We investigated the performance of random dye lasers based on metal-fluorophore distance to study the effect of plasmonics through localized surface plasmons. The silver nanoparticles were coated with various silica thicknesses and mixed with Rhodamine 6G in methanol solution to provide gain to the system. The samples were pumped by a Q-Switched Nd:YAG green laser with nanosecond-pulsewidth and the emission light was collected by a spectrometer. The overlapping of extinction spectra of silver nanoparticles/silver-coated silica nanoparticles with the absorption and/or fluorescence of Rhodamine 6G indicates the localized surface plasmon effects. Increasing the metal-fluorophore distance decreases the localized surface plasmon effects result in increase of lasing threshold and decrease of emission peak intensity.

We observe the enhancement of coherence due to localized surface plasmon resonance in random laser from gold nanoparticles. Higher coherence is obtained for random lasers with gold nanoparticles than with alumina nanoparticles.