Poling-induced structural change and second-harmonic generation in tellurite glasses

Poled TeO2-based glass, i.e., tellurite glass, exhibits second-harmonic generation (SHG). We discuss the relationship between structural change brought about by thermal and optical poling and induced second-order nonlinearity in tellurite glasses. It is known that for thermal poling the SHG-active region caused by poling is restricted within a thin layer beneath the anode-side glass surface. The thermal poling-induced structural change such as variation of structural units and incorporation of impure species on the anode-side surface are confirmed for ZnO-TeO2 and WO3-TeO2 glasses. On the other hand, for optical poling, change of valence state of vanadium is an important factor to induce SHG in vanadium-doped Nb2O5-TeO2 glasses.