Guidance properties on the surface of copper and stainless steel wires in terahertz frequency range

We report an experimental and theoretical study of the guidance properties on the surface of copper and stainless steel wires in the terahertz frequency range. Instead of using quasioptic coupling, optoelectronically generated THz pulses by silicon on sapphire (SOS) photoconductive dipole antenna were directly launched onto a 0.5-mm-diameter copper and stainless steel wire. After a 71-cm propagation of the curved wires, the guided THz pulses were directly detected at the end of the wires using another SOS photoconductive dipole antenna. The guided THz pulses for the two wires have very high attenuation and group velocity dispersion. Because of the stainless steel wire´s minimal conductivity, it has better guidance property compared with that of copper wire. We suggest the use of the copper wire for the straight region and stainless steel wire for the curved region to ensure minimal THz attenuation.