Fabrication techniques of lithium niobate waveguides

摘要

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 analysed. The characteristics of LiNbO/sub 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/sub 2/ atmosphere at temperatures above 1000 degrees C for long diffusion times (<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.