Photorefractivity in SiO2 : SnO2 glass-ceramics by visible light

SnO2-SiO2 nanostructured glass-ceramics were investigated to verify the suitability as photorefractive material with sensitivity to the visible light. The material was obtained by a sol-gel method and the composite structure was analyzed by means of transmission electron microscopy and Raman scattering. Optical absorption measurements from 200 to 800 nm were analyzed to estimate the effective energy released in the material by laser exposure. Negative refractive index changes (up to -10(-3)) were observed after exposure to laser beams from the ultraviolet to the green visible spectral range (at 266, 458 and 532 nm). The absorption of visible radiation has larger yield of refractive index change compared to ultraviolet radiation. The results are consistent with the proposal that the refractive index changes involve interface defect states at the surface of SnO2 clusters with nanometer dimensions. (C) 2003 Elsevier B.V. All rights reserved.