Dispersion relation of surface plasmon wave propagating along a curved metal-dielectric interface

The dispersion relations of surface plasmon wave (SPW) propagating along a convex or concave metal-dielectric interface with a radius of curvature are studied by solving the root of a characteristic equation in terms of Bessel and Hankel functions of complex order numerically. For the convex geometry, a metallic circular cylinder embedded in a dielectric host is modeled, whereas for the concave one, a dielectric cylinder in a metallic host is modeled. We found that the phase velocity of SPW along a convex interface is always less than that of SPW along a planar one. On the contrary, the phase velocity of a concave case is faster than that of a planar one. For both cases, the attenuation constants are larger than a planar one, due to the radial radiation of the energy into the surrounding medium, except the dissipation in the metal.