光敏材料中若干弱光非线性光学效应研究

【作者】 李威；

【导师】 许京军；

【作者基本信息】 南开大学 ， 凝聚态物理， 2009， 博士

【摘要】 上世纪60年代,激光的发明开拓了光学领域的一个全新分支—非线性光学。随后,弱光非线性光学逐渐从非线性光学中细分出来,成为一个重要的研究领域。各种具有弱光非线性的材料已经广泛应用于光存储、信息处理、信息传输等各个方面。进入本世纪,随着材料科学和交叉学科的发展,聚合物材料正在进入弱光非线性光学领域,并发挥着越来越重要的作用。有机玻璃作为聚合物非线性光学材料中极其重要的一种,正在被越来越多的研究者关注。本文将以紫外敏感的有机玻璃为主要研究目标,对其反应机制和光致折射率变化性能做系统优化和深入探索。同时,尝试把量子力学领域的态密度理论引入到低折射调制的全息存储材料中,为研究低折射率调制材料的弱光非线性光学性质开创新的思路。本文第一章介绍了弱光非线性光学及聚合物非线性材料的特点和性质,进而给出本文的研究内容和思路。第二章介绍了制备紫外光敏有机玻璃的反应原理和详细过程。还对其光敏反应机制进行了研究,建立了光敏反应模型。第三章,通过二波耦合实验测得了紫外光敏有机玻璃光致折射率变化的相关参数。还对光致聚合非局域性引起的复光栅的相位移进行了研究,得到了有机玻璃中记录微结构的更详细的信息。为有机玻璃的弱光非线性应用提供了实验基础。第四章中,在弱光非线性材料中观测到了周期结构对荧光增强的调制效应,尝试把量子力学中常用的态密度理论引入低折射率调制的弱光非线性材料的实验结果分析中。具体方法是借助于重铬酸盐明胶薄膜的光敏感性,研究了低折射率调制的全息存储材料中光学周期结构对自发辐射的调制,并与态密度重新分布理论得到的结果进行对比,发现两者符合的很好。这在一方面证明了态密度理论在处理凝聚态物理领域问题的强大威力,也为研究光学材料的弱光非线性性质开辟了一个新的研究方法和思路。第五章中对本文主要的研究成果进行了总结,并对以后的工作设想做了简单阐述。更多还原

【Abstract】 In 1960’s, nonlinear optics came into research as a branch of optics with the invention of lasers. The observation of photorefraction at weak light opened a new field of nonlinear optics. Many nonlinear optics materials with weak light were widely studied and used in optical storage, information processing, communication, and so on. In this century, with the rapid development of materials science and interdisciplinary communication, nonlinear polymeric materials have been paid more and more attention.As one of the important nonlinear optical polymer materials, Polymethyl methacrylate (PMMA) has attracted many researchers to explorer its application in nonlinear optics with weak light. This dissertation deals with the reaction mechanics and optimization of the UV-light sensitivity, and also tries to introduce the redistribution theory of density of states to holographic media; this would give a new method to develop the application of nonlinear optics materials with relative low refractive index contrast.In chapter one, the characteristics of the nonlinear optics at weak light and polymeric materials are given. The main research subject PMMA and the outline of the dissertation are also presented.In chapter two, the fabrication detail and the reaction mechanics are introduced. The light polymerization model is built according to the research results of the absorption.In chapter three, the parameters of light induced change of refractive index and absorption are measured. The detail of photo-polymerization is gotten by studying the phase shifts of the holographic gratings which come from the non-local photo-polymerization. The results of this chapter prove that PMMA has perfect optical characters and is optimistic to use in many optics fields.In chapter four, the density of states is successfully introduced to analyze the redistribution of the photoluminescence in holographic media - dichromated gelatin, although it has a relatively low refractive index change. This successful attempt proves the power of density of state theory in solving problems in condensed matter physics and gives us a new way to develop the application of materials with low refractive index contrast in nonlinear optics with weak light.In the last chapter, all the results of this dissertation are listed again and the further work and the possible application of PMMA and density of state theory are also discussed.更多还原