Optical waveguides are fabricated by thermal diffusion of Ti into Y-cut $LiNbO_3$ single crystals.
Two strip waveguides are prepared by diffusion of approximately 1000-Å of Ti at 980℃ in flowing argon bubbled through water for 12h. and the samples are reoxidized in flowing oxgen for 2h. The multimode electro-optical switching effect is observed between two 30-㎛-wide strip waveguides. Electrode capacitance is measured to be 40 pF, which implies a possible bandwidth of 700㎒ for a 50Ω load.
SEM measurement (analyzed by EDAX) of the polished surface of Ti-diffused slab waveguide indicates the thermal diffusion of Ti into $LiNbO_3$ substrate.