Formation of lithium niobate-tantalate waveguides

Low loss diffused lithium niobate-tantalate waveguides exhibiting strong electrooptic coefficients have been made by a simple processing procedure. The formation of these waveguides takes place by the conversion of a Nb metal film to Nb oxide at a low temperature, followed by diffusion of Nb into the LiTaO₃ substrate at about 1100°C. The diffused layer has a Gaussxan composition profile. Its measured refractive index is consistent with that calculated by interpolation between the indices of LiNbO₃, and LiTaO₃. The research reported in this paper was jointly sponsored by the Office of Naval Research, Arlington, Virginia and RCA Laboratories, Princeton, New Jersey. This paper is based on a presentation at the Conference on Preparation and Properties of Electronic Materials, Boston, Massachusetts, September 1974.