Abstract
This paper reviews the following aspects sometimes encountered in fabricating Tiindiffused LiNbO3 optical waveguides; i) Li2O outdiffusionyielding the degradation of a light confinement in resultant optical waveguides, ii) modulation drift phenomenon under a dc bias resulting in an output light level degradation, and iii) ferroelectric depolarization in a Ti diffused +c face of the substrate. The two formers are quite serious problems for obtaining high quality Ti diffused stripe optical waveguides and devices, and the later is an unexpected aspect in fabricating electrooptic waveguide devices.
Improvement techniques for these features, appeared in recent papers, are considered, and authors' recent results are also described. The examined techniques up to date are not sufficient, and further efforts to establish them should be required.
