The Number Of Weak Light Nonlinear Optical Effects In The Photosensitive Material

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.