Random laser action with nanostructures in a dye solution

Photoluminescence of Rhodamine B dye solution containing nanostructures of titanium dioxide (nanoparticles, nanorods, and nanotubes) was investigated at various optical excitation intensities. The stimulated emission was observed owing to multiple scattering of photons in the dye solution. The threshold intensity, emission wavelength, and profile of stimulated emission are different for different nanostructures. Single and double emission peaks were observed, respectively, at low (10−3 M) and high (10−2 M) dye concentrations. The stimulated emission characteristics with nanostructures dispersed in dye solution are attributed to the nonresonant scattering.