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

Harvard University, Cambridge MA

Investigators

Abstract

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.