Growth of epitaxial thin films in the KTiOPO4 family of crystals

Abstract

Abstract We report the growth of thin (4–20 μm) epitaxial films of KTiOAs x P 1− x O 4 on KTiOPO 4 substrates. The films were grown at ∼ 850°C by liquid phase epitaxy using the tungstate and the pure arsenate-phosphate self-fluxes. Typical growth rates are ∼ 50–100 A/s, although rates as slow as 10 A/s have been observed. The orientations of these films are {011}, {100}, {110} and {201}, and no significant variation in their growth properties was observed. Unlike epitaxial films obtained by the ion-exchange process, these films possess a step-like refractive index profile which makes them especially attractive for micro-optical devices for frequency conversion applications. The large refractive index change, δn = n film − n substrate ∼ 0.01–0.02, and thegood optical quality of these films allows us to readily demonstrate optical waveguiding. We also report on results of other related material systems, and address the problem of lattice matching in the growth of these films.