Time-Modulated Optical Gradient Metasurfaces
Abstract
Time-Modulated Optical Gradient Metasurfaces Principal Investigator: Andrea Alù Department of Electrical and Computer Engineering, The University of Texas at Austin Metasurfaces characterized by a transverse spatial gradient of local impedance have recently opened exciting directions for light manipulation at the subwavelength scale, enabling an unprecedented degree of wavefront engineering and manipulation, including manipulation of the propagation direction, polarization state, orbital angular momentum, and more. Yet, there are fundamental constraints that gradient metasurfaces have to comply with, mostly determined by inherent symmetries, which limit their overall efficiency and level of applicability. During this effort, we will significantly extend the concept of gradient metasurfaces enriching it with transverse temporal gradients, which will enable breaking the mentioned constraints and dramatically enhance the possibilities and practical applicability for light manipulation offered by ultrathin engineered surfaces. This effort constitutes a fundamental basic research program aimed at conceiving, designing, optimizing and experimentally realizing time-modulated gradient metasurfaces, able to control and tailor radiation, thermal emission, transmission, reflection and polarization, in ways not available with conventional static technology. We will prove that spatio-temporal variations over a surface may realize unusual non-reciprocal electromagnetically induced transparency responses, opening a narrow window of one-way transmission in an otherwise opaque surface. We will also prove the possibility of realizing non-reciprocal radiation and thermal emission from a surface, of interest for infrared applications, energy harvesting and thermal management, as well as for communications, and we will exploit time-modulation to realize a new form of parity-time symmetric metamaterials. Finally, we will explore the exciting possibilities offered by opto-mechanics to enable nonreciprocity and parity-time symmetry, opening new directions in nano-optics. The ultimate objective of this project is to conceptually, numerically and experimentally realize novel, ultrathin optical devices based on time-modulated metasurfaces that can provide a new degree of control of the incoming wavefront, and of radiation and emission. During the course of this project, we will explore various approaches compatible with our goal of introducing time-varying elements in complex metasurface geometries, including timemodulated varactors and electro-optic effects, nonlinearities, and opto-mechanical systems. These explorations will extend the impact of the proposed concepts beyond light and infrared wavelengths, also to include radio-waves, mechanical waves and sound. The proposed efforts will have a clear impact in several areas of interest for the Department of Navy, including communications, orientation, signaling, sensing, and thermal management. Within this three-year effort, we will not only spend substantial efforts in fundamental research on novel metasurface technology, developing a rigorous theoretical framework, full-wave analysis and design of ultrathin time-varying optical devices, but we will also spend experimental efforts on their proof-of-concept realization and characterization. Our investigations will significantly advance the general field of metamaterials and metasurfaces, and train a new generation of students on exciting and inherently interdisciplinary research topics at the frontier of optics and electromagnetics research. Total funds requested from ONR (over a 3-year period): $500,311
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 12, 2016
- Source ID
- N000141512685
Entities
People
- Andrea Alù
Organizations
- Office of Naval Research
- United States Navy
- University of Texas at Austin