Water Vapor Effects on Titanium Diffusion into LiNbO3 Substrates

This paper describes experimental studies on titanium diffusion into Z-cut LiNbO3 substrates as a function of water vapor content in the diffusion atmosphere of oxygen and argon. LiNbO3 crystal characteristics were found to depend mainly on water vapor content, while Ti-diffusion characteristics were found to be affected not only by water vapor content but also by the type of carrier gas. This study has important implications for the successful fabrication of Ti-diffused LiNbO3 waveguides; for oxygen carrier gas, a small amount of water vapor should be introduced, while for argon carrier gas, a medium amount of water vapor should be introduced.