Near-field phenomena observed with terahertz pulses

K. Wynne, J. Carey, J. Zawadzka, D.A. Jaroszynski

Research output: Contribution to conferencePaperpeer-review


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.
Original languageEnglish
Number of pages8
Publication statusPublished - Jun 1999
EventTerahertz spectroscopy and applications 11 - Munich, Germany
Duration: 14 Jun 1999 → …


ConferenceTerahertz spectroscopy and applications 11
CityMunich, Germany
Period14/06/99 → …


  • ultrafast
  • imaging
  • wave propagation
  • terahertz
  • tunneling


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