Fabrication and Characterization of Sol-Gel GeO2-SiO2 Erbium-Doped Planar Waveguides

GeO2-SiO2 sol-gel planar waveguides doped with Er were deposited by spinning on silica substrates. P2O5 or Al2O3 were used as co-dopants to improve erbium dissolution in the GeO2-SiO2 matrix. Multilayer amorphous films were obtained at 600 or 700°C. Er ions in the planar waveguide pumped at 980 nm showed fluorescence features around 1530 nm. Narrow fluorescence spectra (~20 nm) and long lifetimes (~6 ms) were found in P2O5 co-doped samples, whereas Al2O3 co-doping gave wider spectra (~50 nm) with slightly lower lifetimes (~5 ms). The quenching concentration in the Al2O3 co-doped samples was 0.9 mol% Er. Heat treatments in CCl4 improve the active properties and the addition of Yb enhances the pump absorption efficiency.