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Proceedings Paper

Near-field phenomena observed with terahertz pulses
Author(s): Klaas Wynne; John Carey; Justyna Zawadzka; Dino A. Jaroszynski
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Paper Abstract

Propagation of free-space femtosecond THz pulses (T rays) through and past metal structures with dimension on the order of a wavelength has been studied. In waveguides with diameters close to one wavelength, it is found that the phase velocity can become superluminal and even infinite or negative. T rays that propagate past a 100-micrometers metal wire are delayed when the polarization is perpendicular and advanced when it is parallel. In this case, it is also observed that the centroid velocity can become superluminal. Many of the result do not conform to simple waveguide theory, because of multiple reflections of the evanescent waves inside the waveguide. This 'Fabry-Perot' effect for evanescent waves is the cause of the negative phase velocities below the waveguide cutoff.

Paper Details

Date Published: 9 September 1999
PDF: 9 pages
Proc. SPIE 3828, Terahertz Spectroscopy and Applications II, (9 September 1999); doi: 10.1117/12.361042
Show Author Affiliations
Klaas Wynne, Univ. of Strathclyde (United Kingdom)
John Carey, Univ. of Strathclyde (United Kingdom)
Justyna Zawadzka, Univ. of Strathclyde (United Kingdom)
Dino A. Jaroszynski, Univ. of Strathclyde (United Kingdom)


Published in SPIE Proceedings Vol. 3828:
Terahertz Spectroscopy and Applications II
J. Martyn Chamberlain, Editor(s)

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