Emission sensitization processes involving Nd3+ in YAG

The paper investigates the characteristics of sensitization processes of Nd3+ emission in YAG ceramics under broad band pumping by co-doping with Cr3+ and the prospect of using Nd3+ and Cr3+ for sensitization of emission of Yb3+. It is evidenced that the energy transfer from Cr3+ to Nd3+ involves both direct and weak migration-assisted processes and is thus dependent on the concentrations of both species. It is also found that the ion-ion interaction responsible for the direct transfer contains besides the dipole-dipole coupling strong superexchange contribution that dominates the transfer to the Nd3+ ions up to the third coordination sphere and has major implication in sensitization. Investigation of (Cr, Nd, Yb)-doped YAG ceramics shows that Cr3+ can sensitize the emission of Yb3+ both via the chain Cr-Nd-Yb or by direct Cr-Yb energy transfer. The prospect of utilization of these processes in the solar-pumped laser is discussed.