Tapered dual elliptical plasmon waveguides as highly efficient terahertz connectors between approximate plate waveguides and two-wire waveguides

We present a tapered dual elliptical plasmon waveguide for terahertz waves. This element is composed of a pair of tapered elliptical metal structures and is especially suitable for the coupling of terahertz waves from an approximate plate waveguide to a two-wire waveguide. The long axes of the two ellipses gradually reduce to the same sizes as the short axes, and thus the two-ellipse structure is now a two-wire waveguide. The slowly tapered structure eliminates the reflection and scattering during the coupling process according to WKB approximation. The numerical result shows that the coupling efficiency of this connector can reach as high as 94%. (C) 2014 Optical Society of America