Because of their remarkable characteristics single crystalline fiber crystals receive an intense study. The growth of single crystals fibers is of low cost in comparison to Czochralski or Bridgman techniques. In addition, by micro-pulling down technique it is possible to grow fiber shape close to final geometry to be used in the final component.
Yb-doped LiGd(WO4)2double tungstate crystal exhibit large absorption band and emission bandwidth. In spite of the optical performances of this material, only very few works were reported about single crystals fibers growth of Yb-doped LiGd(WO4)2.
Therefore, the main topic of this presentation is to investigate the fibers crystal growth from the melt of Yb3+:LiGd(WO4)2 using micro-pulling down (µ-PD) technique. The structure and spectroscopic characteristics of the single crystals fibers were evaluated to develop laser components based on active fiber shape. We have extended our research program to Yb3+-doped LiGd1-xLux(WO4)2 system to determine the solid solution range as a function of Lu3+ on Gd3+ sites.
Under stationary stable regime Yb3+-doped LiGd1-xLux(WO4)2 transparent and uniform single crystals fibers were grown by micro-pulling down technique. For x≤0.025, homogeneous fibers of diameter 700 µm were grown from the melt. The crystallization interface was flat, the meniscus length reach 150µm ± 20 and the liquid flow in the molten zone is laminar. For x ≥ 0.5 the melt is not congruent and the grown materials were ceramic.
The Yb dopant distribution was examined parallel and perpendicular to the growth direction. For x≤0.025 the dopant distribution along the growth direction is homogeneous and no significant segregation has been observed. The pulling rate did not significantly affect Yb distribution. The absorption, Raman and excitation spectroscopy at room temperature were performed to investigate the lattice changes due to the Lu3+substitution in the LiGd1-xLux(WO4)2 host.
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