Silica-Based Sol-Gel Films Doped with Active Elements

The preparation of glassy films doped with rare earth ions is important for planar waveguide fabrication in active integrated optic devices. The sol-gel process is a promising route for the preparation of such films and the eventual overcoming of the problem of rare earth clustering. In the present work, both SiO2 and 90SiO(2)-10TiO(2) films were prepared by spin coating on silica glass or single crystal silicon substrates and they were doped with neodymium in a Nd/Si atomic ratio up to 15%, using NdCl3 as precursor. These films were subjected to selected heat treatments and their thickness and infrared spectra were measured. The refractive index and porosity were also determined for some of the samples. Visible absorption spectra were then measured in bulk gels, due to the insufficient optical path of the films.