Design and Analysis of a Semi-Elliptical Ultra-Compact Nano-plasmonic Coupler

In this paper, we propose a novel design and demonstrate the analysis of a highly efficient three-dimensional nano-plasmonic semi-elliptical coupler between a dielectric waveguide and metal-dielectric-metal (MDM) plasmonic waveguides. Numerical simulation yields coupling efficiency up to ∼78% at the optical communication wavelength of 1550 nm. The dependence of coupling efficiency has been studied by changing the width of the plasmonic waveguide and the length of the semi-minor axis. Based on these results, the optimum dimensions of the semi-elliptical coupler have been determined. In both scenario, the transmission response of the proposed structure is found to be broadband. Using optimum dimensions, we have analyzed coupling efficiency, reflection coefficient, return loss and voltage standing wave ratio (VSWR) at a broad range of input signal wavelengths.