Enhancement of energy relaxation rates near metal-coated dielectric cylinders

The electromagnetic modes and their field distributions are evaluated for a dielectric cylindrical structure embedded in another dielectric, with a thin metallic film at the cylinder/dielectric interface. These modes provide energy relaxation channels for excited dipole emitters located inside or outside the cylinder. Significantly, we find that the emission rate is sensitive to the magnitude of the electron density of the metallic film coating. For typical parameter values, we find large enhancements of the emission rate, which can be in excess of three orders of magnitude, relative to the case in the absence of the film, arising at specific ranges of electron density. The theory is shown to conform with known limits, including the high density (perfect conductor) limit and the large distance (unbounded bulk) limit. The implications of the predicted enhancement due to the metal coating for the purpose of guiding atoms within such microstructures are pointed out.