Synthesis and spectroscopic properties of silica nanoparticles as scatter centers in random gain porous media

In this work, silica matrices have been synthesized and used as host for silica nanoparticles doped with Kiton Red laser dye using sol-gel technique. The bulk samples of KR-SiO2 nanoparticles confined in silica xerogel matrix have been prepared as a function of SiO2 nanoparticle sizes and concentrations. Different SiO2 particle sizes have been obtained by varying the pH value of starting silica precursor sol and determined using field emission scanning electron microscope. The structural characteristics of such matrices have been determined through FTIR spectra. Amplified spontaneous emission, threshold pumping energy, and mean free path for photons in the prepared random gain media have been reported. As a result, the best values of FWHM and threshold pumping energy, 8.7 nm and 12 mJ, have been observed for the sample prepared with 33.4 nm size and 2 wt% concentration of SiO2 nanoparticles. Comparison between the intensity of normal fluorescence spectrum (excited with CW laser diode 532 nm) and ASE spectrum (excited at 40 mJ pumping energy of 2nd harmonic Nd: YAG pulse laser 532 nm), Relation of both the bandwidth at FWHM and the peak fluorescence intensity as a function of pumping energy, Eth is the pumping threshold energy. [GRAPHICS] .