Silica-Hafnia Erbium-Activated Planar Waveguides

Silica-based sol-gel waveguides activated by Er3þ ions are attractive materials for integrated optic devices. 70SiO2-30HfO2 planar waveguides, doped with Er3þ concentrations ranging from 0.01 to 4 mol%, were prepared by sol-gel route. The films were deposited on v-SiO2 and silica-on-silicon substrates, using dip-coating technique. The waveguides show a homogeneous surface morphology, high densification degree and uniform refractive index across the thickness. Emission in the C-telecommunication band was observed at room temperature for all the samples upon excitation at 980 nm. The shape is found to be almost independent on erbium content, with a FWHM between 44 and 48 nm. The 4I13=2 level decay curves presented a single-exponential profile, with a lifetime ranging between 1.1 and 6.7 ms, depending on the erbium concentration. The waveguide deposited on silica-on-silicon substrate supports one single propagation mode at 1.5 lm with a confinement coefficient of 0.85, and a losses of about 0.8 dB/cm at 632.8 nm.