Sol-gel planar waveguides for integrated optics

Er3+-doped silica-titania based planar waveguides with a composition 72SiO(2)-18TiO(2)-9AlO(1.5)-xErO(1.5)-yYbO(1.5) (in mol%) have been prepared by sol-gel processing, using multilayer spin-coating deposition on silica glass or silica-buffered single crystal Si substrates. Their optical properties were measured, including the measurement of the refractive index at 633 nm by ellipsometry, the optical loss by prism coupling at different wavelengths and the Er3+ fluorescence spectra and lifetimes at 1.54 mu m. The optical loss at 633 nm variedfrom ca. 0.7 to 1.0 dB/cm, the Er3+ emission at 1.54 mu m had a full width at half maximum of similar to 55 nm and the corresponding lifetimes varied between 3 and 6 ms, depending on the Er concentration and the residual OH level in the films, which was estimated by FTIR to be less than 200 ppm in the best cases. (C) 1999 Elsevier Science B.V. All rights reserved.