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Proceedings Paper

Beaming and filtering at terahertz frequencies in liquid crystal filled metallic grating
Author(s): Daniele Lo Forti; Domenico de Ceglia; Maria A. Vincenti; Michael Scalora; Robert G. Lindquist
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Paper Abstract

The increasing interest in the terahertz frequency range is motivated by the unique property of sub-millimeter waves to penetrate any nonmetallic materials such as fabric and plastic, and sense objects distinctive signatures. Furthermore, because of its low photon energy, terahertz radiation can be used in medical applications for accurate imaging without damaging tissues. For these reasons there is a growing need of devices dedicated to control the radiation in this frequency range. Current established technology uses non-tunable, mesh-like filters and mechanical mirrors to filter and manipulate THz radiation. We study electrically-controlled beaming and filtering abilities of sub-wavelength metallic gratings. The geometry consists of a finite array of slits in a metallic film separated by spacers and filled with liquid crystal (LC). We exploit the Fabry-Perot (FP) like resonances of the slits to filter THz radiation. We then simulate the application of an external voltage across the metallic grating in order to generate an electro-optic torque force on the LC molecules and change the dielectric constant inside the slits. This results in a large tuning effect on the FP resonances. We also predict that a linear voltage distribution across the grating induces a linear phase delay resulting in a beamsteering action for radiation incoming at grazing incidence.

Paper Details

Date Published: 12 September 2013
PDF: 7 pages
Proc. SPIE 8828, Liquid Crystals XVII, 88281E (12 September 2013); doi: 10.1117/12.2025512
Show Author Affiliations
Daniele Lo Forti, Univ. of Alabama, Huntsville (United States)
Domenico de Ceglia, National Research Council, U.S. Army ARMDEC (United States)
Maria A. Vincenti, National Research Council, U.S. Army ARMDEC (United States)
Michael Scalora, U.S. Army ARMDEC RDECOM (United States)
Robert G. Lindquist, Univ. of Alabama in Huntsville (United States)

Published in SPIE Proceedings Vol. 8828:
Liquid Crystals XVII
Iam Choon Khoo, Editor(s)

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