Plasmonic transmission lines:: from micro to nano scale with λ/4 impedance matching

The downscaling of conventional RF transmission lines methodologies to subwavelength plasmonic circuits is discussed and demonstrated for a lambda/4 transformer impedance matching. The nano- size transformer, matching between 0.5 mu m and 50nm wide plasmonic transmission lines, enhances the coupling efficiency by more than 285% compared to the direct (end fire) coupling - i. e. harvesting more than 86% of total incident power. The influence of the transverse resonances induced by the metal claddings of the input transmission line on the light harvesting is discussed as well. (C) 2007 Optical Society of America.