Effects of submicrometer-sized particles on microdroplet lasing.

We report the threshold emission characteristics of lasing from microdroplets that consist of Rhodamine 6G dye in an ethanol solution that contains undoped polystyrene latex spheres. The addition of latex particles to the droplets suppresses lasing. Our findings indicate that, for a fixed Rhodamine 6G concentration and fixed pump intensity, lasing ceases when a certain total-threshold latex particle surface area is reached in the droplet, independent of latex particle size. A possible explanation for these findings is the Förster-assisted annihilation of Rhodamine 6G dye lasing levels, facilitated by the adsorption of dye molecules on the surfaces of latex particles.