Three-dimensional Gap Plasmon coupler

In this paper, we have investigated the performance of a nano-optical couplers based on gap plasmon waveguides. The structure consists of rectangular gap Plasmon waveguides in metal films. It is clear that the wave number and correspondingly light confinement and the loss in the waveguides are the most effective parameters in power coupling. Some dependencies of the maximum transfer power on the structure parameters are shown. Simulation results are obtained by the compact-2D finite-difference time-domain (FDTD) method and we could comply them with the results obtained by an analytic method. The considered structures, because of their small coupling length and dimensions are appropriate for use in optical integrated circuits.