A study of nonlinear optical properties in Bi2O3-WO3-TeO2 glasses

A series of bismuth tungsten tellurite glasses were prepared and their densities, linear refractive indices and transmission spectra were measured. The optical bandgaps E-opt and Urbach energies E-e of glasses were obtained from ultraviolet absorption edges. Both the optical gap (E-opt) and the band tail (E-e) are behaving oppositely. As the value of E-opt decreases with increasing WO3 content, the degree of disorder increases which causes more defects or localized states resulting in deep localized in the bandgap with the tailing increased. Z-scan technique was carried out to investigate the third-order nonlinear optical properties of Bi2O3-WO3-TeO2 glasses. The third-order optical nonlinearity increases with decreasing the optical bandgap E-opt, since a increase of WO3 content can provide the non-bridging oxygen ion content. (c) 2008 Elsevier B.V. All rights reserved.