Synthesis and optical properties of AlPO4 :Yb3+/Er3+ nanoparticles doped optical fiber preforms
Résumé
The present work focuses on the development of a new material for the achievement of Er-doped fiber amplifiers. In order to increase the efficiency of such optical components, we have applied an approach of material nanostructuration to glass synthesis and have fabricated an optical fibre preform based on a pure silica matrix doped with AlPO4:Yb/Er nanoparticles (NPs). The aim of this approach is first to use Yb3+ ions as a sensitizer for Er3+ ions, so as to increase pump absorption. Secondly, AlPO4 structural units are known to (i) have geometrical properties similar to the tetrahedra of pure silica glass, (ii) increase ions solubility, (iii) reduce radiation-induced optical losses in Er-doped fibers and photodarkening phenomenon in Yb-doped fibers. A rare-earth-doped precursor synthesized by soft chemistry was used for solution doping of a silica optical fibre porous preform elaborated by modified chemical vapour deposition method. The preform was then sintered and collapsed as is done for industrial manufacturing. Structural characterization of the core material was performed by Raman and transmission electron microscopy and has shown the presence of Yb3+/Er3+-doped AlPO4 NPs with a diameter of 2-10nm. Optical spectroscopic studies have put in evidence the energy transfer between the Yb3+ and Er3+ ions. As compared to a direct excitation of Er3+ ions, an increase in the intensity of the 1.55µm emission by a factor 10 is observed when excitation is performed via Yb3+ ions.