The relationship between glass structure and poling-induced optical second harmonic intensity for ZnO-TeO2 glasses

Local ordering around Te and Zn atoms of ZnO-TeO2 glass systems is investigated by Te K and Zn K EXAFS using synchrotron radiation. Tellurium K EXAFS results suggest the coordination states of tellurium atoms are changed from TeO4 trigonal bipyramids to TeO3+1 polyhedra or TeO3 trigonal pyramids with increasing of ZnO. Zinc K EXAFS results indicate that the Zn atom has the second oxygen shell which locates at the distance of 0.222-0.228 nm. The second harmonic intensity of the poled glass samples was also measured. The compositional dependence of the second harmonic intensity is explained in terms of the structural change of ZnO-TeO2 glass with the addition of ZnO.