Hybrid Tube-Triangle Plasmonic Waveguide for Ultradeep Subwavelength Confinement

In this paper, a novel hybrid tube-triangle plasmonic waveguide (HTTPWG) is presented, which is composed of three high index dielectric nanotubes placed above an equilateral triangular metal with the center corresponding to the three vertices of the triangle. The strong hybridization coupling between silicon dielectric nanotubes and the metallic triangular wedge SPP enables enhanced field confinement inside the gap region as well as long propagation length. The ultrasmall deep-subwavelength effective mode area (λ 2 /4000) can be realized by gradual modification of the geometric size, which is one-order improvement compared to other hybrid waveguides. Meanwhile, the propagation length of HTTPWG can reach the same order of magnitude as others. Moreover, the effects of actual fabrication errors on the mode properties about HTTPWG indicate that mode properties are also quite tolerant to fabrication deviations. The proposed waveguide can be applied to subwavelength laser devices and optical integrated circuits.