Transfer and backtransfer processes in Yb super(3+-Er) super(3)+ codoped Strontium Barium Niobate glass-ceramics

The forward and backward energy transfer processes in Strontium Barium Niobate glass-ceramics double doped with Yb super(3+ and Er) super(3)+ ions have been studied. In these samples the rare earth ions are incorporated into the nanocrystals with an average size of 50 nm. Using laser excitation at 950 nm is possible to excite selectively the Yb super(3+ ions and detect emission due to these ions (at 1040 nm) or combined with the Er) super(3)+ ions (at 980 nm). In previous works, the energy transfer processes between these ions in different matrices have been analyzed in order to improve the emission at 1550 nm, but these analyses are restricted to fast migration processes among ions. In this fast migration regimen the results are valid only for larger concentrations. However, in this work the dynamics of these transfer processes has been carried out using a general method called "transfer function model". The parameters which characterize these processes have been obtained and it has been possible to explain the important increase of the emission at 1550 nm due to the co-doping with Yb super(3+ ions. This analysis is valid for any range of doping concentrations.)