Terahertz near-field spectroscopy of filled subwavelength sized apertures in thin metal films

Journal article (2013)
Department
IST/Imaging Science and Technology (AS) (TU Delft)
Copyright: © 2013 Optical Society of America
DOI: https://doi.org/doi:10.1364/OE.21.001101
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Published Date

10-01-2013

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Source:

Optics Express, 21 (1), 2013

ISSN:

1094-4087

Source:

http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-1-1101

Faculty

Applied Sciences

Department

IST/Imaging Science and Technology

Abstract

We have measured terahertz near-field spectra of cesium iodide crystals as small as ?10 ?m in diameter, which were deposited on single, sub-wavelength-sized apertures created in thin gold films on a substrate. The advantage of using small apertures for terahertz microspectroscopy is that only terahertz light that has interacted with the cesium iodide is observed. We find that around the transverse optical phonon frequency of cesium iodide, the amplitude transmission is as much influenced by the refractive index as by the absorption. We show that the ability to measure in the near-field of the apertures, where signals are relatively strong, allows us to measure on sample volumes as small as ?5×10?16 m3.

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