FLUORESCENCE OF ER3+ IONS IN TIO2 PLANAR WAVE-GUIDES PREPARED BY A SOL-GEL PROCESS

Erbium-doped optical planar waveguides are prepared by a sol-gel process and a dip-coating technique. The guides are optically pumped at room temperature using a Ti:sapphire laser with lambda=800 nm; the observed fluorescence of Er3+ ions at 1.53 pm is investigated. It is shown that the shape of the I-4(13/2)-->I-4(15/2) transition depends on the concentration of Er3+ ions in TiO2 thin films (thickness=80 nm), indicating that Er3+ ions modify the structure of TiO2 gel network. This effect is confirmed by waveguide Raman spectroscopy. The dependence on heat treatment of Er3+ fluorescence spectra is also investigated. Furthermore, it is worthy of note that titanium oxide (TiO2) has lower phonon energies (<700 cm(-1)) than silica oxide glass hosts, which is expected to provide an environment with lower non-radiative decay rates and consequently more favorable for 1.53 pm emission in erbium-doped planar waveguides. The optical planar waveguides of Er3+:TiO2 obtained are promising for the realization of integrated-optic amplifiers and lasers.