Silver-Coated Teflon Tubes for Waveguiding at 1–2 THz

Abstract

Realization of single-mode low-loss waveguides for 1.0-2.0 THz remains a challenging problem due to large absorption in most dielectrics and ohmic losses in metals. To address this problem, we investigate dielectric-lined hollow metallic waveguides fabricated by coating 1-mm diameter 38-μm-thick polytetrafluoroethylene tubes with silver. These waveguides support a hybrid HE 11 mode, which exhibits low attenuation and low dispersion. Quasisingle-mode propagation is achieved in the band of 1.0-1.6 THz, in which the hybrid HE 11 mode is supported by the waveguide. In this band, the experimentally measured loss is 20 dB/m (~0.046 cm −1 ), whereas the numerically computed loss is~7 dB/m (~0.016 cm). The difference is attributed to additional losses in the dielectric layer, which can be reduced by using alternative polymers.

Generation of radially-polarized terahertz pulses for coupling into coaxial waveguides

“…To assist in the discussion, the numerically-computed modal group delay for the first two waveguide modes (the fundamental TEM and the first higher-order TE 11 modes13) along with the first higher-order mode with longitudinal polarization field component (TM 01 mode1) are superimposed in the spectrograms; the eigenmode analysis follows the same methodology as in ref. 30 (see also Methods). Almost flat dispersion of spectral components at up to 1.5 THz is observed at t  = 8 ps, the moment that corresponds to the leading THz pulse in Fig.…”

Beam Profiling of a Commercial Lens-Assisted Terahertz Time Domain Spectrometer

“…Spatially sampling the THz beam by raster scanning a pinhole in the xy-plane across the setup is the most popular method for both far-field [19] and near-field [25]- [27] beam mapping. Precautions should be taken for far-field mapping, however, as discussed in the next subsection.…”

Fiber-Drawn Metamaterial for THz Waveguiding and Imaging

“…Several waveguide solutions based on technologies from both electronics and photonics have been proposed [38][39][40][41][42]; among these hollow core waveguides are one of the best options for guiding THz radiation due to the very low material absorption of air. However, hollow core waveguides suffer from multimode operation as they have a core diameter larger than the operating wavelength to minimize reflection losses [43][44][45][46][47]. Metamaterials offer a new paradigm to reduce the number of modes due to their unusual optical properties [48,49].…”