Optical properties of elliptical gold nanotubes with a nonconcentric core

Abstract:

Based on the finite difference time domain method, the effects of geometrical parameters, refractive indices of core and embedding medium and polarization directions of incident light on the optical properties of elliptical gold nanotubes with a nonconcentric core are investigated. The results show that when the polarization direction of the incident light is parallel to the long axis of the elliptical section, with the increase of kernel offset, higher order peaks appear and red shift in the extinction spectra, moreover, a new gradually increasing peak appear in the longer wavelength region. The new peak red shifts and its intensity increases with the increases in nanotube overall size and refractive index of core material, but the intensity decreases as refractive index of embedding medium decreases, the peak blue shifts and its intensity decreases with the increase in the short axis, the other peaks change differently as well. Furthermore, with increasing the angle between the polarization direction of the incident light and the long axis, the extinction peaks red shift.