论文总字数：17818字

摘 要

本文属于实验研究，针对二维铁电体超晶格结构的倍频空间输出给出测定，确定其中达到准相位匹配的光强变化的空间位置，验证Ewald球在研究准相位匹配的匹配模式下的弹性散射锥形辐射的光强变化中所起的作用。

在第一章绪论部分对本文的研究背景进行了介绍，并就本文要研究的课题简要介绍了研究目的、思路和技术方法。

第二章对非线性光学、光子晶体、超晶格结构的定义进行了介绍，简要的介绍了非线性光学中的变频效应，并对非线性振幅的光学倍频原理进行了详细说明。

第三章着重讲述了非线性光学中准相位匹配的相关理论，并介绍了本文研究弹性散射准相位匹配过程所使用的方法——矢量球壳法（Ewald法），理论计算了非线性晶体样品转动时其内倍频光的演化规律和倒空间的变化情况，并给出形成光强极值点时样品的具体转动角度。

第四章主要讲述本课题相关的实验准备，介绍了本文的样品——铁电体材料中的钽酸锂（LiTaO₃）的制备方法、实验光路的搭建，包括光源、相关的光学器件及其作用、实验环境、实验思路等。最后列出了实验现象、实验结果与理论计算的数据进行比对，总结。

关键词：非线性光子晶体 准相位匹配 矢量球壳法 钽酸锂

Extreme values of light intensity in multiple second harmonic (SH) elastic scattering

Abstract

This work is an experimental research, by studying artificially structural ferroelectric materials, the spatial phenomena of the output second harmonic are determined. The Ewald sphere in the study plays a main role in the study of second harmonic intensity variation of quasi-phasematching processes. By this method, the quasi-phase-matched cone beam is investigated.

The background of this paper is introduced in the first part of this thesis, and the purpose, thoughts and technical methods of this research are briefly discussed.

The second chapter presents the notions of nonlinear optics, photonic crystals and superlattice structures. It acquaints the readers with the phenomena of nonlinear optical frequency conversion and explains the principle of optical frequency multiplication with nonlinear amplitude.

The third chapter focuses on the quasi-phasematching theory in nonlinear optics and introduces the method used in this thesis to study the quasi-phasematching process of elastic scattering-the vector spherical shell method (Ewald method). Theoretically deduced the changing pattern of the frequency-doubling and the reciprocal space of the ferroelectric sample when it rotates, and theoretically calculated the specific rotation angle of the sample when forming the extreme points of light intensity.

The fourth chapter mainly describes the preparations of this experiment, the fabrication of the LiTaO3 sample in this thesis, and the construction of the optical installation, including the light source, related optical elements and their effects, experimental environment and design, etc. Finally, the experimental results and data are listed. The captured images are used to show the discovered phenomena. The measured data is compared with theory, and the probable defects appearing in the experimental results are summarized.

Keywords: Nonlinear photonic crystals; Quasi-phasematching; Vector shell method; LiTaO₃ (LT)

目录

摘 要 2

ABSTRACT 3

第一章 绪论 5

1.1 研究背景 5

1.2研究目的、思路和技术方法 5

第二章 非线性光学 7

2.1非线性光学 7

2.1.1非线性光学的介绍 7

2.1.2光学的变频效应 7

2.2光子晶体 7

2.3介电体超晶格材料 8

2.4非线性振幅的光学倍频原理 9

第三章 弹性散射准相位匹配锥形辐射 10

3.1准相位匹配理论原理 10

3.2 矢量球壳法研究弹性散射准相位匹配 12

3.3 矢量球壳法（Ewald球壳） 14

3.3.1一维样品中准相位匹配锥形辐射 14

3.3.2 一维样品中准相位匹配锥形辐射 15

3.3.3实验样品旋转角度理论计算 15

第四章 二维弹性散射准相位匹配实验 21

4.1实验材料 21

4.1.1钽酸锂（LiTaO₃）晶体 21

4.1.2实验样品的制备 21

4.2实验装置 22

4.3实验结果 23

结语 29

参考文献 30

致谢 32

第一章 绪论

1.1 研究背景

二十世纪六十年代前后，激光被创造并用做研究的设备，激光频率转换^[1] 逐渐转变为非线性光学^[2,3,4]方面的首要探究目标。其中的课题之一，便是使用二次谐波衍生其他频率的激光。

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