Mode control of Ti-diffused LiNbO_3 slab optical waveguide

Abstract

The investigations were carried out on optical waveguides obtained by thermal diffusion of Ti into LiNbO(3) single crystals. In the Ti-diffused LiNbO(3) slab waveguides, the relationships of the refractive index profile (index change at the surface, diffusion depth) to various diffusion conditions were examined. Conditions were found to fabricate the waveguides of the required number of modes (TE modes) and effective indices for the wavelength of a He-Ne laser (0.6328 microm) and a GaAs-GaAIAs double heterostructure laser (DH laser) (0.8730 microm). The slab waveguides of the required number of modes and effective indices could be obtained by adjusting only the thickness of evaporated Ti film.