Producing channel waveguides requires a photolithographic mask, but the standard technique of using thermally evaporated metal films for proton exchange has proved to be unsuitable for withstanding the rather aggressive process of reverse proton exchange. We report the fabrication of a nonstoichiometric silica mask by ion-plating plasma-assisted deposition. This mask is strong enough to resist both direct and reverse proton exchange and is also compatible with anisotropic dry etching for patterning the mask and with electric field poling. Our technique is a practical alternative to the use of SiO<sub>2</sub> sputtered masks.
© 2004 Optical Society of America
Antonino Parisi, Alfonso C. Cino, Alessandro C. Busacca, and Stefano Riva-Sanseverino, "Nonstoichiometric Silica Mask for Fabricating Reverse Proton-Exchanged Waveguides in Lithium Niobate Crystals," Appl. Opt. 43, 940-943 (2004)