CAREER: Symmetry Control in Photonic Nanostructures for Enhanced Optical Properties

University Of New Mexico, Albuquerque NM

Investigators

Abstract

Non-technical Description: Photonic crystals are periodically structured artificial materials constructed from building blocks that are approximately a thousand times larger than those in atomic crystals. As symmetry in atomic crystals affects the electronic properties, symmetry in photonic crystals is a crucial factor determining the optical properties. However, because the repeating unit of photonic crystals is much larger than the periodicity in the atomic crystals, the symmetry in photonic crystals can be controlled by manipulating the structure of their repeating unit by using nanofabrication techniques. The research component of this CAREER award is to perform experimental and theoretical investigations of the symmetry effect on the optical properties of photonic crystals, aiming to achieve high performance of optical materials and optoelectronic devices. The research is integrated with nanoscience education activities at local K-12 schools and a nearby Native American community in collaboration with elementary school teachers. Technical Description: The main objective of the research project is to establish a concrete understanding of how the optical performance of photonic nanostructures is affected by the structure symmetry. For efficient control of point group symmetry, a fabrication technique recently developed by the principal investigator is employed. The technique involves wet etching processing of silicon wafers. Translational symmetry is broken in a controlled manner by methods based on colloidal self-assembly. The symmetry effect on optical properties is investigated for: (i) high efficiency in thin-film organic solar cells, targeting light absorption that surpasses the conventional theoretical limit; (ii) high photoresponsivity in Si-based hot-electron infrared detectors, targeting broader band photoresponsivity than current benchmarks; and (iii) artificial white coatings mimicking nanostructures in white beetle scales, targeting thinner scales with stronger light scattering among low-refractive-index materials. Methods based on colloidal self-assembly are developed to fabricate such structures with precise control over structural parameters to determine the relationship between the structure and the optical scattering properties.