Vertical coupling of long-range surface plasmon polaritons

(W)e evaluated and demonstrated strong vertical-coupling characteristics of vertical directional couplers based on long-range surface plasmon polaritons (LRSPPs) at 1.55 mu m wavelength. Fundamental even and odd modes supported by LRSPP metal-stripe waveguides compete more strongly on vertical coupling structures than on lateral coupling structures, possibly leading to less power consumption for switching and to compactness in device length and width. LRSPP-based vertically coupled routing of signals can also be a powerful means of developing three-dimensional photonic integrated circuits and optical printed circuit boards. (c) 2006 American Institute of Physics.