Sol-gel erbium-doped silica-hafnia planar and channel waveguides

Erbium activated SiO2 -HfO2 planar waveguides, doped with Er3+ concentrations ranging from 0.01 to 4 mol%, were prepared by sol-gel method. The films were deposited on v-SiO2 and silica-on-silicon substrates using dip-coating technique. The waveguides show high densification degree, effective intermingling of the two film components; and uniform surface morphology. The waveguide deposited on silica-on-silicon substrates shows one single propagation mode at 1.5mum, with a confinement coefficient of 0.81 and an attenuation coefficient of 0.8 dB/cm at 632.8nm.. Emission in the C-telecommunication band was observed at room temperature for all the samples upon continuous-wave excitation at 980 nm or 514.5 nm. The shape of the emission band corresponding to the I-4(13/2) --> I-4(15/2) transition is found to be almost independent both on erbium content and excitation wavelength, with a FWHM between 44 and 48 rum, The I-4(13/2) level decay curves presented a single-exponential profile; with a lifetime ranging between 1.1 - 6.6 ms; depending on the erbium concentration. Infrared to visible upconversion luminescence upon continuous-wave excitation. at 980 nm. was observed for all the samples. Channel waveguide in rib configuration was obtained by etching-the active film in order to have a well confined mode at 1.5 mum.