QQ客服 官方微博 反馈留言

题名	中红外周期量级激光脉冲载波-包络相位的物理效应研究
作者	龚成
学位类别	博士
答辩日期	2013
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	中红外激光，载波-包络相位，高次谐波，相位匹配， 隧穿电离，光丝，能量交换
其他题名	Physical effects of carrier-envelope phase of few-cycle mid-infrared laser pulses
中文摘要	随着光学参量放大技术和脉冲压缩技术的发展，实验室已经能在中红外波段产生周期量级载波-包络相位稳定的激光脉冲。周期量级激光脉冲的电场在脉冲包络内快速变化，因此，在与物质相互作用过程中脉冲的载波-包络相位扮演着重要的角色。同时，当激光脉冲的中心波长到达中红外波段时，气态或固态介质中的电离过程更容易进入隧穿电离区域，而隧穿电离对激光电场的指数依赖激发了亚光周期的动力学过程。周期量级激光脉冲与物质相互作用过程中的载波-包络相位效应已经成为近几年来光学领域最前沿的课题之一。 本文是利用实验室搭建的三级光学参量放大器产生的1.75μm/12fs/700μJ激光脉冲，分别研究了惰性气体高次谐波产生过程中和透明固体介质隧穿电离过程中的载波-包络相位效应，以及空气中成丝过程中的能量交换。主要内容和创新点包括： 1. 研究了中红外周期量级激光脉冲与氖气相互作用产生高次谐波过程中的载波-包络相位效应。在某些特殊的载波-包络相位下，能产生一个宽的XUV光“超连续谱”。通过数值模拟发现，该超连续谱分成两个可区分的区域，一个位于平台区，另一个位于截止区。它们分别产生于激光脉冲相邻的两个半周期内。而且，平台区的超连续谱来自长轨道的贡献，这是中红外驱动光源产生高能谐波光子过程中新的相位匹配机制。 2. 研究了透明固体介质隧穿电离过程中的载波-包络相位效应。用谱干涉的方法测量伴随成丝过程产生的超连续谱相位，发现该相位随CEP发生周期性非线性变化。这是直接观测到透明固体介质中的强场亚周期电离动力学过程。 3. 研究了周期量级激光脉冲在空气中成丝过程中的能量交换过程。在实验上，激光脉冲没有啁啾。改变两束光之间的延时，能量交换的方向不仅随延时周期性的变化，周期为激光的振荡周期,而且随不同光谱成分而改变。由于周期量级激光脉冲有较宽的光谱，第一次在实验上观测到能量交换过程中的光谱精细结构。推广平面波耦合理论，考虑激光的脉冲包络效应的模拟结果与实验结果在定性上是一致的。发现该能量交换方向的周期性改变源自空气分子的拉曼效应的贡献。
英文摘要	With the devolepment of ultrashort laser technology, such as optical parametric amplification (OPA) and pulse compression, few-cycle mid-infrared laser pulses with stabilized carrier-envelope phase (CEP) has been generated in laborary. The electric field of few-cycle laser pulses varies quickly under the carrier envelope. So during the interaction of few-cycle intense laser pulse with matter, the CEP of the laser pulse plays a crucial role. Meanwhile, the central wavelength of laser pulse has been expanded to mid-infrared region, the ionization in gasseous and solid medium can easily reach the region of tunneling ionization. The exponential dependence of ionization probability on electric field opens the door to the sub-cycle dynamic process. In recent years, study on the CEP effects during the interaction of few-cycle intense laser pulse with matter has become one of the advanced projects in the field of optics. The work of this thesis research all use 1.75 μm/12 fs/700 μJ laser pulses generat -ed by a home-made optical parametric amplifier. The CEP effects in the process of high-order harmonic generation and tunneling ionization in transparent solids and the energy exchanging during filamentation in air were studied. Main results and innovative points are listed as following: 1. We investigate the CEP effects during the high-order harmonic generation in Neon atoms driven by few-cycle mid-infrared laser pulses. At some specific CEP, a broad “supercontinuum” of the XUV spectrum can be obtained. Two distinct continuous spectral regimes are found by numerical simulation, which come from two adjacent half cycles of the laser pulse. One of the two continuous spectral regimes is in the cutoff regime and the other is in the plateau regime, which comes from the contibution of long path. This is a new phase matching mechanism for high photon energy harmonics generated by mid-infrared laser pulse. 2. We investigate the CEP effects of tunneling ionization in transparent solids. The phase variation of the accompanying supercontinuum (SC) emission with filamentation at different CEPs of laser pulses can be measured by means of spectral interference technique. This is a direct manifestation of the strong field sub-cycle ionization dynamics in transparent solids. 3. We investigate the energy exchanging between few-cycle laser filaments in air. In our experiment, the laser pulses are chirp free. When the time delay between the two paths is changed, the direction of energy exchange not only oscillates with a period of optical cycle but also varies with the spectral components. In addition, benefitting from the broadband spectrum of few-cycle laser pulses, fine spectral structure is observated for the first time. The simulation results obtained by using a generalized two-beam coupling model agree well with the experimental results. The fine spectral structure comes from the effects of the Ramam effect of air molecules.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/15727]
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	龚成. 中红外周期量级激光脉冲载波-包络相位的物理效应研究[D]. 中国科学院上海光学精密机械研究所. 2013.

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。