Spontaneous emission in a disordered dielectric medium

Abstract

We observed the change in fluorescence lifetime from a molecular dye embedded in a colloidal suspension of polystyrene spheres when the mean separation between spheres remains less than the wavelength of emission. At high densities of colloidal particles the spontaneous emission is inhibited, while as the density of colloidal particles is lowered the spontaneous emission is enhanced. This phenomenon is interpreted in terms of coherent interference from the electric field radiated by the molecular dipole and the reradiated field from the dielectric spheres.