Designer reflectors using spoof surface plasmons in the terahertz range.

We show that spoof surface plasmons can be used to control the reflection of terahertz radiation at the output facet of a parallel-plate waveguide. Using a periodic groove pattern on the output face, reflectivity approaching 100% can be achieved within a limited spectral range. Unlike the conventional geometry for plasmon-enhanced transmission, this approach enables a unique method for studying the coupling between the guided mode and the surface plasmon through angle-dependent measurement of the plasmon-mediated reflection. A simple model incorporating the surface plasmon coupling to the waveguide mode can adequately explain all of the observed phenomena, including the observed Goos-Hanchen shift in the reflected beam. [ABSTRACT FROM AUTHOR]