摘要高次谐波是在原子或分子和强激光场相互作用过程中产生的，是强场物理中一个很重要的研究方向，具有广阔的应用前景，尤其是用于产生超短脉冲，本文主要围绕高次谐波开展了一些模拟研究。65269

首先简单讲述了强激光场中产生高次谐波的基本原理，主要包括几种电离机制、经典的“三步模型”以及单原子响应模型（强场近似模型和单电子近似模型）等；其次介绍了谐波在宏观介质中的传播模型；也简要阐述了数值计算方法和LZH-DICP并行程序，以及量子轨道和时频分析方法。最后是本次论文的主要工作，利用LZH-DICP并行程序计算模拟了中红外波段1600 nm~2400 nm的He原子体系高次谐波的产生及其传播效应，并通过调节参数优化得到较为理想的高次谐波，讨论双色场的相位差影响，并结合时频图给出了相应的解释。

毕业论文关键词：高次谐波 单原子响应模型 传播效应 中红外激光 LZH-DICP

毕业设计说明书（论文）外文摘要

Title   High-Order Harmonic Generation and Propagation Effects 

 in Mid-Infrared Laser Fields 

Abstract

High order harmonic is generated during the interaction between atoms/molecules and intense laser field, and it is an important research area in strong-field physics, which has a broad application, especially for generating ultra-short laser pulses. The study of this paper focuses on the numerical simulation of high order harmonic.

First of all, this paper presents the fundamental principle of the high order harmonic generation in strong laser field, including several mechanisms of ionization, classic “three-step” model, and single atom response models (strong field approximation and single active electron approximation); then provides the model of the laser propagating in macromedia. In addition, this paper also introduces the computer code, LZH-DICP, as well as quantum path and time-frequency analyses. For comparison, the mid-infrared laser wavelength is selected as 1600 nm~2400 nm, which is used in numerical calculations. The last part is the main work in this paper. By using the LZH-DICP program, we investigate the high order harmonic generation and the propagation effects of He atoms in mid-infrared laser field. Through adjusting laser parameters, we obtain ideal high order harmonic spectra. We also discuss the effects of phase difference in a two-color field, and give appropriate explanations combining the time-frequency graphs.

Keywords: High Order Harmonic, Single Atom Response, Propagation Effects, Mid-infrared Laser, LZH-DICP

目  次

1 绪论 1

1.1 高次谐波研究背景及意义 1

1.2 高次谐波研究进展及现状 2

1.3 论文主要工作及章节安排 5

2高次谐波产生理论模型 6

2.1电离机制 6

2.2三步模型 7

2.3单原子响应模型 8

3高次谐波宏观传播模型 11

4 数值模拟计算 12

4.1基本理论与LZH-DICP并行程序 13

4.2量子轨道与时频分析 14

4.3驱动激光场的表示 15

5计算结果与分析 15

5.1 单色激光场 15

5.2 双色激光场 21