Novel Colloidal Routes to Photonic Band Gap Materials

本研究计画将开发可图案化的三维光子带隙材料。 这样的系统将从不同的化学，功能和大小的耗尽稳定的二氧化硅悬浮液外延组装的硬球胶体晶体的模板。 通过接枝到二氧化硅颗粒表面或周围水性基质上的官能团的光聚合，组装体将被图案化以嵌入关键特征（例如，波导）。 通过用高折射率材料填充生长的胶体晶体，然后去除胶体模板，将产生具有所需光学对比度的PBG结构的形成。 最后，这些新型光子带隙材料的光子特性将通过实验测量，并与理论预测的行为进行比较。 工程可图案化的3-D PBG结构需要跨学科的努力，汇集了胶体科学，材料合成，PBG制造和光子特性领域的研究人员。 作为PBG结构模板的硬球胶体晶体将由不同功能的裸露、不带电的二氧化硅球的耗尽稳定悬浮液组装而成。 胶态外延将实现所需的面心立方晶体结构。然后，通过共聚焦光刻诱导的光聚合过程，将组装体原位凝胶化。 图案化的组件将用稀土掺杂的硫族化物玻璃渗透。 所得到的逆面心立方结构的光子学特性的特征在于相对于它们的光子带隙结构，波导性质，和发光。这一多学科研究项目的成功实施将导致在几个关键领域的新的科学认识。 耗尽增强胶体结晶的基础知识，胶体组件的机械和流变性能，以及胶体晶体的图案化，干燥和渗透行为的重要发现，以及它们的光子特性是预期的。 这些结果应该有广泛的影响，陶瓷的胶体加工，多孔材料的相关应用，包括催化剂，膜和生物结构的制造，并在技术上的重要领域的光子带隙材料所需的下一代信息技术。

This research project will develop patternable, 3-D photonic band gap (PBG) materials. Such systems will be templated from hard-sphere colloidal crystals assembled epitaxially from depletion-stabilized silica suspensions of varying chemistry, functionality, and size. Through photopolymerization of functional groups grafted onto the silica particle surfaces or of the surrounding aqueous matrix, the assemblies will be patterned to embed critical features (e.g., waveguides) needed for device applications. Formation of PBG structures with the desired optical contrast will be created by infilling as-grown colloidal crystals with a high refractive index material followed by removal of the colloidal template. Finally, the photonic properties of these novel PBG materials will be measured experimentally and compared to theoretically predicted behavior. Engineering patternable 3-D PBG structures requires an interdisciplinary effort that brings together researchers in the fields of colloid science, materials synthesis, PBG fabrication, and photonic properties. Hard-sphere colloidal crystals that serve as templates for PBG structures will be assembled from depletion-stabilized suspensions of bare, uncharged silica spheres of varying functionality. Colloidal epitaxy will be implemented to achieve the desired fcc crystal structure. The assemblies will then be gelled in situ by a photopolymerization process induced via confocal lithography. The patterned assemblies will be infitrated with rare earth doped chalcogenide glasses. The photonic properties of the resulting inverse fcc structures will be characterized with respect to their PBG structure, wave guiding nature, and luminescence. Successful implementation of this multidisciplinary research project will lead to new scientific understanding in several key areas. Fundamental knowledge of depletion-enhanced colloidal crystallization, the mechanical and rheological properties of colloidal assemblies, and important discoveries in the patterning, drying, and infiltration behavior of colloidal crystals, and their photonic properties are expected. These results should have broad impact on colloidal processing of ceramics, fabrication of porous materials for related applications including catalysts, membranes and biostructures, and on the technologically significant area of photonic band gap materials needed for the next generation of information technology.