Influence of the dielectric substrate on the terahertz electric near-field of a hole in a metal

Journal article (2009)
Department
Imaging Science and Technology (AS) (TU Delft)
Copyright: © 2009 Optical Society of America
DOI: https://doi.org/doi:10.1364/OE.17.017412
Apertures Subwavelength structures Terahertz imaging
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Published Date

15-09-2009

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Source:

Optics Express, 17 (20), 2009

ISSN:

1094-4087

Source:

http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-20-17412

Faculty

Applied Sciences

Department

Imaging Science and Technology

Abstract

We have studied theoretically and experimentally the influence of a dielectric substrate on the frequency-dependent terahertz electric near-field of a small hole in a metal layer. We find that the near-field transmission spectrum and the two-dimensional field distribution of an empty hole in a thin metal layer on a substrate are almost identical to that of a hole which is also filled with the same dielectric material as the substrate. For thicker metal layers, however, the near-field spectra of filled and unfilled holes become very different. In addition, for thick metal layers, the two-dimensional field distributions are more strongly affected by the substrate, especially if we allow for an air gap between the metal and the substrate. Our results validate the -somewhat unusual- two-dimensional field distribution measured beneath a hole in a thick metal foil and highlight the effect that a substrate can have on the measurement of the near-field of an object.

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