of the property of parasitic lasing (PL) in Ti:S amplifiers, proposing the corresponding PL suppression technique against the different aperture of Ti:S crystal and pump condition. Based on the different aperture of Ti:S crystal, we have achieved ultra-intense and ultra-short laser outputs of 1.26PW, 2.0PW, and 5.0PW respectively. Meanwhile, in order to obtain a higher energy output, the innovative techniques for PL suppression are proposed to support the 10PW ultra-intense and ultra-short laser output, including the use of temporal dual-pulse pump, the σ-polarized dual-pass pumping. The main work and the main results in the thesis are summarized as follows: 1. Based on a Φ80mm Ti:S crystal and refractive index-matched liquid cladding technique, we theoretically and experimentally investigated the influence of the time delay between the seed and pump pulses on the transverse PL for a Φ80mm Ti:S amplifier. A maximum output energy of 50.8J at a pump energy of 105J was achieved by the Ti:S CPA laser system. The peak power achieved 1.26PW, with a compressor efficiency of 72% and 29.0fs pulse duration, which is the highest peak power pulse for Φ80mm Ti:S amplifiers . 2. Based on a Φ100mm Ti:S crystal, we used the refractive index liquid with higher refractive index and laser dye with readily dissolved as cladding material. Through optimizing the time delay and enhancing the injected seed energy, the PL in the final booster amplifier was suppressed effectively. Maximum output energy of 72.6 J at pump energy of 140 J was achieved, and the recompressed pulse duration was 26.0 fs. The compressor throughput efficiency was measured to be 72%, yielding a peak power of 2.0 PW, which is the highest peak power pulse yet produced in Ti:S laser systems which have been reported. 3. Through optimizing the pump-pump delay, pump-seed time delay and the injected seed energy, the PL in final amplifier composing of a lightly-doped with Φ150mm diameter Ti:S crystal was suppressed effectively. Maximum output energy of 192.3 J at pump energy of 312 J was achieved, which is the highest-energy amplified pulse produced from a Ti:S CPA system. The experimental results are a notable progress on the road to 10 PW laser. 4. Based on experimental results in the 2.0 PW Ti:S laser system, we theoretically simulated the surface transverse gain as a function of time pumped at a temporal single pulse pump. Then we propose a new technique using a temporal dual pulse pump to suppress PL in Ti:S amplifiers. We compared surface transverse gain when the pump is a temporal single-pulse pump and dual-pulse pump. We propose a new technique to support 10PW ultra-intense and ultra-short laser output, and avoid the occurrence of PL. 5. Aiming at larger-aperture Ti:S crystals, we propose a technique to reduce the absorption coefficient of Ti:S by using σ-polarized pump based on the polarized-dependent absorption characteristic of Ti:S crystals. Using the different index-matched cladding materials, we compared the output energy、amplified beam profiles and spectra of the final booster amplifier pumped at σ-and π- polarized pumping. The relationship between PL and amplified spontaneous emission (ASE) in different index-matched cladding materials was discussed. The experimental results provide a more comprehensive investigation on PL and ASE. The method can be utilized in developing 10PW ultra-intense and ultra-short laser output. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15907]  |
| 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 | 储玉喜. 数拍瓦级超强超短激光放大中的关键科学技术问题研究[D]. 中国科学院上海光学精密机械研究所. 2015. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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