Emission decay rate of a light emitter on thin metal films

We theoretically study the emission decay rate of a light emitter on thin Au films based on a semiclassical point-dipole model. The complex dielectric functions of Au films determined by spectroscopic ellipsometry are used in this calculation model. We investigate the dependences of the decay rate on the metal thickness, distance between emitter and metal, and emitted-light wavelength. It is found that the decay rate shows a peak at the surface plasmon resonance wavelength. It is also shown that its peak wavelength, width, and peak value are strongly dependent on the Au layer thickness. The peak value in the decay rate versus wavelength curves for the Au film of 10 nm thickness is also found to be higher than for the bulk Au metal. These results are due to the metal-thickness-dependent plasmon effects on the emission decay rates.