Metallic slit waveguide for dispersion-free low-loss terahertz signal transmission

Transmission characteristics of a metallic waveguide are presented combining negligible dispersion, very low attenuation, and two-dimensional mode confinement. The waveguide is fabricated by sawing a 270 mu m wide slit through a 40 mm wide and 300 mu m thick silicon slab and subsequent metalization of all faces. Single-mode terahertz pulses propagating through the slit are excited at one end of the waveguide using a photoconductive antenna array and detected with a freely positionable photoconductive probe tip. Low-loss propagation with negligible group velocity dispersion is observed in the 0.1-1.0 THz frequency range. Compared to former approaches considerably stronger mode confinement is achieved.