摘要强激光与原子或分子相互作用产生的高次谐波，是获得单个阿秒脉冲的重要途径。本文通过数值计算的办法求解了经典理论下电子在激光场中的牛顿运动方程，用强场近似的方法求解单个氦电子在强激光场作用下的含时薛定谔方程，采用数值计算和理论分析相结合的办法，研究了两色激光（基频激光和二阶谐波、或三阶谐波相干叠加）中产生的高次谐波。通过半经典分析，扫描相位差得到最优双色激光场（基频激光和二阶谐波叠加场）参数的组合，扩展高次谐波的截止位置，展宽平台区，叠加平台区的连续高次谐波谱，产生脉宽仅为60as的阿秒脉冲。同时，通过叠加基频激光和三阶谐波，在特定相位下，拓宽了高次谐波平台区，提高了高次谐波效率。本文的研究成果，为实验上利用双色场来产生单个阿秒脉冲和改善高次谐波效率提供了有益的参考。87548

毕业论文关键词  高次谐波  三步模型  阿秒脉冲  小波变换 

毕业论文外文摘要

Title        Generation of single attosecond pulse by driving Atoms in multi-color laser pulses                                                 

Abstract High-order harmonic generation (HHG) can be emitted from atoms and molecules driven by the interaction of intense laser field, which is an important way to obtain single attosecond pulse。 In this paper, the Newton motion equation of electron in the laser field is solved by numerical calculation, and the time-dependent Schrödinger equation (TDSE) of a helium atom in the laser field is solved by strong-field approximation (SFA)。 The harmonics generated in a two-color laser field (coherent superposition of fundamental frequency laser and two or three order harmonic) is investigated with the method of combining numerical calculation and theoretical analysis。 Based on semi classical analysis, the optimal combination of parameters of a two-color laser field (coherent superposition of fundamental frequency laser and two or three order harmonic) is obtained by scanning phase difference。 And the cutoff position of high-order harmonic is extended, the plateau region is widened。 The continuous high-order harmonic spectrum of the superimposed plateau region produces a pulse duration of only 60as。 At the same time, the superposition of the fundamental frequency laser and the three order harmonic, in a specific phase, broadens the HHG plateau region and improves the efficiency of HHG。 The research result of this paper is to provide a useful reference for the experimental use of the two color field to generate a single attosecond pulse and improve the efficiency of harmonic。

Keywords  high-order harmonic, three-step model, attosecond pulse, wavelet transform

目   次

1  引言  1From+优 尔-论+文W网www.youerw.com 加QQ752018`766

1。1  强激光技术的发展及影响  Y

1。2  高次谐波的研究进展  Y

1。3  阿秒脉冲的主要应用  Y

1。4  本文主要工作  Y

2  理论模型与方法  Y

2。1  经典三步模型  Y

2。2  含时薛定谔方程  Y

2。3  强场近似  Y

2。4  小波变换  Y

3  计算结果与分析  Y

3。1  经典计算  Y

3。2  量子计算  Y

3。2。1  单色和两色激光的电场  Y

3。2。2  高次谐波谱  Y

3。2。3  阿秒脉冲的产生  Y

3。2。4  基频激光和三阶谐波叠加场  Y