Localized surface plasmon resonance properties of elliptical gold nanotubes

The effects of ellipse shape, polarization direction of incident light, shell thickness, and dielectric constants of core and embedding medium on the localized surface plasmon resonance (LSPR) of elliptical gold nanotube have been investigated by the Finite Difference Time Domain (FDTD) method. When the semimajor axis is fixed, it is found that with the increase of the semiminor axis of the ellipse the extinction peak of the gold nanotube has a red-shift. With the increase of the angle between the incident polarization and the semimajor axis, the extinction peak has a red-shift. With the shell thickness decreasing, the extinction peak of gold nanotube also has a red-shift. Furthermore, we also find that the increase of the dielectric constant for core or embedding medium will induce a red-shift of LSPR in gold nanotube. The change of the extinction peak is ascribed to the plasmon hybridization and the competition between the variations of conduction and oscillation electrons.