Optical and fluorescent properties of Y₂O₃ sol–gel planar waveguides containing Tb³⁺ doped nanocrystals

Abstract

Terbium doped Y₂O₃ planar waveguides were fabricated by sol–gel process and dip-coating using yttrium acetate as precursor. Two different doping modes were compared, i.e. introduction in the sol of dispersed Tb³⁺ions from dissolved Tb(NO₃)₃, or of nanoparticles of Tb₂O₃ or [Y₂O₃:50% Tb] from an alcoholic suspension. The chemical and nanostructural properties were analyzed by infrared spectroscopy, transmission electron microscopy and X-ray diffraction. The Tb³⁺ fluorescence properties were studied as a function of temperature and atmosphere of the thermal treatments, and of the Tb³⁺ concentration. The fluorescence properties are discussed in relation to the quenching mechanisms induced by Tb⁴⁺ transformation, residual OH groups, and crystallites size and structure. Optical propagation losses of the Tb doped Y₂O₃ planar waveguides related to the doping modes and Tb³⁺ concentration are presented. Doping sol–gel films by nanoparticles is shown to be a valuable alternative to the conventional doping from dissolved terbium salt.