IMPROVED COMPOSITION FOR SOL-GEL RARE-EARTH-DOPED PLANAR WAVE-GUIDES

A multilayer sol-gel process has been developed in order to make highl y doped rare-earth planar waveguides on silica or silicon substrates. Starting with a small range of constituents, such as SiO2, TiO2, P2O5 and Al2O3, we show that a large variety of gel compositions, with diff erent spectroscopic behaviour, can be made when doped with rare-earths . We have doped the sol-gel films with neodymium and we have optimized their compositions by measuring the neodymium fluorescence lifetime. For a composition with 10 atom% of phosphorous, the lifetime evolution with neodymium concentration was studied and a quenching concentratio n was found at 1% of neodymium. We have also shown the strong influenc e of phosphorous or aluminium in the sol composition on the fluorescen ce lifetime, for a given neodymium concentration. First results on sim ilar planar waveguides, doped with erbium, are also presented. The sta bility of the fluorescence lifetime over a long period of time is an o ther important point to be checked for these new materials: the lifeti me evolution over a 9 months measurement period is presented.