Glass local structure and optical nonlinearities of oxide glasses

Abstract

The origins of the nonlinear indices and of the generation of the second harmonic after poling in oxide glasses containing large proportions of TiO 2 have been investigated. Within this scope, the geometry of titanium oxygenated sites in glasses of TiO 2–NaPO 3–Na 2B 4O 7 and TiO 2–K 2O–SiO 2 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 polarizabilities for representative titanium oxygen clusters were obtained and then tentatively correlated to nonlinear optical properties of the glasses.