  In this paper, we design a dielectric-to-plasmonic slot waveguide mode
converter based on the hybrid silicon-gold taper. The effects of mode matching,
the effective index matching, and the metallic absorption loss on the
conversion efficiency are studied. Consequently, a metallic taper-funnel
coupler with an overall length of 1.7um is designed to achieve a very high
conversion efficiency of 93.3% at 1550 nm. The configuration limitations for
not allowing this mode converter to achieve a 100% conversion efficiency are
also investigated. Such a high-efficiency converter can provide practical
routes to realize ultracompact integrated circuits.
