Relationship between structure and optical properties in rare earth-doped hafnium and silicon oxides: Modeling and spectroscopic measurements

The SiO2-HfO2 binary system is recognized as a promising candidate for Erbium-doped waveguides amplifiers fabrication. Recently, it was demonstrated that Er3+-activated 70SiO(2)-30HfO(2) planar waveguides with valuable optical and structural properties can be prepared by sol-gel technique with dipcoating processing. The important role played by hafnium in the silica network was evidenced by the particular spectroscopic properties presented by Er3+-ions in the silica-hafnia planar waveguides. In this work we present preliminary results on HfO2-SiO2 bulk xerogels doped with Eu3+ ions, with the aim to go inside the role of hafnium on the rare earth ions local environment. Spectroscopic measurements of the Eu3+ photoluminescence emission are given. Numerical simulations by the molecular dynamics method have been performed showing clearly a phase separation for the HfO2 richer samples. Moreover it is found than the rare earth-doping ions stay preferentially in hafnium rich domains, thus explaining why the rare earth spectroscopic properties are strongly modified. (c) 2008 Elsevier B.V. All rights reserved.