Propagation Loss Optimization in Metal/Dielectric Coated Hollow Flexible Terahertz Waveguides

Low-loss hollow flexible metal/dielectric coated polycarbonate waveguides have been designed and fabricated for the maximal transmission of Terahertz radiation (THz). Attenuation characteristics of Terahertz radiation in Ag/Au coated waveguides with bore diameters 4.1 mm, 3.2 mm, 2 mm were studied at 215 μm wavelength and the maximal transmission was obtained by coupling the lowest loss TE11 mode from an optically pumped terahertz laser. Transmission loss can be reduced substantially by adding a dielectric layer to the metal coated waveguide and by coupling HE11 mode into it. Polystyrene (PS) was chosen to be the dielectric, due to its low extinction coefficient, which enhances the transmission through the waveguide. A propagation loss of less than 1 dB/m was achieved with these metal/dielectric coated waveguides.