Research Initiation Award: Nonlinear Optical Materials Via Sol-Gel Processing

光学二次谐波的发现 1961年，晶体的出现推动了该领域的快速发展。 非线性光学 非线性光学材料 其光学性质取决于光的强度 事件发生在他们身上。 非线性可以是以下形式： 强度相关折射率或可饱和折射率 吸收 这些材料具有实际应用， 电信、数字计算机和激光聚变。 他们 有潜力成为未来的光学半导体 其可以在两到三个数量级的频率下工作， 比目前的半导体技术更先进。 的 PI计划探索形成商业上可行的非线性 使用溶胶-凝胶技术的光学材料。 溶胶-凝胶 该方法是一种制备无机膜的方法， 由有机金属单体 化合物. 该过程类似于分步反应 在有机体系中的聚合，其中单体是 通常是金属醇盐如四甲氧基硅烷。 这些 反应在室温下，在常见的溶剂中进行， 醇盐和水，并使用酸或碱催化剂。 溶胶-凝胶法将用于制备新型非线性光学薄膜 通过聚合改性醇盐单体的光学材料 RSi（OR '）3形式的化合物，其中R表示有机 功能性被证明具有高度非线性 易感性 工作将集中在R-基团， 主要是取代的苯、吡啶和偶氮染料。 市售醇盐和定制醇盐 作为这项研究的一部分，将进行研究。 薄膜和单片材料将被制成。 到 便于观察二阶非线性效应， 有机官能团的偶极将使用 电晕极化 二阶和三阶 起始材料的相容性以及 将使用二次谐波对聚合材料进行评估 产生和四波混频。 力量， 耐化学性和耐环境性，以及热稳定性 还将确定薄膜和散装材料的厚度。

The discovery of optical second harmonic generation in crystals in 1961 spurred rapid progress in the field of nonlinear optics. Nonlinear optical materials are materials whose optical properties depend upon the intensity of light incident upon them. The nonlinearity could be in the form of an intensity dependent refractive index or a saturable absorption. These materials have practical applications in telecommunications, digital computers, and laser fusion. They have the potential to become future optical semiconductors which can operate at frequencies two to three orders of magnitude higher than current semiconductor technology. The PI plans to explore formation of commercially viable nonlinear optical materials using the sol-gel technique. The sol-gel process is a means for producing inorganic films and monolithic structures from organo-metallic monomeric compounds. The process is analogous to step reaction polymerizations in organic systems where the monomer is usually a metal alkoxide such as tetramethoxysilane. These reactions are run at room temperature, in a common solvent for alkoxide and water, and using either an acid or base catalyst. The sol-gel process will be used to produce new nonlinear optical materials by polymerizing modified alkoxide monomers of the form RSi(OR')3 where R represents an organic functionality demonstrated to have a high nonlinear susceptibility. Work will focus on R-groups which are primarily substituted benzenes, pyridines and azo dyes. Commercially available alkoxides and custom alkoxides synthesized as part of this research will be investigated. Thin film and monolithic materials will be made. To facilitate the observation of second-order nonlinear effects, the dipoles of the organic functionality will be aligned using corona poling. The second-order and third-order susceptibilities of the starting materials as well as the polymerized materials will be assessed using second harmonic generation and four-wave mixing respectively. The strength, chemical and environmental resistances, and thermal stability of the film and bulk materials will also be determined.