1Low threshold random lasing in dye-doped silica nano powders.

Random laser action is demonstrated in two kinds of powder samples containing rhodamine 6G (Rh6G) doped SiO2 nanoparticles which are either directly dispersed within pure silica particles or embedded in a silica gel matrix which is subsequently ground. Both organic-inorganic hybrid materials present different laser thresholds and emission features which are systematically studied and compared. The dependence of the emission kinetics, emission spectrum, random laser threshold and slope efficiency on the dye doped nanoparticles concentration is investigated in both cases.