Drawing of single-crystal and glass-clad lithium tantalate fibers by the laser-heated pedestal growth method

Abstract

Lithium tantalate (LT) single-crystalline fibers with various growth conditions were obtained using the laser-heated pedestal growth (LHPG) method. The fibers can be produced with a diameter down to 70 µm and tens of centimetres in length by using different pulling rates. Preliminary experiments also showed that the LT fibers can be electrically poled for quasi-phase matching. To facilitate wave propagation with low loss, glass-clad LT fibers were fabricated by a co-drawing LHPG method for the first time. A vacuum apparatus was developed to eliminate the bubbles from incongruent evaporation of lithium oxide during the drawing of the glass-clad LT fibers. The glass-clad fibers are classified into two different categories by the measurements of refractive index profiles. One is a step-index fiber and the other is a graded-index fiber. Both fiber types are multimode at present, but single-mode LT fibers could be fabricated with the high-precision control of the LHPG systems.