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 I-4(11/2) level to the 1.5 mu m fluorescence emitting I-4(13/2) 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+: I-4(11/2); Ce3+: F-2(5/2)-->Er3+: I-4(13/2); Ce3+: F-2(7/2), 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 I-4(13/2): I-4(13/2)-->I-4(15/2): I-4(9/2), which lowers the population density of the I-4(13/2) manifold and causes a deleterious effect in the 1.5 mu m fluorescence intensity, is more severe in the sulfide glasses. Population feeding rate from the I-4(11/2) to the I-4(13/2) level is significantly enhanced by way of cerium codoping into tellurite glasses, which promises an efficient 980 nm pumped broadband Er3+-doped fiber amplifier. (C) 2000 American Institute of Physics. [S0021-8979(00)06620-2].