Comparative study of energy transfers from Er3+ to Ce3+ in tellurite and sulfide glasses under 980 nm excitation

Abstract

We have demonstrated that the population feeding from the I11/24 level to the 1.5 μm fluorescence emitting I13/24 level of Er3+ ions in low phonon energy glass hosts can be enhanced by codoping with Ce3+ under optical pumping at 980 nm. The nonradiative energy transfer Er3+: 4I11/2; Ce3+: 2F5/2→Er3+: 4I13/2; Ce3+: 2F7/2, occurs in the form of phonon-assisted energy transfer, and therefore the feeding rates are faster in the tellurite glasses, which have a comparatively higher phonon energy than in the sulfide glasses. The cross-relaxation process for I13/24: 4I13/2→4I15/2: 4I9/2, which lowers the population density of the I13/24 manifold and causes a deleterious effect in the 1.5 μm fluorescence intensity, is more severe in the sulfide glasses. Population feeding rate from the I11/24 to the I13/24 level is significantly enhanced by way of cerium codoping into tellurite glasses, which promises an efficient 980 nm pumped broadband Er3+-doped fiber amplifier.