Low-Loss, Impedance-Matched Dirac-Cone Metamaterials for Integrated Optics

非技术描述：本项目实现了一种新型光学材料——零折射率集成阻抗匹配超材料。这些材料不会像普通的透明材料那样弯曲光线，并且可以集成到光学器件中。利用这一新颖的材料平台，本项目探索了零折射率材料的奇异物理特性，并在集成光子学中实现了许多应用，包括光束导向和超耦合。为了有效地将这种新型光学超材料从学术界转移到商业应用中，研究团队与工业伙伴密切合作。这个项目在两个方面为首席研究人员的教育和推广工作做出了贡献：首先，这种新型的超材料可以作为一个简单的教育和展览平台，展示超材料的奇异材料特性和有趣的物理现象；其次，参与该项目的不同层次的学生获得了最先进研究的研究经验。技术描述：本项目研究由光子晶体布里渊带中心的狄拉克锥获得的光学超材料。由于在伽玛点附近满足均匀化准则，光子晶体在狄拉克点附近可以看作是具有低折射率或零折射率的均匀体超材料。这种方法有三个重要的优点：低损耗、自由空间阻抗匹配和各向同性。该项目的目标是设计、制造和表征由二维方形硅柱阵列组成的狄拉克锥超材料，该材料可以使用标准的平面工艺制造，然后，基于该二维平台，从理论上和实验上展示几种奇异的物理现象和潜在的应用，包括光束导向和超耦合。具体而言，研究方法是：1)利用分析模型和商用模拟器进行理论设计；2)利用哈佛纳米系统中心的洁净室设施进行实验制备；3)利用光纤-发射耦合系统对狄拉克-锥超材料光学特性的实验测量。

Non-technical Description: This project implements a new form of optical materials - integrated impedance-matched metamaterials with zero refractive index. These materials do not bend light like ordinary transparent materials and can be incorporated in optical devices. Using this novel material platform, this project explores the exotic physics of zero refractive index materials and implements a number of applications in integrated photonics, including beam-steering and super-coupling. To efficiently transfer this new type of optical metamaterial from academia to commercial applications, the research team collaborates closely with industrial partners. This project contributes to the Principal Investigators' effort in education and outreach in two ways: first, this novel type of metamaterial can be used as a simple platform in education and exhibitions to demonstrate the exotic material properties and interesting physical phenomena of metamaterials; second, students at many different levels involved in this project gain research experience in state-of-the-art research.Technical Description: This project investigates optical metamaterials achieved by a Dirac cone at the center of the Brillouin zone of a photonic crystal. Because the homogenization criterion is met in the vicinity of the Gamma point, the photonic crystal can be treated as a homogeneous bulk metamaterial with low or zero refractive indices near the Dirac point. This approach offers three important advantages: low loss, free-space impedance matching, and isotropy. The goal of this project is to design, fabricate, and characterize Dirac-cone metamaterials consisting of 2D square array of silicon pillars, which can be fabricated using standard planar processes, then, based on this 2D platform, to theoretically and experimentally demonstrate several exotic physical phenomena and potential applications including beam-steering and super-coupling. Specifically, the research approaches are: 1) theoretical design using analytical models and commercially available simulators; 2) experimental fabrication using the clean room facilities at the Harvard Center for Nanoscale Systems; 3) experimental measurements of optical properties of Dirac-cone metamaterials using a fiber-launch coupling system.