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Summary: Sub-wavelength plasmonic modes in a
conductor-gap-dielectric system with a nanoscale
gap
Ivan Avrutsky1,*
, Richard Soref2
and Walter Buchwald2
1
Department of Electrical and Computer Engineering, Wayne State University, Detroit, MI 48202, USA
2
Sensors Directorate, Air Force Research Laboratory, AFRL/RYHC, Hanscom Air Force Base,
Massachusetts 01731-2909, USA
*ivan.avrutsky@wayne.edu
Abstract: We study guided modes in a conductor-gap-dielectric (CGD)
system that includes a low-index dielectric gap layer of deep sub-
wavelength thickness sandwiched between a conductor and a high-index
dielectric cladding. Analysis of the dispersion equation for CGD modes
provides an analytical estimation for the cut-off thickness of the gap layer.
This guided mode is unusual because it exists when the gap thickness is less
than the cutoff thickness. In the direction normal to the interfaces, the modal
electric field is tightly confined within the gap. Sub-wavelength lateral
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