Nonlinear Optical Effects In Surface Crystallized 0.50TeO₂–0.50 LiNbO₃ Glasses

Abstract

Ever since, Borrelli¹ has reported the fabrication of transparent glass-ceramics composed of ferroelectric NaNbO3 crystals, glasses and glass-ceramics have been considered as potential candidates for a variety of NLO applications. TeO₂-based glasses containing ferroelectric crystals have emerged as promising candidates for nonlinear optical (NLO) applications, in the recent past. Transparent TeO₂ glasses containing the crystalline phase of ferroelectric LiNbO₃, have been fabricated. Since, the refractive-indices of TeO₂-based glasses and LiNbO ₃ crystal are compatible, the scattering losses at the glass-crystal interface is considerably small, thereby making these glasses ideal candidates for optical applications. Komatsu and co-workers², based on their studies on the crystallization behaviour of TeO₂-Li₂O-Nb₂O₅ glasses, proposed the possibility of the fabrication of transparent TeO₂-based glasses containing ferroelectric LiNbO₃ microcrystallites. But the difficulty encountered, in fabricating transparent TeO₂-based glasses containing ferroelectric LiNbO₃ crystals, is the precipitation of an undesired non-transparent pyrochlore phase. Subsequently, Kim et al ³ reported the crystallization of LiNbO₃ in TeO₂-Li₂0-Nb₂0₅ glasses (with high Li⁺ content), by a two-step heat-treatment process. They have also prepared transparent tellurite glasses containing LiNbO₃ crystals using an incorporation⁴ method in which LiNbO₃ crystals have been directly dispersed in glasses of the composition 80 TeO_2–15 Li₂O–5Nb₂O₅. Since a variety of applications of these glasses are foreseen, a detailed investigation into TeO₂-LiNbO₃ glass-ceramics is imperative.