Terahertz surface wave propagation and focusing on conical metal wires

A theory for treating terahertz (THz) surface wave propagation and focusing on conical metal wire waveguides is presented. According to the theory, the surface wave propagation and focusing on the conical copper wire waveguide is investigated by the numerical calculation, and the results show the theory agrees with experimental measurement result obtained by Ji et al. The theory presented provides a basis for describing surface wave propagation and focusing on conical metal wire waveguides and, importantly, the theory suggests that a simple conical metal wire can be used for subwavelength energy concentration and superfocusing. (C) 2008 Optical Society of America