Domain switching performance of stoichiometric LiTaO_3 for bulk quasi-phase matching devices

摘要

We grew near stoichiometric LiTaO_3 crystal from a Li-rich melt using a novel double crucible Czochralski method. The ferroelectric domain shape and domain wall smoothness were compared between the conventional and near stoichiometric LiTaO_3 crystals. It turned out that the domain shape under the electric field at room temperature strongly depended on the densities of nonstoichometric defects. The domain shape in the conventional LiTaO_3 is basically triangular while it is hexagonal in the stoichiometric LiTaO_3. The sides of hexagon in the stoichiometric LiTaO_3 are perpendicular to the crystallographical X axes, that is, parallel to the X faces. Therefore, considerably smooth domain walls can be obtain in the stoichiometric LiTaO_3 when the periodical domain structure is designed as each domain elongates along the Y axis. This result is promising a great improvement by using stoichiometric LiTaO_3 in fabricating quasi-phase matching wavelength conversion devices with high performances.