Preparation and infrared emission of silica-zirconia-alumina doped with erbium for planar waveguide
Résumé
The sol–gel synthesis of Er3+ (1–5%) doped silica(83)–zirconia(17) waveguide materials with addition of aluminum (6–20 at%) giving a FWHM (4I13/2–4I15/2)>60 nm is reported. Zirconia with high refractive index of 1.9 and low phonon energy is a good material compared with titania. The films were deposited on silicon or silica substrate by dipcoating technique using the precursors of Si(OC2H5)4 (Aldrich), Zr(C3H7O)4, CH3–CH(OH)–CH3, C5H8O2 , Al(NO3)3·9H2O, Er(NO3)3·5H2O and Yb(NO3)3·5H2O (Merck). The dipcoating rate of 2 and 3 mm/s were controlled by computer. Samples were calcinated at temperatures from 70 to 900 °C. The optical properties were studied by photoluminescent spectra and decay time. Influence of the Al3+ concentration and the heat treatment conditions for the Er3+ luminescent properties were studied. An energy transfer from 2F5/2 (Yb3+) to 4I11/2 (Er3+) multiplets is followed by a relaxation to the 4I13/2 (Er3+) and an efficiency luminescence of Er3+ (4I13/2–4I15/2) was clearly measured. It is interesting to indicate that the lifetime of few ms of Er3+ at 1530 nm in the sample Si(83)Zr(17)Al(6%)Er(1%)Yb(1%) is longer than for the sample without Yb ions. Multilayer thin films were prepared. The thickness, refractive index, the roughness about 2 nm and a propagation loss<2.5 dB/cm were studied for active planar waveguide applications.