Silica-based sol-gel optical waveguides on silicon

Silica-based waveguiding layers readily obtained by the spin-coating appropriate sols on silicon wafers. They easily be doped with rare earth elements, intended applications such as lasers or amplifiers. The authors describe the preparation and characterisation of such films. The film structure was investigated by X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopies (NEXAFS and EXAFS) and Fourier transform infrared spectroscopy (FTIR). Their surface area, evaluated by Brunauer-Emmett-Teller (BET) analysis, and their porosity, estimated from refractive index measurements, are reported. Finally, rare earth fluorescence lifetime data are presented and interpreted