This paper reports an experimental and simulation study of a tapered parallel-plate waveguide (TPPWG) to improve THz coupling to the plate separation gap. The flat- and round-type TPPWG without any silicon lens is compared to the parallel-plate waveguide (PPWG) with a plano-cylindrical silicon lens. The spectrum amplitudes of the input-side TPPWG and the input- and output-side TPPWG both having a 3 degrees slop angle increased about 56% and 103% at 1 THz when compared to that of the PPWG. Since the input- and output-side TPPWG had almost no impedance mismatch to the propagating THz wave, coupling to the waveguide could be improved twice compared with the PPWG.

Articles you may be interested inMinimization of reflection at the boundaries of a finite-size coupled terahertz cavity in a metal air-gap waveguide Properties of defected one-dimensional terahertz plasmonic crystal films in a metal air-gap waveguide J. Appl. Phys. 110, 093101 (2011); 10.1063/1.3658255Photonic band anti-crossing in a coupled system of a teraherz plasmonic crystal film and a metal air-gap waveguideWe present numerical and experimental demonstration of slowing down the speed of terahertz guiding modes of a metal air-gap waveguide by using a one-dimensional coupled plasmonic cavity. The speed of terahertz guiding modes gets slower as a distance between metal plates of the waveguide decreases because the coupling strength between cavities gets weaker as the distance decreases. The coupled plasmonic cavities in a metal air-gap waveguide could be useful in enhancing the interaction between the guiding modes and matters and manipulating terahertz waves in a time domain. V C 2012 American Institute of Physics. [http://dx.

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