QQ客服 官方微博 反馈留言

题名	强双色激光场中电子动力学控制与相干X射线发射研究
作者	张丽
学位类别	硕士
答辩日期	2009
授予单位	中国科学院上海光学精密机械研究所
导师	李儒新
关键词	高次谐波 阿秒脉冲 激光辅助XUV电离 偏振时间门
其他题名	Control of Electron Motion in Two-Colour High Field and Coherent X-Rays Emission
中文摘要	原子分子中典型的电子运动的时间尺度为几百个阿秒（1 阿秒 =10-18 秒）。目前，一些实验已经证明通过超短超强激光脉冲可以实现对阿秒电子运动的控制。原因在于在强场下，强激光脉冲驱动的非线性过程高度依赖于脉冲的电场，因此人们可以通过控制电场的频率、振幅、位相以及偏振特性来直接控制强场中电子的运动。 获得新波长的相干光源是激光器发明以来激光科学研究的一个重要课题。尤其是对X射线波段相干光源的探索更是经久不息。1987年高次谐波辐射的发现为相干X射线光源的研究注入了一股新鲜血液，并带来了勃勃生机。尤其是近十几年来，世界上各个著名的实验室纷纷加入到强激光场高次谐波辐射研究的队伍中，使高次谐波辐射成为强场物理领域最激动人心的研究课题之一。高次谐波辐射源自隧道电离的电子与母核的再复合过程。在这个过程中，隧道电离高度非线性依赖于激光的电场强度，其对精确控制电子在激光场中的运动起了十分重要的作用。目前，利用周期量级超短超强激光脉冲驱动惰性气体原子产生的高次谐波辐射已经成功地进入了“水窗”波段。强场高次谐波由于其辐射的规律性，为阿秒X射线相干脉冲的产生提供了现实的可能性。 本论文基于强场高次谐波辐射理论，开展了强场中电子动力学控制以及相干X射线发射的研究。我们理论上研究了单个阿秒X射线相干脉冲的产生，实验上产生并测量了阿秒脉冲链，主要成果如下： 1. 理论上提出了一种利用双色偏振时间门激光场与惰性气体氦气相互作用辐射的高次谐波来产生亚100as的单个阿秒X射线相干脉冲的方法。在数值模拟中，我们获得了谱宽为150eV的超连续谐波光谱。对该光谱进行反傅立叶变换，没有经过色散补偿就可以产生脉宽为96as的单个阿秒脉冲。 2. 实验上产生并测量了350as的阿秒脉冲链。基于激光辅助XUV电离的原理，我们测量了随谐波和红外辅助激光之间的时间延迟变化的电子能谱图。通过采用cos函数拟合边带的变化，得到了第17次到第23次这四个谐波的位相。根据测量结果，可以得到这四个谐波相位的线性啁啾率，约为0.0182fs-2，将其反演到时域可以得到脉宽约为350阿秒的阿秒脉冲链。
英文摘要	The typical time scale of electron motion in atoms and molecules is a few hundred attoseconds (1 as =10-18 s). Yet, in several recent experiments it was demonstrated that attosecond electron motion could be controlled by strong short laser pulses. In intense laser field, nonlinear processes generated by strong laser pulses show highly dependence on electric field of the laser, thus by controlling the carrier-frequency, amplitude, phase and also polarization of the electric field of the laser pulses we can take direct control of electronic motion. Since the invention of the laser, to obtain a new wavelength of coherent light source is an important subject of laser science research. Especially the exploration of the coherent light source in X-ray range never stops. In 1987 the High Harmonic Generation (HHG) brought a fresh blood into the research of coherent radiation source in X-ray range, and also vitality. Especially in recent ten years, many world famous laboratories have joined the research of HHG in high laser field, making it one of the most exciting research topics in high field of physics. The HHG is generated from the recombination when electrons return to the ion. In this process, ionization plays an important role for the precise timing of electronic motion in the field because of its strongly nonlinear dependence on electric field. By far, the HHG from the interaction of few-cycle ultra-short strong laser pulses with rare gas atoms has successfully entered the water window. Because of its regularity, the HHG radiation from strong field provides the possibility of reality for the generation of attosecond X-ray coherent pulses. Based on HHG radiation from high field, our thesis focuses on the control of electronic dynamics in high laser field and coherent X-ray emission. We theroretically investigated the generation of single attosecond X-ray coherent pulses and experimentally studied the generation and the measurement of a train of attosecond pulses. The main results are shown as follows: 1. We theoretically proposed a method of generating single sub-100 attosecond pulse with a two-colour time-gating laser field. In our simulation, we obtained a supercontinuum with extremely broad spectrum of 150eV and generated an isolated attosecond pulse with 96as pulse duration without any dispersion compensation. 2. We experimentally generated and measured a train of attosecond pulses with duration of ~350as. Based on laser assisted XUV photoionization, we measured the photoelectron spectrum as a function of the time delay between the IR pulse and the harmonics. By using the cosine function fitting the change of the sidebands, we obtained the phases of the 17th to the 23th harmonics. According to the result of the linear chirp rate of the four harmonics whose value is about 0.0182fs-2, we reconstructed the temporal intensity profile and obtained a train of attosecond pulses with its duration of ~ 350as.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/16514]
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	张丽. 强双色激光场中电子动力学控制与相干X射线发射研究[D]. 中国科学院上海光学精密机械研究所. 2009.

个性服务

查看访问统计

相关权益政策

暂无数据

收藏/分享

除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。