Tunable random laser in capillary with Nile red solution and TiO2 nanoparticles

Abstract We report a tunable random laser in Nile red (NR) solution with TiO2 nanoparticles. The good lasing characteristics of NR and random scattering environment provided by TiO2 bring excellent random laser emission. We analyze the influence of TiO2 number density to the threshold of random laser and draw the output energy stability via pump time. Furthermore, considering the solvatochromism of NR, the solvent is substituted by ether and acetone while the optimal number densities of TiO2 in each system are obtained respectively. In addition, we use sulfuric acid to change the polarity of the sample and obtain the random laser spectra that change continuously with the polarity of the solution. This combination of NR and TiO2 could shed new light upon the generation and tuning of random laser.