Preform fabrication and drawing of KNbO3 modified tellurite glass fibers

For fiberization of tellurite glasses the 70TeO2–25ZnO–5Na2O composition is selected based on its good thermal stability and refractive index compatibility with most of the ferroelectric oxides. A modified built-in casting method is used to fabricate preforms. The fiber drawn by the rod-in-tube technique consists of two layers of cladding glass and a core with 5 mol% ferroelectric KNbO3. In this study we also address the low mechanical strength problem with tellurite glass fibers, by subjecting the preforms to polishing and wet chemical etching. Apart from the fabrication methods, we also report here a selective core heat-treatment and ferroelectric phase crystallization in a low dimensional system.