超短脉冲系统高信噪比种子源研究
文献类型：学位论文
| 作者 | 陈翔宇 |
| 文献子类 | 硕士 |
| 导师 | 徐光 |
| 关键词 | 超短脉冲 ultra-short pulse 光参量放大 optical parametric amplification 准相位匹配 quasi phase matching 信噪比 signal-to-noise ratio |
| 其他题名 | Study on high signal-to-noise ratio seed laser of ultra-short laser system |
| 英文摘要 | 随着超短超强激光系统应用的不断深入，对其的要求也在不断地提高，在超高光强输出的同时如何保证高的脉冲信噪比就是其中之一，它已成为影响光与物质相互作用的一个具有决定性的因素。本论文通过系统分析超短脉冲参量下转换和上转换过程的基本物理规律,建立了宽带泵浦光参量放大的理论模型和数值模拟程序，设计并优化了实验参数，提出了超短超强激光系统高信噪比种子源的实验方案；开展了高信噪比种子源实验研究工作，利用1040nm和1550nm超短脉冲激光参量下转换和上转换过程实现了高信噪比1053nm种子激光脉冲的输出，考核了其脉冲能量、光谱宽度、光束质量和稳定性等指标，验证了此项技术在超短超强激光系统高信噪比种子脉冲产生方面的工程应用可行性，为超短超强激光系统建立了信噪比主动控制技术手段。本论文主要工作如下： 1. 基于非线性耦合波方程，建立了研究宽带泵浦下光参量啁啾放大和宽带倍频过程的数值模拟程序。分析了时间同步、相位匹配温度和晶体长度对参量下转换实现3160nm输出光谱的影响，为实验中控制3160nm光谱提供指导。研究了参量下转换（OPCPA）和上转换（THG）过程中，保障1053nm种子激光输出所需的条件，为实验中激光器的参数选择提供依据。 2. 根据实际获得的30μJ、500fs、1040nm和0.2nJ、100fs、1550nm激光器参数，通过数值模拟程序，分析了光强和晶体长度对3160nm OPCPA放大及THG输出1053nm的影响，确定了对晶体长度和激光光强的要求。研究了走离效应对转换效率的影响，确定了色散控制参数。根据分析结果，设计了可行的实验方案，完成了实验光路设计。 3. 针对设计的实验方案开展了实验研究工作。利用1040nm、15ps和1550nm、10ps的展宽脉冲，通过缩束系统控制功率密度后,采用15mm PPLN晶体，实现了300 nJ（2.5% RMS）、35nm的3160nm放大输出；再经过宽带THG过程,实现了约10nJ（10% RMS）、7nm的1053nm种子输出，完成了高信噪比种子源的关键技术研究工作。 4. 基于准相位匹配的宽带OPCPA和THG技术，完成了1053nm高信噪比种子源的实验制备工作，其脉冲能量、光谱宽度、光束质量均匀和稳定性等均达到了设计要求，说明了高信噪比种子源技术的工程可行性。; With the development of ultra-short laser systems, the demands for the systems is also increasing. It is important to keep high signal-to-noise ratio with high intensity output. The signal-to-noise ratio has become a decisive factor when we study the fundamental laws of the interaction of light and matter. Based on systemic analysis of the basic physical laws of the nonlinear process of parametric down conversion and parametric up conversion of ultrashort pulse, we have established a theoretical model and a numerical simulation program for optical parametric amplification with broadband pump laser. We have designed and optimized the experimental parameters, and the experimental scheme for obtaining a high signal-to-noise ratio seed laser of ultrashort laser system is also lifted. The experiment based on the nonlinear process of parametric down conversion and parametric up conversion of 1040nm and 1550nm ultra-short pulse is carried out. A high signal-to-noise ratio output pulse at centered 1053nm is obtained, the pulse energy, spectral width, beam quality and energy stability is evaluated. The feasibility of this technique in improving the signal-to-noise ratio of the laser seed of ultrashort laser system is validated, offering a new method of controlling the signal-to-noise ratio of ultrashort laser system. The main work of this thesis includes the followings: 1. Based on coupled-wave equations, the numerical simulation program of broadband optical parametric chirped pulse amplification and broadband second harmonic generation is developed. The influence of time synchronization, phase-matching temperature and crystal length on the output spectrum of 3160nm is analyzed, providing guidance for the spectral control. The conditions required to ensure the seed laser output in the process of parametric down conversion and parametric up conversion is obtained, which provides the basis for selecting the parameters of the laser in the experiment. 2. Based on available parameters of pump laser (1040nm, 500fs, 30uJ) and signal laser (1550nm, 100fs, 0.2nJ), the effect of crystal length and pump laser intensity on the 3160nm OPCPA and 1053nm THG is studied, and the requirements of the crystal length and pump laser intensity are confirmed. The influence of walk-off time on the conversion efficiency is investigated, and the dispersion parameters is confirmed. According to the analysis results, a feasible experimental scheme is designed and the design of the optical path is completed. 3. The experiment based on the experimental scheme is carried out. Utilizing the stretched pulse (1040nm, 15ps and 1550nm, 10ps), the power intensity is controlled with the beam reducers and an output pulse centered at 3160nm is obtained, the pulse energy is 300nJ, the spectral width is 35 nm, and the energy stability is 2.5% (RMS). Via the process of third harmonic generation, a high signal-to-noise ratio output pulse centered at 1053nm is finally obtained, the pulse energy is 10nJ, the spectral width is 7 nm, and the energy stability is 10% ( RMS). The feasibility of previous design is experimentally confirmed. 4. Based on the quasi-phase-matching of broadband OPCPA and third harmonic generation, the experiment of high signal-to-noise ratio seed laser centered 1053nm is conducted, the pulse energy, spectral width, beam quality and energy stability meet the requirements. The feasibility of this technique in improving the signal-to-noise ratio of the laser seed of ultrashort laser system is validated. |
| 学科主题 | 光学工程 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/31002]  |
| 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 | 陈翔宇. 超短脉冲系统高信噪比种子源研究[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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