5th Young Researcher Meeting 2014 – Trieste
"Influence of the phosphorous precursors on the optical properties of SiO2-HfO2-P2O5 planar waveguides"
University of Trento, department of physics,
The needs for compact and efficient photonic devices obtained by rare earth-activated glasses, such as fibers and lightwave planar circuits, still drive the research of novel glass composition and optimized fabrication protocols. It’s demonstrated by a rich literature and by several devices present on the market that sol-gel processes can be effectively used for integrated optics. Miniature size and performances of integrated lasers and amplifiers are mainly linked to rare earth doping level, which must be maximized, without quenching the fluorescence of the doped material. Cross relaxation between neighboring erbium ions leads to the quenching of the fluorescence and toо fast de-excitation within erbium clusters. The clusters have the strongest influence on the decrease of the lifetime. Hence, it is important to eliminate them by dissolving the rare-earth ions into the glass matrix. A way to do this is to improve the silica glass matrix by adding co-doping agents, such as P2O5 or A12O3. We have already demonstrated that the silica-hafnia system is a viable route for the preparation of active waveguides by sol-gel approach. On the basis of that, we have investigated planar waveguides with compositions (70-x)SiO2-30HfO2 -хP2O5 (х= 5, 10 mol %), activated by 0.5 mol% Er3+ ions. Planar waveguides were fabricated by sol-gel method and dip-coating technique. The main attention was paid on the influence of different phosphorous oxides precursors, on the fabrication process and on the optical parameters. Prepared planar waveguides were characterized by modal spectroscopy, optical transmittance, time resolved photoluminescence measurements. This research is performed in the framework of MAE (2013–2015) and CNR-PAS (2014-2016) projects.