Synthesis, characterization and local changes induced by a cw argon laser in silica glass xerogel doped with transition metal ions

We report on the synthesis, characterization and local changes induced by a cw argon laser in SiO2 xerogel doped with low metal ion concentrations, and obtained by the sol–gel process. The V, Mn and Cr metal ions were introduced into the SiO2 matrix as inorganic salts and as an oxide in the case of Mo. The characterization of these materials showed that an amorphous system with high porosity was obtained; the metals were incorporated as ions with several different oxidation states, and the thermal diffusivity was around 10−9 m2/s. In these xerogel monoliths it is possible to induce local changes in the refractive index with the incidence of a focused laser beam at 488 nm, about 80 μm in diameter, with power intensities from 1 to 48 mW and an incidence time from 0.5 to 5 min. After this process, a high contrast in the transmitted light between the processed area and the homogenous matrix is obtained, resulting in an optical memory effect.