Abstract
Glass transition temperature of ZnO-BaO-TeO2 glasses, which show optical second harmonic generation after the electrical poling, has been measured in order to discuss the relationship between second harmonic intensity and glass structure. The glass transition temperature decreases with a replacement of BaO by ZnO, indicating that the flexibility of glass structure increases with an increase in the content of ZnO. Hence, an orientation of ensemble of electric dipoles due to TeO4 trigonal bipyramid and TeO3 trigonal pyramid can take place more readily in the tellurite glass with high concentration of ZnO, leading to the high optical second harmonic intensity and large second-order nonlinear coefficient in the glasses with ZnO-rich composition. Furthermore, it is thought that preferential occurrence of electron polarization of Ba2+ hinders the orientation of tellurite structural units when the external electric field is applied. The very low second harmonic intensity of poled 15PbO⋅85TeO2 glass supports this speculation.
