Novel Colloidal Routes to Photonic Band Gap Materials

该研究项目将开发可形成图案的三维光子带隙(PBG)材料。这样的系统将以硬球胶体晶体为模板，从不同化学、功能和大小的耗尽稳定的二氧化硅悬浮液外延组装而成。通过接枝到二氧化硅颗粒表面或周围水基质上的官能团的光聚合，组装组件将被图案化，以嵌入设备应用所需的关键特征(例如，波导)。通过在生长的胶体晶体中填充高折射率材料，然后去除胶体模板，将形成具有所需光学对比度的PBG结构。最后，对这些新型光子带隙材料的光子特性进行了实验测量，并与理论预测的行为进行了比较。设计可形成图案的3-D PBG结构需要跨学科的努力，将胶体科学、材料合成、PBG制造和光子特性等领域的研究人员聚集在一起。用作PBG结构模板的硬球胶体晶体将由不同功能的裸露、不带电荷的二氧化硅球的耗尽稳定悬浮液组装而成。胶体外延将实现所需的面心立方晶体结构。然后，这些组件将通过共聚焦光刻诱导的光聚合过程进行原位凝胶。图案化的组件将使用稀土掺杂的硫化物玻璃。所得到的逆面心立方结构的光子特性将根据它们的PBG结构、波导性和发光来表征。这一多学科研究项目的成功实施将导致对几个关键领域的新的科学理解。课程内容包括耗竭增强型胶体结晶的基础知识、胶体组件的力学和流变性，以及在胶体晶体的图案化、干燥和渗透行为及其光子特性方面的重要发现。这些结果应该会对陶瓷的胶体加工、相关应用的多孔材料的制造(包括催化剂、膜和生物结构)以及下一代信息技术所需的光子带隙材料的重大技术领域产生广泛影响。

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.