| 题名 | 高功率超短激光脉冲精密测量技术研究 |
| 作者 | 张福领 |
| 学位类别 | 博士 |
| 答辩日期 | 2010 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 林尊琪 |
| 关键词 | 超短激光脉冲 精密测量技术 脉冲宽度 脉冲信噪比 时空畸变 |
| 其他题名 | Precise Diagnostic techniques for high power ultra-short laser pulses |
| 中文摘要 | 与高功率超短脉冲激光装置本身同样重要的是超短激光脉冲的精密测量技术。建好、用好超短脉冲激光装置的一个重要前提条件，就是要具备全面的超短脉冲诊断测量手段。本论文致力于高功率超短激光脉冲精密测量技术的研究工作，目的是为强场物理研究和惯性约束聚变领域的超短超强激光系统的安装调试和经常性的常规调整提供重要的测量依据。论文的主要工作包括以下几个方面： (1)分析了单次脉冲自相关测量的原理和定标方法，并针对数十皮秒量级的单次激光脉冲开展了脉宽测量的实验研究。研究了衍射光栅在脉冲光束中引入的横向时间延迟，并深入分析了利用衍射光栅实现非共线相关脉宽测量中两子光束间相对延时的引入的机理。通过实验演示了一个利用衍射光栅在参考光中引入横向时间延迟的灵敏的单次相关测量系统。 (2) 理论分析了脉冲能量、晶体长度和非线性晶体的材料色散(表面色散和体内色散)等因素对信噪比测量系统可测动态范围的影响。开展了高动态范围的二阶自相关信噪比测量的实验研究，在国内首次实现了~108动态范围的信噪比测量结果。通过实验研究掌握了分析判断信噪比测量过程中的误差来源和加以消除或减小的方法。 (3)开展了高动态范围的三阶互相关信噪比测量的实验研究，借助聚焦准直透镜也实现了动态范围~108的信噪比测量结果。但是，透镜本身会引入二次反射造成的干扰噪声，通过分析确认了干扰噪声的来源。在此基础提出了利用凹面镜提高可测动态范围的可行性方案。 (4)对国内外现有的单次超短激光脉冲信噪比测量方案进行了深入的分析研究。提出了新的单次脉冲信噪比测量方案(利用多组分光镜或F-P标准具进行分束)，并对其可行性进行了分析讨论。确认了单次脉冲信噪比测量方案应当采用脉冲复制器( F-P标准具的改进装置)进行分束，并针对脉冲复制器的缺陷提出了改进方案。 (5)基于平面波分别利用色散棱镜和衍射光栅推导出脉前倾斜与角色散的普适关系式。基于高斯型超短激光脉冲光束得出了含有角色散、空间啁啾和时间啁啾的超短脉冲光束的解析表达式。论证了脉前倾斜与角色散等价性理论只有在脉冲光束中不含空间啁啾时才是成立的。因为即使没有角色散，同时存在的空间啁啾与时间啁啾共同作用也会产生脉前倾斜。分析讨论了超短激光脉冲中所有可能存在的一阶时空畸变。 (6)详细分析了GRENOILLE(FROG的最新简化版本)测量系统的结构优势和测量原理，并建立了其关键元素BBO晶体的光谱滤波效应的理论模型。基于此模型计算了不同厚度的BBO晶体的倍频滤波函数的允许带宽，不但更为直观的展示了厚晶体的分光计作用，而且给出了装置中不同厚度的BBO晶体对应的可测脉冲的波长和带宽范围。给出了一个设计GRENOILLE装置的流程，并结合GRENOILLE的特点和优势，分别对利用该装置进行空间啁啾和脉前倾斜的测量方案进行了深入的理论研究和探索。 |
| 英文摘要 | The precise diagnostic techniques for high power ultra-short laser pulses are as important as the high power ultra-short laser systems themselves. Having comprehensive diagnostic techniques is a precondition to build and make full use of an ultra-short laser system. This thesis endeavors to study the precise diagnostic techniques for high power ultra-short laser pulses in order to provide references for the installation and regular adjusting of high intensity ultra-short laser systems which are used in the realm of high energy physics and inertial confinement fusion research. And the main contents of this thesis are listed below: (1)The principle and calibration method of single-shot autocorrelation measurement of the width of pulse were studied. And our experiment focused on the width measurement of tens of picosecond laser pulses. We studied the transverse time delay (TTD) introduced by gratings and deeply analyzed the mechanism of formation of the relative time delay in the noncollinear correlation measurement. We demonstrated experimentally a sensitive single-shot pulse correlation system in which a diffraction grating is used to produce a TTD in the reference pulse. (2)The factors that limit the dynamic range of noncollinear correlators were analyzed. The main physical factors are the finite energy of the pulse, the finite length of the converting crystal, and surface and bulk scattering from the crystal. We carried out a series of repetitive pulses contrast measurement according to second order autocorrelation and reached firstly a dynamic detection range of ~108 in our country. We analyzed the source of measurement error and learnt the methods to eliminate or minimize them during pulse contrast measurement. (3) We also carried out a series of repetitive pulses contrast measurement according to third order cross-correlation and reached a dynamic detection range of ~108 in virtue of lenses. But the lenses themselves can introduce background noises. We analyzed and confirmed the origins of these noises, and proposed a new scheme of using a concave mirror to enhance the dynamic range of the pulse contrast measurement system. (4)On the bases of analyzing the existent schemes of single-shot pulse contrast measurement, new schemes were proposed (using a large number of beam splitters or F-P interferometer to split beam). Considering their feasibility, we realized that pulse replicator can be used to achieve both high dynamic detection range and long scan range effectively. Methods to upgrade the pulse replicator scheme were suggested. (5)The general relation between pulse-front tilt and angular dispersion was deduced for plane waves. The analytical expressions for Gaussian ultra-short pulse beams that possess angular dispersion, spatial chirp and temporal chirp were derived. Then we showed that the equivalence of pulse-front tilt and angular dispersion is valid only for beams without spatial chirp. In the presence of spatial chirp, the combination of spatial and temporal chirp also causes pulse-front tilt. All possible first order spatio-temporal distortions were investigated particularly. (6)The advantages and principle of GRENOUILLE were studied in detail. The model of spectral filter of BBO in GRENOUILLE apparatus was constructed. The simulation results not only reveal the function of a thick crystal acting as a spectrometer intuitively, but also provide the wavelength range and tunability of a GRENOUILLE. A procedure for the design of GRENOUILLE was given, and the schemes of measuring pulse beam’s spatial chirp and pulse-front tilt were studied respectively. |
| 语种 | 中文 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15622]  |
| 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 | 张福领. 高功率超短激光脉冲精密测量技术研究[D]. 中国科学院上海光学精密机械研究所. 2010. |
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