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Engineering perfect absorption in all-dielectric photoconductive metasurfaces (Conference Presentation)
Author(s): Oleg Mitrofanov; Thomas Siday; Polina Vabishchevich; Lucy Hale; Thomas Harris; Ting Shan Luk; John Reno; Igal Brener

Paper Abstract

Perfect absorption is desired in many photonic devices, in particular in optoelectronic switches, where the ability to change electrical conductivity with photoexcitation enables fast detectors and modulators. A metallic layer is typically introduced underneath the absorbing layer to realize perfect absorption, however this approach is often impractical for photoconductive devices. Here, we demonstrate perfect absorption using an all-dielectric metasurface consisting of a network of electrically connected nanoscale GaAs resonators. We develop a metasurface structure supporting two critically-coupled and degenerate magnetic dipole modes, with their effective magnetic dipole vectors in and out of the metasurface plane. Since the latter mode is symmetry-protected for incident waves at normal incidence, we break the resonator symmetry to enable excitation of the two modes simultaneously. We provide a physical model for the metasurface design and support it with detailed numerical simulations and experimental verification. We show that this metasurface can be switched between conductive and resistive states with extremely high contrast using an unprecedentedly low level of optical excitation. Funding statement: Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA-0003525.

Paper Details

Date Published: 9 September 2019
PDF
Proc. SPIE 11080, Metamaterials, Metadevices, and Metasystems 2019, 110802Q (9 September 2019); doi: 10.1117/12.2529419
Show Author Affiliations
Oleg Mitrofanov, Univ. College London (United Kingdom)
Thomas Siday, Univ. College London (United Kingdom)
Polina Vabishchevich, Sandia National Labs. (United States)
Lucy Hale, Univ. College London (United Kingdom)
Thomas Harris, Sandia National Labs. (United States)
Ting Shan Luk, Sandia National Labs. (United States)
John Reno, Sandia National Labs. (United States)
Igal Brener, Sandia National Labs. (United States)

Published in SPIE Proceedings Vol. 11080: