Nonlinear Optical Properties of Small Grain Composites (Joint Research Effort)

提出了一项为期三年的理论计划，研究镶嵌在玻璃或悬浮在胶体溶液中的诺贝尔金属颗粒（金、银、铜）和半导体颗粒（Cd SexS1-x）的非线性光学性质。研究还将集中在粒子的尺寸分散、形状变化和聚合物涂层上，以增强光学非线性。该项目涉及这些颗粒中量子受限载流子动态特性的理论表述和介电函数的计算。本文将建立一种广义有效介质理论，以获得含金属或半导体颗粒和介电主体材料的复合材料的整体介电响应。通过对复合介质的数值模拟，对广义有效介质理论进行了验证。由此得到的介电函数将用于研究电磁波在介质中的空间传播。我们的描述将包括横向模式和正向和反向波传播，以获得对材料的真实分析。研究人员将研究电磁波的吸收和反射，以及多波混频。这些材料的实验数据将根据这些介电函数进行分析。光学双稳性和光学相位共轭现象也将在复合材料中进行研究。该项目有望对这些材料在非线性光学器件中的应用进行现实评估。

A three year theoretical program to study nonlinear optical properites of nobel metal grains (gold, silver and copper) and semiconductor grains (Cd SexS1-x) embedded in glasses or suspended in colloidal solutions is proposed. The research will also focus on size dispersion, shape variations and polymeric coatings on the particles to enhance the optical nonlinearities. The project involves the theoretical formulation of the dynamic properties of quantum confined carriers in these grains and the calculation of the dielectric function. A generalized effective medium theory will be developed to obtain the overall dielectric response of the composite material which includes the metal or semiconductor grains and the dielectric host material. The generalized effective medium theory will be tested by numerical simulation of the composite medium. The resultant dielectric functions will be used to study the spatial propagation of electromagnetic waves in the medium. Our description will include transverse modes and forward- and backward-wave propagation to obtain realistic analysis of the materials. The investigators will study absorption and reflection of the electromagnetic waves, as well as, multiwave mixing. Experimental data on these materials will be analyzed in terms of these dielectric functions. The phenomena of optical bistability and optical phase conjugation will also be investigated in the composite materials. This project is expected to lead to a realistic assessment of the application of these materials for nonlinear optical devices.