Erbium-activated monolithic silica xerogels and silica-titania planar waveguides: optical and spectroscopic characterization

Silica-based sol-gel glasses activated by Er3+ ions are attractive materials for integrated optical devices such as optical amplifiers operating in the 1.5 ?m band. In particular, the TiO2-SiO2 binary system is of technological importance because it offers the possibility of producing planar waveguides with a controlled refractive index depending on the TiO2/SiO2 molar ratio, and is a good compromise between performance and cost. In this lecture we present recent results obtained for Er2O3-SiO2 monolithic xerogels and erbium activated SiO2-TiO2 planar waveguides. Emission at 1.5 ?m is observed in all Er2O3-SiO2 samples upon CW excitation at 980 nm. A large spectral width of the emission band and a high quantum efficiency of the 4I13/2 level is observed for the Er2O3-SiO2: 5000 ppm system. Erbium activated monomode SiO2-TiO2 planar waveguides have a refractive index of about 1.58 at 632.8 nm, a thickness of about 0.5 ?m and an attenuation coefficient of 0.5 dB/cm at 632.8 nm on a propagation length of 3 cm. Emission of Er3+ ions in the visible region is observed upon excitation of the TE0 mode at 488 nm.