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.