<title>Second harmonic generation in electrically poled TeO<formula><inf><roman>2</roman></inf></formula>-based glasses</title>

Abstract

Optical second harmonic intensity has been measured for electrically poled several TeO2- based glasses in order to discuss relation between second harmonic intensity and glass structure. The glass systems, ZnO-TeO2, BaO-TeO2, WO3-TeO2 and ZnO- BaO-TeO2, have been chosen because these systems possess relatively extended glass- forming region. The second harmonic intensity increases with an increase in the concentration of ZnO in the binary ZnO-TeO2 system. It is known that an addition of ZnO to TeO2 glass converts TeO4 trigonal bipyramids to TeO3 trigonal pyramids and leads to creation of non-bridging oxygens. We presume that these tellurite glass structural units, which are lacking in center of symmetry, are oriented to the direction of external dc electric field and that the orientation takes place more easily in the ZnO-rich glass because the glass-network structure is more flexible owing to the presence of trigonal pyramids and non-bridging oxygens. While the second harmonic generation is clearly observed in ZnO-TeO2 and WO3-TeO2 glasses, it does not occur in BaO-TeO2 glasses under the present poling conditions. We speculate that the orientation of structural units scarcely occurs in the BaO-TeO2 glasses because the external field mainly causes the electron polarization of Ba2+ ions.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.