毕业论文移动版

摘要本文研究附加静电场作用下高次谐波的产生过程，探索不同强度的附加静电场对谐波频率、产生效率等的作用。我们采用拟谱分裂算符方法数值求解含时薛定谔方程；并对含时电偶极矩进行傅里叶变换获得高次谐波谱。以激光场电矢量的强度为参照，我们计算了不同强度的附加静电场对高次谐波的影响。计算结果表明：即便外加静电场场较弱，为激光场强度的百分之一，也能使谐波谱上出现偶次谐波；随着静电场强度的增加，例如静电场强度为激光场电场强度的十分之一时，谐波谱出现双平台结构，谐波的截止频率得到延展，但此时谐波强度有所下降；进一步增强静电场强度，则会导致谐波强度的进一步降低，并且此时谐波谱上出现众多分立谐波峰。我们分析了在不同强度的附加静电场作用下，电子的含时电偶极矩以及电子在原子基态的分布几率，结果表明附加静电场会引起更多电子发生电离，同时使得电子被原子核再俘获的几率降低，从而引起谐波强度的降低。50826

 该论文有图16幅，表0个，参考文献12篇。

毕业论文关键词：附加静电场  强激光场  高次谐波  谐波谱   

Effect of the additional static electric field to high-order harmonic generation process

Abstract  In this paper, we study the process of high-order harmonic generation in strong laser field with additional static electric field and explore the impact of different intensity of additional electrostatic field on harmonic frequency and generating efficiency. We numerical solve the time-dependent Schrödinger equation by the pseudo-spectral split operator method and obtain higher harmonic spectrum by Fourier transform the time-dependent electric dipole moment. Taking the electric amplitude of the laser field as a reference, we calculated the impact of different additional electrostatic field intensity on high-order harmonic genertion. The calculated results show that: even though the intensity of the addtional static field intensity is weak, for example, one percent of the laser field intensity, the even-order harmonic appears in the harmonic spectrum; as electrostatic field intensity increasing, for example, the electrostatic field is one-tenth of the laser field intensity, a double-plateau structure can be observed in the harmonic spectrum, and the cutoff frequency of harmonic generation is extended; on the same while, the intensity of the harmonics decreases; further increasing of the intensity of electrostatic field, it will lead to further decrease of harmonic intensity, meanwhile, a multitude of discrete harmonic peaks is produced on the harmonic spectrum. We analyze the impact of different additional electrostatic field on the electron time-dependent electric dipole moment and the probability density of electron in atomic ground state; the results indicate that the additional electrostatic field will induce more electrons ionized and decrease the probability of the electrons re-captured by the nucleus, which will accordingly lead to the reduce of harmonic intensity.

Key Words: additional static electric field  strong laser field  high-order harmonic generation  harmonic spectrum

 目  录

摘要-Ⅰ

Abstract--Ⅱ

目录-Ⅲ

图表清单-Ⅳ 

1 绪论--1

1.1激光技术的发展简介-1

1.2激光场下物质间相互作用的发展-2

1.3强激光场作用下原子的电离-3

1.4高次谐波研究的理论基础-5

2 理论基础--9

2.1含时的薛定谔方程-9

2.2拟谱法求解定态薛定谔方程10

2.3分裂算符法对波函数的时间演化--11

3结果处理与分析--15

3.1入射激光场电矢量随时间的变化14

3.2无附加静电场时的高次谐波谱14 (责任编辑：qin)