Abstract: The expressions for the electric potential and electric field of infinite length two-layered cylinder are obtained by solving Laplace equation.Based on the scattering theory,we deduce the optical scattering,absorption and extinction efficiencies for two-layered cylinder,and calculate the far-field spectra and near-field distributions of Au nanotube.It is found that the calculated results are same as that obtained by Mie scattering theory.Thus,our theoretical results can be well used in the studies of nano-optics.

Key words: static electric field, Laplace equation, scattering, Au nanotube