Bow-Tie Hybrid Plasmonic Waveguides

Abstract

We propose a hybrid plasmonic waveguide that incorporates a semiconductor—insulator–metal bow-tie configuration within a low-index gap guarded by semiconductor and metallic nanostructures. Ultratight field confinement ( $A_{{\rm eff}} \sim \lambda ^2 /3100 - \lambda ^2 \!/\!120$ ) in conjunction with reasonable propagation distance ( $L \sim$ 56-138 μm) can be achieved simultaneously at a telecommunication wavelength. Compared to a conventional hybrid waveguide, the effective mode area and propagation loss of a typical bow-tie hybrid configuration are reduced by 2–89% and 34–62%, respectively, whereas the figure of merit is enhanced by 53–700%, along with increased power ratio inside the gap region for small gap cases. Studies on fabrication tolerance, waveguide crosstalk, and loss compensation reveal its robust property for practical implementations and remarkable feasibility to realize ultracompact passive and active components. Moreover, we also reveal the broadband feature of the waveguide and show that its concept can be applicable to various other metallic configurations as well, which may open up possibilities for the inventions of numerous high-performance plasmon waveguides and components.