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题名	原子高次谐波相位匹配与分子高次谐波角度分布问题的研究
作者	芦慧
学位类别	硕士
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	李儒新 ; 刘鹏
关键词	高次谐波，相位匹配，分子取向，分子动力学
其他题名	The investigation about phase matching of atomic high harmonic generation and angular distribution of molecular high harmonic generation
中文摘要	超短超强激光与原子、分子相互作用产生高次谐波（HHG）是获得相干X射线辐射的有效途径，对原子分子光谱学，等离子体物理和相干成像等应用具有重要意义，是近十年来热门的基础研究课题。其中高次谐波辐射强度的提高常采用相位匹配或准相位匹配技术；而对分子高次谐波的角度分布的研究在分子轨道重构成像中扮演着重要的角色。本论文从实验和理论上研究飞秒强激光与超声喷气靶相互作用下原子高次谐波相位匹配问题，和强场近似模型（SFA）对分子高次谐波角度分布适用性问题，取得了一下的研究成果： 1. 实验研究了超声喷射条件下氖原子气体产生高次谐波的相位匹配条件，通过改变气体密度、入射激光能量和聚焦位置，得到了60~70eV范围内增强的高次谐波； 2. 以上述实验结果为依据，从理论上研究超声喷气靶装置产生高次谐波的相位匹配问题。研究发现，随着激光功率密度的提高，等离子体在其相位匹配过程中起主导作用，并引起高次谐波光谱的蓝移展宽；指出利用其光谱变化可以实现高次谐波的波长调谐。 3. 实验和理论上研究了CO2分子高次谐波的取向依赖关系，并对强场近似模型在分子高次谐波研究中的适用性进行了检验，得出结论：用SFA来描述分子高次谐波的角度分布情况，定性分析是大致符合的，而定量分析误差比较大。
英文摘要	High harmonic generation (HHG) driven by intense ultrafast lasers provides a way to produce spatially and temporally coherent light radiation down to the extreme-ultraviolet and X-ray regime, which is increasingly used in applications such as atomic and molecular spectroscopy, plasma physics and coherent imaging and thus has been widely investigated in the past two decades. Among those investigations, great efforts have been made either to increase the harmonic conversion efficiency through the phase matching or quasi-phase matching methods or to retrieve molecular orbital structures from HHG in aligned molecules. In this thesis, experimental and theoretical studies have been carried out on phase matching condition of HHG in a supersonic gas jet, and on angular distributions of HHG from aligned CO2. The research progresses in this thesis are shown as follows: 1. Phase matching condition of HHG from a supersonic neon gas jet has been investigated experimentally. By optimizing the phase matching condition through tuning the gas density, the incident laser energy and the focus position, the enhanced HHG in the region of 60∼70eV has been selected. 2. Based on the above experimental results, we analytically study the phase matching issue of HHG from a supersonic gas jet. We find that with the increase of laser intensity, plasma plays a leading role in the phase matching process, and causes blue shift and broadening of the HHG spectra, which provides a method for fine tuning of harmonic wavelength. 3. The angular distributions of harmonic emission from aligned CO2 are explored experimentally and theoretically, and the validity of Strong Field Approximation (SFA) model in the molecular HHG is therefore studied. The study shows that for describing the angle distribution of HHG from molecules, SFA model is roughly consistent with qualitative analysis, while quantitative analysis is different.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/16687]
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	芦慧. 原子高次谐波相位匹配与分子高次谐波角度分布问题的研究[D]. 中国科学院上海光学精密机械研究所. 2010.

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