"Consequences of spatial antisymmetry on light"

Seminar by

Dr. Angelo Mascarenhas, NREL

Abstract: When light traverses an interface across which the permittivity, and permeability, change sign, it undergoes negative refraction and the medium with negative values of and must be interpreted as having a negative refractive index . In the past few years this has been experimentally demonstrated by several groups. We have analyzed light propagating in lattices comprised of 2-D tilings in which alternating tiles are made up of media with refractive index whose values alternate in sign acoss tile boundaries. Using both numerical ray tracing and wave equation expansion, I will show that when the tiling belongs to certain antisymmetric plane groups, every light ray is exactly bound into a closed, lossless path. The extension to antisymmetric 3-D space groups will also be discussed. The study provides unique insights into the consequences of spatial antisymmetry on light.

BIOGRAPHY: Dr. Angelo Mascarenhas is a Principal Scientist in the Center for Materials Sciences at NREL. He has been working at NREL in the area of spectroscopic research on photovoltaic materials for improved and advanced Solar Cells. He has been the Team leader for Solid State Spectroscopy for the past 16 years and is currently Research Principal Supervisor for the Experimental Materials Sciences Section at NREL and has done extensive research on the harnessing the material consequences of semiconductor alloy instabilities such as spontaneous ordering and spontaneous composition modulation for optoelectronic applications. His current research focuses on the phenomenon of spontaneous ordering and isoelectronic co-doping for tailoring the optical properties of semiconductor alloys, and its applications to very high efficiency solar cells, solid state lighting, and advanced communication lasers. He has over 230 research publications including over 70 in the Physical Review, is the editor of one book and two conference proceedings related to self-organized phenomena resulting from kinetic and thermodynamic instabilities in semiconductor alloys. He has authored several invited papers and book chapters as well as organized several symposia on these topics, and is a co-inventor on five patent applications related to advanced concepts for solar cells.