Surface-plasmon-enhanced radiation effects in confined photonic systems

Combined action of a resonant cavity and metal nanocomposites is shown to r esult in dramatic enhancement of spontaneous emisson rate in the optical sp ectral range. The cavity leads to modification of the optical density of st ates (Purcell effect), whereas the metal nanoparticles lead to giant local- field effects in spontaneous emission occuring because of surface-plasmon-e nhanced vacuum field fluctuations. It is also shown that the surface-plasmo n resonances may result in a full photonic gap in a metal-dielectric compos ite, even for a completely random structure of the composite. In our experi ments, lasing at extremely low pump intensities, below 1 mW was observed fo r a novel class of optical materials, microcavities doped with fractal aggr eates of metal nanoparticles.