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Proceedings Paper

Grating-coupled surface plasmons on InSb: a versatile platform for terahertz plasmonic sensing (Conference Presentation)
Author(s): Diyar Talbayev; Jiangfeng Zhou; Shuai Lin; Khagendra Bhattarai

Paper Abstract

Detection and identification of molecular materials based on their THz frequency vibrational resonances remains an open technological challenge. The need for such technology is illustrated by its potential uses in explosives detection (e.g., RDX) or identification of large biomolecules based on their THz-frequency vibrational fingerprints. The prevailing approaches to THz sensing often rely on a form of waveguide spectroscopy, either utilizing geometric waveguides, such as metallic parallel plate, or plasmonic waveguides made of structured metallic surfaces with sub-wavelength corrugation. The sensitivity of waveguide-based sensing devices is derived from the long (1 cm or longer) propagation and interaction distance of the THz wave with the analyte. We have demonstrated that thin InSb layers with metallic gratings can support high quality factor “true” surface plasmon (SP) resonances that can be used for THz plasmonic sensing. We find two strong SP absorption resonances in normal-incidence transmission and investigate their dispersion relations, dependence on InSb thickness, and the spatial distribution of the electric field. The sensitivity of this approach relies on the frequency shift of the SP resonance when the dielectric function changes in the immediate vicinity of the sensor, in the region of deeply sub-wavelength thickness. Our computational modeling indicates that the sensor sensitivity can exceed 0.25 THz per refractive index unit. One of the SP resonances also exhibits a splitting when tuned in resonance with a vibrational mode of an analyte, which could lead to new sensing modalities for the detection of THz vibrational features of the analyte.

Paper Details

Date Published: 9 June 2017
PDF: 1 pages
Proc. SPIE 10210, Next-Generation Spectroscopic Technologies X, 102100X (9 June 2017); doi: 10.1117/12.2263717
Show Author Affiliations
Diyar Talbayev, Tulane Univ. (United States)
Jiangfeng Zhou, Univ. of South Florida (United States)
Shuai Lin, Tulane Univ. (United States)
Khagendra Bhattarai, Univ. of South Florida (United States)

Published in SPIE Proceedings Vol. 10210:
Next-Generation Spectroscopic Technologies X
Mark A. Druy; Richard A. Crocombe; Steven M. Barnett; Luisa T. Profeta, Editor(s)

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