超强超短激光脉冲信噪比提升和宽带放大技术研究
文献类型：学位论文
| 作者 | 王新亮 |
| 文献子类 | 博士 |
| 导师 | 王占山 教授 冷雨欣 研究员 |
| 关键词 | 信噪比 Signal to noise ratio 钛宝石 Ti:sapphire Ho:YLF Ho:YLF 啁啾脉冲放大 Chirped pulse amplification 增益窄化 Gain narrowing. |
| 其他题名 | Research on pulse singal-to-noise ratio enhancement and broadband amplification technology in ultraintense and ultrashort laser |
| 英文摘要 | 基于啁啾脉冲放大技术或光学参量啁啾脉冲放大技术的超强超短脉冲激光可为人类创造出相对论尺度的极端物理条件，对强场激光物理以及相关学科的前沿发展具有重要意义。激光的时域信噪比（定义为主脉冲峰值强度与时域上某个时间点的噪声强度的比值）和脉冲宽度是超强超短脉冲的两个重要参数。目前，激光信噪比提升技术已经得到广泛的研究，但由于影响脉冲信噪比的因素十分复杂，至今不断有新的弱化机制被发现、证实，同时也需要发展相应的信噪比提升技术以满足超强超短激光发展和物理实验新的需求。另一方面，激光脉冲宽度和脉冲光谱宽度紧密相关，频域中更宽的光谱带宽对应时域更窄脉宽。更高峰值功率的激光要求发展更新的、更可靠的光谱窄化抑制技术。因此超强超短激光脉冲信噪比提升和宽带放大技术研究是国内外超强超短激光发展的热点之一。此外，2 μm附近波段激光可以用于阿秒脉冲产生、气体分子监测、红外制导以及激光雷达，亦是研究热点。 本论文主要结合实验室正在研制10 PW激光系统以及新波长超短激光的需求，开展了激光信噪比提升和宽带放大技术研究，主要包括光学元件表面反射复制后脉冲导致预脉冲产生现象的研究，基于石英晶体旋光效应再生放大器增益窄化抑制激光技术研究，以及2 μm波段高重频宽带Ho:YLF放大器设计等。取得的主要研究成果如下： 1.研究了光学参量啁啾脉冲放大器中表面反射复制脉冲导致脉冲信噪比下降的机制。通过控制复制脉冲反射率以及泵浦光转化效率定量地探究了第一预脉冲强度同两者之间关系。通过实验发现在非饱和放大阶段，第一预脉冲强度正比于材料反射率和泵浦光转化效率平方的乘积。 2.发展了基于旋光效应的高增益宽带放大技术。在钛宝石再生放大器中，通过采用两块正交的钛宝石设计，结合石英晶体旋光效应，在高增益条件下（106增益）实现增益窄化抑制，输出光谱达到84 nm，相应的能量输出为2.5 mJ，实验结果与理论计算符合。压缩后脉冲宽度为18.9 fs。 3.基于Ho:YLF晶体放大模型，设计2 μm宽带双通放大器。计算表明在无整形滤波种子注入时，可以获得26.7 mJ、1 kHz脉冲放大输出。考虑到出现明显增益窄化现象，模拟计算表明采用现实可行的滤波函数，通过种子滤波的设计可以抑制增益窄化，最终输出22.5 mJ、16 nm光谱半高全宽、367 fs极限变换脉宽。; Ultraintense and ultrashort laser pulses based on chirped pulse amplification or optical parametric chirped pulse amplification have created relativistic even ultra relativistic physical condition for human beings, and it is of great significance for the study of strong field laser physics and related disciplines. The pulse signal to noise ratio (SNR) in the time domain (Defined as the ratio between the intensity of the main pulse and the noise intensity at a certain time) and pulse width of the laser are two important parameters of the ultraintense and ultrashort pulse. Until now, the degradation mechanism of the SNR and the optimization of the SNR have been widely studied. However, due to the complexity of the factors influencing the pulse SNR, new weakening mechanisms are continuously found and confirmed. At the same time, it is necessary to develop corresponding SNR enhancement technology to meet the new requirements of ultraintense and ultrashort laser development and physical experiments. Pulse width is closely related to spectral width. A wider spectral bandwidth in the frequency domain corresponds to a shorter pulse width in the time domain. Higher peak power lasers require the development of a more updated and reliable spectral narrowing suppression technology. As strong field laser physics requires higher pulse contrast and shorter pulse width, the research of pulse contrast enhancement and the study of spectral gain narrowing suppression have become a hot topic all over the world. In addition, 2 μm lasers can be used for attosecond pulse generation, gas molecule monitoring, infrared guidance and laser radar. It is also a hot issue This paper focuses on the development and operation of of a petewatt Ti: sapphire laser system. Combined with experimental requirements and the development of the 10 PW laser system, the researches of laser SNR enhancement and broadband amplification are carried out. On the one hand, we study the prepulses generation caused by the surface reflection in optical parametric chirped pulse amplification. On the other hand, the study on the gain narrowing suppression technology based on the optical rotation effect of quartz crystal in Ti:sapphire regenerative amplifier is made. Besides, the design of the 2 μm broadband and high frequency Ho:YLF amplifier is implemented. The main results obtained are listed as follows: 1.We studied the mechanism of contrast degradation in the optical parametric chirped pulse amplifier caused by the surface reflection induced post-pulses. The relationship between the intensity of the first pre-pulse and the pulse reflectivity and the conversion efficiency of the pump is quantitatively explored. It is found experimentally that the intensity of the first prepulse is proportional to the product of the reflectivity of the material and the square of the pump to signal conversion in the stage of unsaturated amplification. 2.In the Ti: sapphire regenerative amplifier, the gain narrowing is suppressed in high gain conditions (106) by using two orthogonal Ti: sapphire crystals, combined with the optical effect of quartz crystal. The output spectrum is 84 nm with 2.5 mJ energy and 10 Hz repetition frequency. The experimental results agree well with the theoretical calculation. The pulse duration is measured to be 18.9 fs after the pulse compression. 3.The amplification model of Ho:YLF is studied. By designing a two stage double pass amplifier, we can get 26.7 mJ and 1 kHz pulse amplification without using spectral filters. Considering the obvious gain narrowing phenomenon, we further design a practical spectral filter. After the suppression of the spectral gain narrowing, the output spectrum has 16 nm bandwidth, with 22.5 mJ energy and 367 fs pulse duration. |
| 学科主题 | 光学 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/31134]  |
| 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 | 王新亮. 超强超短激光脉冲信噪比提升和宽带放大技术研究[D]. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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