An explicit form of the surface plasmon dispersion relation of a metallic nanotube with a nonconcentric core above a metallic substrate is presented, based on the separability of Laplace equation in bipolar coordinates. Three distinct plasmon mode frequencies (ω 0, ω +, and ω −) are found. Numerical results show ω + and ω − are variable with the geometrical characteristics of the system, while the value of ω 0 is always stable, when the dielectric permittivity of nanotube core, and dielectric between the nanotube and substrate are same.
