Effects of Dielectric Anisotropy on Surface Plasmon Polaritons in Three-Layer Plasmonic Nanostructures

The effects of highly anisotropic dielectric on surface plasmon polaritons (SPPs) are investigated in several three-layer plasmonic nanostructures. Dispersion relations of SPPs in anisotropic-dielectric-metal (ADM), dielectric-anisotropic-metal (DAM), and metal-anisotropic-metal (MAM) structures are analytically derived. The numerical results in the visible indicate that, in ADM, the propagation length of a conductor-gap-dielectric mode is changed from 5.9 to 91 μm and its cutoff thickness from 83 to 7 nm with varying the optical axis, while in DAM, the influences of anisotropic dielectric are reversed on propagation length and cutoff thickness. In MAM, by tuning the optical axis, the light confinement of symmetry SPPs mode varies about 10 %. Further numerical calculations show that the above results induced by the anisotropy of dielectric can be extended to the telecommunication frequency. The improved mode properties may be used in plasmonic-based nanodevices and tunable single surface plasmon sources.