Random lasing from sulforhodamine dye-doped polymer films with high surface roughness

Active waveguides with high surface roughness due to phase separation in polymer blends can sustain wave-guided coherent random lasing, paving way to the development of integrated devices technologically and economically more favorable that the ones based on nanopatterning. In spite of the vast amount of work on organic thin film lasers carried out, the orange-red spectral region (600-700 nm) has not received much attention in this context, albeit it is of interest in biophotonic applications. In this paper, wave-guided coherent random lasing (RL) at 610 nm (Sulforhodamine B) and 630 nm (Sulforhodamine 640) is achieved by incorporating silsesquioxane nanoparticles into dye-doped polymer films. An AFM analysis concludes that the RL emission originates due to the scattering induced by the high surface roughness coming from the polymer/silsesquioxane phase separation. The reported results demonstrate that it is possible to get efficient and photostable laser emission from dye-doped thin films in the wavelength region over 600 nm by incorporating into the polymeric material appropriate nanoparticles which induce structural changes.