X-RAY-ABSORPTION FINE-STRUCTURE (XAFS) STUDY ON THE COORDINATION OF TE IN PBO-TIO2-TEO2 GLASSES WITH HIGH 3RD-ORDER OPTICAL NONLINEARITY

X-ray absorption fine structure (XAFS) analysis of the local environment of Te in PbO-TiO2-TeO2 glasses was performed with a purpose of examining the relation to high third-order optical non-linearity (chi(3) = approximately 10(-12) esu). Li2O-TeO2 glasses were also examined for a comparison. Extended X-ray absorption fine structure analysis revealed the change of Te coordination polyhedron from trigonal bipyramid to trigonal pyramid with the addition of PbO. However, the decrease rate of TeO4 on addition of PbO is smaller than that in the Li2O-TeO2 glasses with Li2O addition, which is ascribed to the smaller ability of PbO to donate oxygen to TeO4. Chi(3) of the PbO-TiO2-TeO2 glasses increased upon replacing TeO2 by PbO, but the change of Te coordination state on addition of PbO decreased chi(3).