Er Doped GeO2-TiO2 Sol-Gel Waveguides

Erbium-doped optical waveguides have received growing interest over the last decade due to their multiple applications, e.g. in integrated lasers or amplifiers for telecommunications1.2. Research on amplifier materials has increasingly tumed to glass films. They are cheap to fabricate and suitable for high doping concentrations. Ge02-based glasses are interesting due to a lower Tg and phonon energy than Si02 based glass. Moreover Ge02 glass has high transparency iri the near infrared region and its high refractive index allows easy fabrication ofhighly confined waveguides. 90Ge0r10Ti02 sol-gel waveguides doped with lmol%Er were fabricated using TiCl4 as precursor for Ti02 and germanium ethoxide for Ge02. In fac4 it is know that metal alkoxides and metal chlorides react together trough non-hydrolytic reaction, allowing a better structural homogeneity of the sol3 o Well-densified films with high refractive index can be obtained at low annealing temperature (600°C), because of the low Tg of Ge02 glass and its high refracti ve index. X-Ray DiflÌaction '(X!ID) meas~emèìit;-m~de on filìns heated at 600°C ~howed ~~ · crystalline phase. The film composition evaluated from Rutherford backscattering spectrometry (RBS) was in good agreement with the nominai one. Moreover the profile concentration was uniform throughout the film thickness. 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. Films have a typical thickness of about 0.4-0.5 ?m and refractive index of 1.67 at 633 nm. In the planar waveguides pumped at 514 nm, erbium showed fluorescence around 1530 nm with lifetimes of about 2.3 ms and a FW AM of about 62 nm. Raman and propagation losses measurements are in progress to check the structure and waveguides properties of the films.