Erbium-doped GeO2–TiO2 sol–gel waveguides

90GeO2–10TiO2 sol–gel waveguides doped with 1 mol% Er were fabricated using TiCl4 as precursor for TiO2 and germanium ethoxide for GeO2. Films with residual porosity ⩾2% and with refractive index of 1.671 were obtained at annealing temperatures of 600 °C, because of the Tg of GeO2 glass and its 1.603 refractive index. X-ray diffraction measurements made on films heated at 600 °C showed no crystalline phase. The film composition evaluated from Rutherford backscattering spectrometry showed a decrease in the germanium content with respect to the nominal one. Information on the refractive indices and thickness of the films were obtained by a series of standard m-line spectroscopy measurements, carried out both in the TE and TM polarization. In the planar waveguides pumped at 514 nm, erbium showed fluoresce around 1530 nm with lifetimes of about 2.3 ms and a full width at half maximum of about 62 nm.