Abstract
Random gain medium based on organic Rhodamine 590 (R590) laser-dye and Titanium dioxide (TiO2) suspended nanoparticles have been prepared with polymethylmethacrylate (PMMA) as a host. Spray-coated homogeneous film samples of 22.4 μm thickness. Optimum concentrations have been determined depending on the normal fluorescence spectra which give evidence that the laser dye provides amplification and TiO2 nanoparticles act as scatter center. At the optimum concentrations, results of the random gain medium under second harmonic Nd: YAG laser excitation shows that the values of bandwidth at full width half-maximum (FWHM) and the threshold energy are about 11 nm and 10 mJ respectively.
Highlights
Random lasers (RL) are unique sources of stimulated emission in which the feedback is provided by scattering in a gain medium [1,2]
Random laser effects have been observed in a variety of organic and inorganic gain media including powders of solid-state luminescent and laser crystals [3,4], liquid laser dyes with scatterers [5], polymeric films with and without intentionally introduced scatterers [6], ZnO scattering films and nanoclusters [7], dye-infiltrated opals [8], porous media infiltrated with liquid crystals with dyes [9] and many others
Random gain medium based on mixtures of suspended TiO2 nanoparticles of different concentrations and were mixed with Rhodamine 590 (R590) and the polymer PMMA was used as a host [16], from fluorescence measurements of the above concentrations, it was noticed that a TiO2 concentration of 10–4 mol/l had the highest intensity and the narrowest bandwidth for film samples
Summary
Random lasers (RL) are unique sources of stimulated emission in which the feedback is provided by scattering in a gain medium [1,2]. Random gain medium based on mixtures of suspended TiO2 nanoparticles of different concentrations and were mixed with R590 and the polymer PMMA was used as a host [16], from fluorescence measurements of the above concentrations, it was noticed that a TiO2 concentration of 10–4 mol/l had the highest intensity and the narrowest bandwidth for film samples. Chiad et al / Natural Science 4 (2012) 402-408 mum TiO2 nanoparticles concentration, the emission intensity spectra at different Nd: YAG pumping energies were investigated to determine the lasing threshold [17]
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