Er³⁺ion concentration and annealing temperature effect on the fluorescence of Er³⁺:TiO₂planar waveguides prepared by the sol-gel process

The fabrication of Erbium-doped optical planar waveguides using the sol-gel process and the dip-coating procedure is described. The planar waveguides are optically pumped at room temperature using a Ti: sapphire laser with λ = 800 nm; the observed fluorescence of Er3+ ions at 1.53 μm is investigated. It is shown that the shape of the 4I13/2 → 4I15/2 transition depends on the concentration of Er3+ ions in TiO2 monomode waveguides (thickness = 80 nm), indicating that Er3+ ions modify the structure of TiO2 gel network. The dependence on heat treatment of Er3+ fluorescence spectra is investigated and preliminary lifetime measurements are presented. The elaboration of erbium-doped optical planar waveguides by the sol-gel process seems an inexpensive route for the realization of integrated devices on planar substrates.