Second Harmonic Generation induced by optical poling in new TeO2–Tl2O–ZnO glasses

New tellurite glasses with a large glass forming domain were elaborated within the TeO2-Tl2O-ZnO ternary system. The evolution of the glass transition (Tg) and onset crystallization (T0) temperatures for such tellurite glasses was studied, in particular, as a function of the Tl2O addition. A decrease of both Tg and T0 temperatures was observed; the former being more affected. Structural modifications induced by the addition of the modifiers were studied by Raman spectroscopy. For a fixed ZnO concentration, the increase in the Tl2O content leads to a destruction of the glass framework, characterized by the transformation of TeO4 disphenoids into isolated TeO3 2 trigonal pyramid-like ortho-groups. For a fixed Tl2O concentration, the ZnO addition induces similar effects on the glass structure. The optical transmission of the ((80 x)TeO2-xTl2O-20ZnO) (x = 10, 20 and 30 mol%) glasses was measured in the 300-2000 nm range. Their good transparency was evidenced and a clear reduction of the optical bandgap was noticed with the increase in the Tl2O content. Finally, Second Harmonic Generation was unambiguously detected for each glass composition. The second order non-linearity amplitude is found to be increasing as a function of the Tl2O concentration, in the tested range.