Lithium niobate single crystal thin film and production method thereof

Abstract

A lithium niobate single crystal thin film formed on a lithium tantalate substrate, in which the a-axis lattice constant of the lithium tantalate substrate and the a-axis lattice constant of the lithium niobate single crystal thin film are lattice matched. To achieve the lattice matching, the lithium tantalate substrate is contacted with a molten composition to epitaxially grow a lithium niobate single crystal thin film, the molten composition mainly comprising Li.sub.2 O, V.sub.2 O.sub.5, Nb.sub.2 O.sub.5, Na.sub.2 O and MgO, whereby the a-axis lattice constant of the lithium niobate single crystal thin film and the a-axis lattice constant of the lithium tantalate substrate are matched to each other. With this arrangement, a lithium niobate single crystal thin film with large thickness and low propagation loss can be obtained without poling, which could not be obtained with prior art methods, thus greatly contributing to the optical device industry.

Dependencies are inferred from the claim text.