GLASS LOCAL-STRUCTURE AND OPTICAL NONLINEARITIES OF OXIDE GLASSES

The origins of the nonlinear indices and of the generation of the seco nd harmonic after poling in oxide glasses containing large proportions of TiO2 have been investigated. Within this scope, the geometry of ti tanium oxygenated sites in glasses of TiO2-NaPO3-Na2B4O7 and TiO2-K2O- SiO2 systems were previously determined by XAFS analysis [T. Cardinal, E. Fargin, Y. Le Luyer, G. Le Flem, L. Canioni, P. Segonds, L. Sarger , F. Adamietz, A. Ducasse, Nucl. Instr. and Meth. B 97 (1995) 169]. Ab initio estimates of the first and second order microscopic polarizabi lities for representative titanium oxygen clusters were obtained and t hen tentatively correlated to nonlinear optical properties of the glas ses. (C) 1998 Elsevier Science B.V. All rights reserved.