Plasmonically enhanced diffusive and subdiffusive metal nanoparticle-dye random laser

We report on surface plasmon (SP)-enhanced random laser emission from a suspension of silver nanoparticles in a laser dye operating at diffusive and subdiffusive scattering strengths. SP resonance enhances the scattering cross section, while the geometrical cross section remains small, thus providing a large gain volume. The localized electromagnetic field near the particle surface leads to enhanced absorption of excitation light and larger amplification of fluorescence. The metal-nanoparticle-based random laser yields larger linewidth narrowing at lower pump fluence threshold than a dielectric-scatterer-based random laser under equivalent conditions. These findings open the door to studies of applications related to light amplification assisted by SP in metallic nanoparticles. (C) 2005 American Institute of Physics.