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 TeO32− 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 band-gap 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.