Near-stoichiometric LiNbO₃ optical waveguides fabricated using vapor transport equilibration and Ti co-diffusion

Near-stoichiometric planar and strip LiNbO₃ optical waveguides were demonstrated using vapor transport equilibrium process and co-diffusion of titanium metal. Optical confinement is better in z-cut substrates than in x-cut substrates, and the waveguides were characterized optically. Spectral measurements, such as OH^- absorption, optical absorption near the fundamental edge, and Raman scattering, were carried out to examine the Li-composition and crystalline phase inside and outside the guiding layer. The results have shown that the vapor transport equilibration process has brought these waveguides toward stoichiometric composition, the Li content inside and outside the waveguide layer is essentially identical, and the LiNbO₃ phase is still retained within the waveguide layer.