The reverse proton-exchange (RPE) process performed in different H<sub>x</sub>Li<sub>1−x</sub>NbO<sub>3</sub> crystalline phases of proton-exchanged and annealed proton-exchanged LiNbO<sub>3</sub> waveguides leads to remarkable optical and compositional modifications. Analysis of ordinary and extraordinary index profiles, correlated with concentration depth profiles in RPE samples subjected to different exchange and postexchange treatments, shows how buried-index optical waveguides in LiNbO<sub>3</sub> with symmetric mode and reduced fiber–waveguide coupling losses can be realized.
© 1998 Optical Society of America
(130.3130) Integrated optics : Integrated optics materials
(130.3730) Integrated optics : Lithium niobate
(230.7370) Optical devices : Waveguides
(310.3840) Thin films : Materials and process characterization
Yu. N. Korkishko, V. A. Fedorov, T. M. Morozova, F. Caccavale, F. Gonella, and F. Segato, "Reverse proton exchange for buried waveguides in LiNbO3," J. Opt. Soc. Am. A 15, 1838-1842 (1998)