【作者】 王秀如；

【导师】 莫育俊；

【作者基本信息】 河南大学 ， 光学， 2003， 硕士

【摘要】 自从发现偶氮分子在光照下能够发生可逆顺反异构这一开创性工作以来，对含偶氮类聚合物及聚合物液晶材料非线性光学等性质的研究日益活跃，是目前国内外非线性光学及其应用研究的一个热门话题。然而，长期以来人们只了解了偶氮材料的双折射和偏振全息等性质，并借此推断偶氮材料具有极大的非线性光学系数。为了进一步定量了解偶氮材料的非线性光学性质，便于与同类非线性光学材料进行比较，本文采用单光束Z扫描技术对新型光学信息存储材料—偶氮分散红聚合物的薄膜样品进行了测量。实验结果表明，该样品的非线性折射率为负值。为消除非线性吸收的影响, 将实验所得数据进行了处理，以有孔Z扫描曲线除以开孔Z扫描曲线。从Z扫描曲线的实验数据处理得到这种新型偶氮分散红聚合物薄膜材料的非线性折射率为：－5.52×10-6cm2/w，其值比常见无机非线性光学材料大8～9个数量级, 是一种很有应用前景的新型光学存储材料。同时，对这种偶氮聚合物薄膜具有大的非线性折射率的物理机制进行了分析。初步认为是一种类似液晶相的集体响应。偶氮分子在线偏振光照射下，薄膜分子变为各向异性。这些类似液晶相的分子是很好地关联在一起的。这种分子的取向对外界扰动的响应是一种集体的效果，所以它们具有很强的非线性响应。同时，作为一种很好的光学应用材料来研究偶氮材料在薄膜状态辅助衬底表面的结构特征，不仅有利于加深对材料物理性质的了解，同时对于优化材料及器件性能，起着不可或缺的作用。因此，本文借助于表面增强拉曼散射光谱（SERS）技术，研究了一种典型的偶氮材料—甲基黄在化学沉积法制备的银岛膜表面的吸附行为和拉曼增强效应。实验结果显示，甲基黄在银表面的状态被判断为：结构式左端的两个甲基与银镜衬底发生物理吸附，向右依次成一定角度远离银镜的表<WP=3>面，在第一个苯环处发生弯曲，氮－氮双键与作为基底的银表面基本平行，在第二个苯环处再次发生弯曲，第二个苯环相对与银镜表面垂直，它们之间为物理吸附。最后，为了检验偶氮材料作为光学存储材料的优良特性，在前人工作的基础上我们对偶氮材料的光致双折射测量光路进行了改进。初步的理论推导表明，改进后的光路会得到更加精确的实验值。同时，本文对偶氮材料进行了偏振全息实验。研究发现：该样品具有显著的偏振敏感特性。并在其中记录了由两束相互正交线偏光形成的偏振全息图，衍射效率达19.3％。样品多次使用后没有出现明显的疲劳现象，说明该材料是一种比较理想的偏振全息记录材料。更多还原

【Abstract】 Since the starting work that azo molecule has reversible cis-trans structure changing, Study on the polymer possessing azobenzene and polymer is booming increasingly liquid crystal, these days it is an attractive topic of nonlinear optics and its application. But in the very long time, people realized only the birefrection and polarized photograph character and so on, and that azo material has very large nonlinear optical coefficient is deduced by this way. Now for the purpose of realizing the nonlinear optical character quantificationally and comparing with the same kind of nonlinear optical materials expediently, a new type of optical storing material, the film sample of azobenzene disperse red polymer was measured by using the single beam Z-scan technique. The experimental results show that the nonlinear refractive index of the sample is a negative value. For eliminating the influence of nonlinear absorption, the Z-scan curve with an aperture was treated with the Z-scan curve without the aperture. The nonlinear refractive index of this type of azo polymer film was determinated as -5.5210-6cm2/w according to the experimental data of Z-scan curve. The value of azo polymer film is larger 8~9 scales than the common inorganic materials. This material would have a very good prospect in the application of optical storage. At last, the reason of large nonlinear refractive index in this material is discussed. It is considered a collective response just like the liquid crystal through pilot study. Under the irradiation of linear polarized beam, molecule of film has been anisotropic. These molecules liked liquid crystal phrase are linked together commendably. This molecules’ response to outside trouble is a collective effect, for this reason they possess very large nonlinear response.<WP=5> At the same time, as an excellent optical applied material, study of station and structure of azo film on the surface of accessorial underlay is propitious to realize material’s physical character deeply, and has indispensable function for optimizing the quality of material and apparatus. As a result of this, methyl yellow as a typical azo materiel has been studied by SERS spectrum technology, the enhanced Raman peak and adsorption mechanism of methyl yellow has been investigated on the surface of the rough silver that was made by the way of chemical sediment. As the experiment’s result showing, adsorption station of methyl yellow is considered that: two methyls in the left of structure have physical adsorption with the surface of the rough silver. In turn the right is away from the surface of the rough silver. The structure bends at the place of the first phenyl. Twin-bend of nitrogens is almost parallel to the surface of the rough silver. The structure bends again at the place of the second phenyl. The second phenyl is vertical to the surface of the rough silver, there are physical adsorption between them.At last, for the purpose of azo property as an optical storage material the setup of measuring photo-induced birefraction of azo has been bettered on the base of primary work. Primary academic deduction shows that the improved setup can gain more accurate experimental result. At the same time, polarized holography experiment of azo material has been done, the sample has been found prominent polarized sensitive character. And polarized holography image that has been produced using two vertical linear polarized beams has been recorded, its diffractive efficiency is 19.3%. The sample has not presented evident fatigue, this material has been proved an ideal material for recording polarized holography.更多还原