The optical properties of binary and ternary germanate glasses 40.3GeO2-59.7PbO, 31.3GeO2-26.8PbO-41.9Bi2O3 and 31.5GeO2-40.4PbO-28.1Bi2O3 (wt%) doped with Er3+ were investigated. The Judd-Ofelt intensity parameters were calculated and the near-infrared luminescence as well as the upconversion efficiency was analyzed. We observed that the ternary germanate glass containing the highest concentration of Bi2O3 presented the largest emission bandwidth for 4I13/2 → 4I15/2 transition and the highest infrared-to-visible upconversion efficiency among the samples studied. These results demonstrate that not only the presence of Bi2O3 but also the careful choice of its molecular weight plays a key role in optimizing parameters for using germanate glasses for photonics applications.
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We are indebted with C.B. de Araújo and A.S.L. Gomes for kindly sharing their equipments for luminescence measurements. The financial support from Brazilian agencies CNPq and FACEPE is acknowledged. W.L.B. thanks CLAF for his financial support.