Atypical Photonic Slabs by Quasi-2D Colloidal Self-Assembly

技术：该项目将解决引入光子板排列复杂性的挑战。整个准二维平板厚度的垂直变化将通过约束下的胶体处理引入。二维和三维之间的冻结可以在与薄颗粒膜整体层间距不相称的间隙区域实现结构转变。从共聚焦显微镜的荧光壳修饰粒子在楔形细胞几何，真实的空间相组织将被研究作为一个函数的粒子形态，系统密度和细胞高度。形状各向异性胶体的合成将用于制备非常规有序固体的构建块以及在施加的包装约束下的晶体。通过实验和局限态的蒙特卡罗模拟确定的顺序参数和相关函数的定量评估将为模拟模型提供信息，以评估板状图案及其各种逆实施例的光学特性，例如，残余体积、壳和骨架逆结构。溶胶-凝胶和纳米颗粒前驱体的溶液处理以及气相沉积将应用于回填和共组装路线反演，以获得高折射率对比度。该项目将加强对减少对称性、扩展维数和新型偏序结构如何影响光子晶体板中光-物质相互作用的理解。为此，将计算光子带结构，并探讨结构参数（如位置顺序、方向顺序、基序形态、基复杂度、介电填充分数、折射率对比）对互易空间中高对称性点光子带行为的相对影响。模式场分布的互补分析将应用于合理的形成完整的二维光子带隙。一项应用于光子板结构的强大实验技术将用于确定禁带和带隙频率，光子态的修正密度，以及光子模式的实验场分布。也就是说，电子能量损失谱技术应用于扫描透射电子显微镜将实现高空间分辨率的光子表征。为了研究平板的折射特性，还将计算等频率等高线图，并模拟光在平面内通过非典型结构的传播，以确定左、右、正、负折射行为的频率和方向，作为结构参数变化的函数。将研究由自组装定义的适当指示构型的点源成像，以评估光子板材料在平面透镜应用中的分辨率。通过这个项目，将建立结构-属性-处理-性能的关系。非技术：该奖项将为传统黑人学院和大学以及女子学院的学生提供更多的本科研究机会。PI计划通过与康奈尔大学共享设施相关的REU项目，吸引这些机构的本科生进行研究。还将通过会议支助提出研究报告和举办专业发展讲习班来提供充实。将寻求与本地机构的研究人员建立持久的关系，包括访问学生继续合作，并可能为康奈尔大学的研究生项目提供额外的招聘机会。围绕分布式研究和“科学即艺术”的模式，计划一个非正式的公共教育项目，将材料研究的图像放置在公共图书馆展览中，以促进该领域的发展。此外，还组织由乌拉尔大学研究生主持的系列研讨会，邀请杰出的未被充分代表的少数民族（乌拉尔大学）教师进行研究讲座和专业发展。

Technical: This project will address the challenge of introducing complexity in photonic slab arrangements. Vertical variation throughout the thickness of quasi-2D slabs will be introduced via colloidal processing under confinement. Freezing between two and three dimensions accesses structural transitions in gap regions incommensurate with integral layer spacing of thin particulate films. From confocal microscopy of fluorescent-shell modified particles in wedge cell geometry, the real space phase organization will be investigated as a function of particle morphology, system density and cell height. The synthesis of shape anisotropic colloids will be performed to prepare building blocks for unconventionally ordered solids in addition to crystals under the imposed packing constraints. Quantitative evaluation of order parameters and correlation functions determined experimentally and from Monte Carlo simulations of the confined states will inform simulation models to evaluate the optical properties of the slab patterns and their various inverse embodiments¯ for example, residual volume-, shell-, and skeleton inverse structures. Sol-gel and nanoparticle precursors for solution processing as well as vapor phase depositions will be applied in backfilling and co-assembly routes to inversion to obtain high-refractive index contrast. The project will enhance the understanding of how reduced symmetry, expanded dimensionality, and novel classes of partial order structuring impact light-matter interactions in photonic crystal slabs. To this aim, photonic band structures will be calculated and the relative influence of structural parameters such as positional ordering, orientation ordering, motif morphology, basis complexity, dielectric filling fraction, refractive index contrast on the behavior of photonic bands at high symmetry points in reciprocal space will be explored. Complimentary analysis of mode field distributions will be applied to rationalize the formation of full 2D photonic band gaps. A powerful experimental technique in its infancy for application to photonic slab structures will be used to confirm stop band and band gap frequencies, modified density of photonic states, in addition to the experimental field distribution of photonic modes. Namely, the Electron Energy Loss Spectroscopy technique applied in a Scanning Transmission Electron Microscope will enable the photonic characterization at high spatial resolution. For investigation of refraction properties of the slabs, equal frequency contour plots will also be calculated and the light propagation in-plane through atypical structures will be simulated to determine frequency and directions for left-handed, right-handed, positive- and negative refraction behavior as a function of structural parameter variants. Point source imaging for appropriately indicated configurations defined by self-assembly will be studied to evaluate resolution in the flat lens application of the photonic slab materials. Through this project the structure-property-processing-performance relationships will be established. NonTechnical: This award will enhance undergraduate research opportunities for students in Historically Black Colleges and Universities as well as Women's Colleges. The PI plans to engage undergraduates to conduct research from these institutions through the REU programs associated with the Cornell Shared Facilities. Enrichment will also be offered through conference support for presenting research and for professional development workshops. Lasting relationships with researchers in the home institution will be sought for continued collaboration involving the visiting student and potentially providing additional recruiting opportunities to Cornell's graduate programs. An informal public education project is planned around a distributed research and "Science as Art" model to place images of materials research in public library exhibits which will promote the field. As well, the organization of seminar series hosted by URM graduate fellows to invite distinguished underrepresented minority (URM) faculty for research talks and professional development.