coupling between silicon waveguide and metal-dielectric-metal plasmonic waveguide with lens-funnel structure

Various photonic integrated components have been implemented by ultra-thin silicon-on-insulator (soi) waveguides; therefore, it is desirable to couple ultra-thin soi waveguides to plasmonic waveguides. in this paper, we present an ultra-thin soi waveguide to a metal-dielectric-metal plasmonic waveguide based on a lens-funnel structure consisting of truncated luneburg lens and metallic parabolic funnel. the lens is implemented by varying the guiding layer thickness. the effect of different parameters of the coupler’s geometry is studied using the finite-difference time-domain method. the 1.13-μm-long coupler improves the average coupling efficiency in the c-band from 66.4 to 82.1%. the numerical simulations indicate that the coupling efficiency is higher than 69% in the entire o, e, s, c, l, and u bands of optical communication.