FABRICATION TECHNIQUES OF LITHIUM NIOBATE WAVEGUIDES.

Abstract

In the paper, the most commonly used fabrication techniques of optical waveguides in lithium niobate are reviewed. Diffusion processes such as out-diffusion of lithium oxide from the crystal surface, in-diffusion of metals, ion exchange and proton exchange, and ion implantation are analyzed. The characteristics of LiNbO//3 optical waveguides prepared by the different technological procedures, are reported in relation with the fabrication conditions. High quality optical waveguides on lithium niobate can be produced by Ti in-diffusion in a dry O//2 atmosphere at temperatures above 100 degree C for long diffusion ties ( greater than 10 h). However, despite the large amount of research done in this field, correlations between optical properties and structural characteristics have not yet been established.