Partial Order Colloidal Phases as Photonic Solids

作为光子固体的偏序胶体相

• 批准号: 1508592
• 负责人: Chekesha Watson
• 金额: $ 37.73万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1508592&HistoricalAwards=false
• 关键词: Partial; Order; Colloidal; Phases; Photonic

Nontechnical Description: The objective of this research project is to fabricate partial order photonic mesophases made of non-spherical colloidal particles and characterize their optical properties. These novel materials exhibit structural ordering between those of crystals and glasses and hold promise to strongly modify spectral and angular transport of light (similar to crystals) and also to promote bandgaps with high isotropy (similar to glasses). The research helps clarify the mechanisms for the formation of photonic band gaps in various photonic media and seeks novel optical properties such as negative refraction for ultrahigh resolution lenses and low speed of light for enhanced nonlinear optics. The education activities of this project include developing informal science learning activities at the Ithaca Sciencenter; broadening participation of underrepresented minorities and women in science through involving them in research; and contributing to a manual of the best practices for undergraduate research developed by the Institute for Broadening Participation. In particular, graduate student facilitators are trained in science communication to public audiences including children.Technical Description: This project exploits the thermodynamics of shape-anisotropic colloids to capture photonic mesophases, a new class of photonic materials in which order and disorder cohabit, and to study their photonic properties. The research aims to develop an understanding of the types and bounds of order that promote significant photonic properties (i.e., photonic band gaps, negative refraction, slow light) and an ability of fabricating photonic mesophase materials for photonic slabs via low-cost, large-area self-assembly. Specifically, the self-organization of anisotropic colloids and shape-binary mixtures is mapped out under wedge-cell confinement to elucidate the conditions for stabilizing photonic mesophases. Confinement height up to five layers, system density and interparticle interactions are varied and the self-organization is studied using quantitative confocal microscopy imaging with precise spatial and temporal resolution. The spatial distributions of the mode fields, transmission (reflection) spectra and density of states are calculated to elucidate the structure and optical property correlations. The photonic mesophases are characterized using angle-resolved specular reflectance measurements to probe the dispersion relations. The effects of partial order on refraction and slow-light propagation properties are determined from the analysis of equifrequency contours and the calculation of the group velocity at the band gap edges, respectively. Simulations of the refraction and the flat lens imaging of a point source are performed for photonic mesophases that exhibit all-angle negative refraction and effective refractive index of negative one.

非技术描述：本研究项目的目标是制备由非球形胶体粒子组成的偏序光子介相，并表征其光学性质。这些新型材料表现出晶体和玻璃之间的结构有序性，有望强烈地改变光的光谱和角度传输(类似于晶体)，并促进具有高各向同性(类似于玻璃)的带隙。这项研究有助于阐明各种光子介质中光子带隙的形成机制，并寻求新的光学性质，如用于超高分辨率透镜的负折射和用于增强非线性光学的低速光速。该项目的教育活动包括在伊萨卡科学中心开展非正式的科学学习活动；通过让代表不足的少数群体和妇女参与研究，扩大他们对科学的参与；以及为研究所编写的本科生研究最佳做法手册作贡献，以扩大参与。特别是，研究生辅导员接受了面向包括儿童在内的公众的科学交流方面的培训。技术描述：该项目利用形状各向异性胶体的热力学来捕捉光子介相，这是一种有序和无序共存的新型光子材料，并研究它们的光子性质。这项研究的目的是了解促进光子特性(即光子带隙、负折射、慢光)的有序的类型和界限，以及通过低成本、大面积自组装来制备用于光子平板的光子中间相材料的能力。具体地说，绘制了楔形格子约束下各向异性胶体和形状二元混合物的自组织图，阐明了稳定光子介相的条件。限制层高达五层，系统密度和粒子间相互作用是不同的，并利用具有精确空间和时间分辨率的定量共焦显微镜成像研究了自组织。计算了模场、透射(反射)谱和态密度的空间分布，阐明了结构和光学性质之间的关联。利用角度分辨镜面反射测量对光子介相进行了表征，以探测色散关系。通过对等频轮廓的分析和带隙边缘群速度的计算，确定了偏序对折射率和慢光传输特性的影响。对全角度负折射率和有效折射率为负的光子介相，对点源的折射和平面透镜成像进行了模拟。