Study on the local field enhancement of elliptical gold nanotube

The local electric field components of the elliptical gold nanotube are calculated based on the finite difference time domain (FDTD) method. It is find that when the wavelength of the incident light is just at a resonant wavelength, the local field enhancement of the gold nanotube reaches a maximum. The increase of the semiminor axis of the ellipse makes the distribution of the local field change from a distribution that is high in both sides and low in the middle part of the nanotube into a distribution that is uniform around the tube. With the increase of the angle between the incident polarization and the semimajor axis, the local electric field components increase rapidly. The increases of the dielectric constants for both the core and the embedding medium cause the local field around the nanotube to decrease.