THEORETICAL-ANALYSIS OF THE DYNAMIC BEHAVIOR OF HIGHLY-EFFICIENT ERBIUM YTTERBIUM CODOPED FIBER LASERS/

A numerical study of the transient behavior of single-mode Er3+/Yb3+ c odoped fiber lasers is presented. The model, based on propagation-rate equations, includes both uniform upconversion from the I-4(15/2) and I-4(9/2) erbium levels and the pair-induced energy transfer process fr om ytterbium to erbium. We show that neglecting the z-dependence of th e operating fiber laser parameters allows accurate simulation results at minimum numerical effort, Using this numerical model, we characteri ze the laser relaxation oscillations and the effect of ytterbium on th e dynamic behavior and stability with respect to fluctuations of the p ump power. Our results confirm that the presence of Yb3+ enhances the efficiency of the laser and show that its stability is also significan tly improved.