Cylindrical Plasmonic Waveguides With Cladding of Hyperbolic Metamaterials

We propose and analyze a new design of cylindrical plasmonic waveguides with the dielectric-coated metal wire as the inner core structure and the hyperbolic metamaterial as the outer cladding. The propagation characteristics of the plasmonic waveguides are analytically solved based on the dispersion relation of a multilayered anisotropic structure in cylindrical coordinates. By using the hyperbolic cladding on the core structure, a sufficiently confined mode area comparable to that of the metal cladding can be attained, while the propagation length is substantially increased. This character is attributed to the strong anisotropy of the hyperbolic cladding that offers an extra degree of freedom to adjust the balance between confinement and loss, leading to a better waveguide performance. A significantly improved figure of merit (the ratio of propagation length to mode size) is achieved for the plasmonic waveguides made of silver and zinc oxide at the telecommunication wavelength.