非共线宽带OPCPA中非共线角与放大光谱的研究
文献类型：学位论文
| 作者 | 马林 |
| 学位类别 | 硕士 |
| 答辩日期 | 2014 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 梁晓燕 |
| 关键词 | 超快光学 YCOB OPCPA 非共线角 自动化准直 |
| 其他题名 | Non-collinear angle measurement and Amplified spectrum research for non- collinear broadband OPCPA |
| 中文摘要 | 经过近几十年的发展，超强超短激光系统的峰值功率能达到太瓦（1012W）甚至拍瓦（1015W）量级，聚焦后激光的峰值功率能够达到1021 W/cm2-1023W/cm2。输出的超短超强脉冲激光为众多科研领域提供了所需要的前所未有的极端物理条件和实验手段，比如，激光尾波场粒子加速、高次谐波的产生和快点火激光核聚变、超快X射线辐射等等。对于大部分的物质与强场激光相互作用过程来说，超短超强脉冲激光的峰值功率密度起着决定性的作用。而脉冲激光的峰值功率密度主要由焦斑大小、激光单脉冲能量以及脉冲宽度所决定。因此，获得窄脉冲宽度和高脉冲能量的超高功率激光是超短超强脉冲激光研究领域的热点。 目前，超短超强脉冲激光放大的主要实现方法有两种：啁啾脉冲放大（Chirped Pulse Amplification，CPA）和光学参量啁啾脉冲放大（Optical Parametric Chirped Pulse Amplification，OPCPA）两种放大方式，其中CPA技术相对更为成熟，其输出的脉冲激光性能稳定，能量转换效率高;但是在放大过程中，由于使用的大口径放大介质会产生很强的自发辐射放大(Amplified Spontaneous Emission, ASE) 以及增益窄化效应，从而限制了其发展应用；而OPCPA技术由于在放大过程中，使用非线性晶体进行放大，从而避免了自发辐射放大现象以及增益窄化效应，其输出的脉冲激光则具有单程增益高、可调谐范围大、增益带宽宽、热效应较好、B积分较小、放大信号性噪比高等优点，成为一种更加具有强劲发展潜力的超短超强脉冲激光放大技术。 OPCPA有两种实现方式：共线的OPCPA与非共线的OPCPA，相对共线的OPCPA而言，非共线的CPCPA能支持更大的增益带宽，所以大部分的OPCPA系统均采用非共线结构。而在非共线结构的OPCPA过程中，非共线角以及相位匹配角对整个放大过程有很大的影响。 本论文主要围绕在非共线YCOB-OPCPA中，非共线角与相位匹配角对放大光谱的影响进行研究，并提出一种精确测量并有效调节非共线角的方法，最后提出一套激光系统自动化准直的方案。主要研究成果如下： 1. 就非共线角与相位匹配角对527 nm泵浦800 nm YCOB-OPCPA放大光谱的影响进行了理论仿真模拟，研究发现基于YCOB-OPCPA的放大光谱对相位匹配角和非共线角的变化均比较敏感，当相位匹配角或非共线角有微小变化时，增益光谱将会出现中心波段漂移和窄化现象，但当非共线角在2.80°到2.91°之间变化时，总能找到一个理想的相位匹配角与之匹配，满足带宽大于80 nm的宽带OPCPA放大。 2. 由于非共线角对OPCPA过程的十分重要，提出了一种精确测量并有效调节非共线角的方法。该方法基于高精度的CCD采集光斑图像，利用Matlab对光斑图像进行分析处理，得出光斑图像中心在CCD上的坐标位置，利用简单的数学原理以及简易的实验设计对非共线角进行精密测量并精确调节。 3. 提出了一套激光系统自动化准直的方案，该方案以LabVIEW为调节控制平台，协调相关软件进行分析处理，并利用驱动控制器对带步进电机的调整镜进行光路准直。 |
| 英文摘要 | After decades of development, peak power of ultra short and ultra-intense laser system can has achieved the terawatt (1012W) even pet watt (1015W) level, the focused laser peak power has been up to 1021 W/cm2-1023W/cm2. The output of the ultra short and ultra-intense laser pulse provides hitherto unknown extreme physical conditions and experimental means to many areas of research, for example, laser Wakefield acceleration of particles, high harmonic generation and fast ignition laser nuclear fusion, ultrafast X ray radiation etc.. For most of the material and the strong field laser interacting processes, the ultra short and ultra-intense pulse laser peak power density plays a decisive role. While the laser pulse peak power density is mainly determined by focal spot size, pulse energy and pulse width. Therefore, achieving ultra high power laser with narrow pulse width and high pulse energy is a hot research field of ultra short and ultra-intense laser pulse. At present, the main method of ultra short and ultra-intense pulse laser amplification has two ways: chirped pulse amplification (CPA)and optical parametric chirped pulse amplification ( OPCPA), among them, CPA technology is relatively mature, the output pulse laser is with stable performance, high energy conversion efficiency; But in the amplification process, due to the use of large diameter amplifying medium will produce very strong Amplified Spontaneous Emission(ASE) and the gain narrowing effect, thus limiting its development and application; During amplification, the OPCPA technology makes use of nonlinear crystal, thus avoiding the amplified spontaneous emission and gain narrowing effect, the output pulse laser is with high gain, large tunable range, gain bandwidth, better heating effect, small B integral, better signal to noise ratio etc., and it becomes a method of the ultra short and ultra-intense pulse laser amplification which has more potentially powerful development . As for OPCPA, there are two ways: collinear and non-collinear OPCPA, comparing to collinear OPCPA, non-collinear CPCPA can support better gain bandwidth, so most of OPCPA systems adopt the non-collinear structure. In the process of OPCPA no collinear structure, non-collinear angle and phase matching angle has a great influence on the amplification process. This thesis mainly focuses on the study of the non-collinear angle and phase matching angle impacting the amplification spectrum in the process of non-collinear YCOB-OPCPA, and we propose a kind of accurate measurement and adjustment method for the no collinear angle；At the same time ，in order to guarantee the stable operation of OPCPA laser system, we finally put forward a set of automated laser collimation system scheme. The main research results are as follows: 1. We do the theoretical simulation of how non-collinear angle and phase matching angle impact the 527 nm pumped 800 nm YCOB-OPCPA amplification spectrum , the study finds that the amplification spectrum of YCOB-OPCPA is sensitive to the phase matching angle and the non-collinear angle’s changes, when the phase matching angle or non-collinear angle has small changes, the gain spectrum will appear the center wavelength shift and narrowing effect, but when the no collinear angle is between 2.80 ° and 2.91 °, there will always find an ideal phase matching angle ,meet the more than 80 nm OPCPA broadband bandwidth amplification. 2. Due to the effect of no collinear angle on OPCPA process is very important; This paper proposes a precise and adjustment method for non-collinear angle. The method is based on the CCD acquire facula image with high accuracy, using Matlab to analyze the spot image; Finding out the coordinate position of facula image center on CCD, using the simple mathematical principle and the simple experiment design to precisely measure and adjust non-collinear angle . 3. We put forward a scheme of automatic laser collimation system, the LabVIEW is used as control platform to coordinate the related software for analysis and processing, the drive controller is used to control the mirror with stepping motor for alignment adjustment. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16852]  |
| 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 | 马林. 非共线宽带OPCPA中非共线角与放大光谱的研究[D]. 中国科学院上海光学精密机械研究所. 2014. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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