LITHIUM NIOBATE SINGLE CRYSTAL, OPTICAL ELEMENT USING THE SAME, AND METHOD FOR PRODUCING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a method for improving the element performance of a lithium niobate single crystal which has been expected as the material for optical elements because it has excellent optical properties and a single crystal having a large diameter and high uniformity of composition can be supplied relatively easily, but has been limited in the improvement of the element performance due to the congruent composition containing several percents of non- stoichiometric defects in the conventional commercial lithium niobate single crystals.

SOLUTION: The lithium niobate single crystal is grown from a melt having a composition containing Li more than the stoichiometric composition. The lithium niobate single crystal contains 0.1-3 mol% of at least one element of Mg, Zn, Sc and In. The lithium single crystal has a molar fraction of the formula: Li2O/(Nb2O5+Li2O) of from 0.490 to less than 0.500. The optical device using the lithium niobate single crystal and a method for producing the same are also provided.

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