Fabrication and characterization of Er3+-doped GeO2–PbO and GeO2–PbO–Bi2O3 glass fibers

Glass fibers were drawn from GeO2–PbO–Bi2O3 and GeO2–PbO melts previously doped with Er3+. From the differential thermal analysis curve, the glass transition temperature was determined to be 420 °C, and no crystallization peak was observed in the temperature range of that analysis, indicating stability with regard to devitrification. Raman spectroscopy was performed to characterize the structure of the glasses, which exhibited large transmission windows (0.5–5.0 μm) and large refractive indices (∼2.0). Infrared to visible upconversion of Er3+ was observed in the fibers. The visible emissions were related to the upconverted green emissions at about 530 nm (2H11/2 → 4I15/2) and 550 nm (4S3/2 → 4I15/2), and red emission at 668 nm (4F9/2 → 4I15/2) under 980 nm excitation. The infrared transition (4I13/2 → 4I15/2) was peaked at 1.53 μm. The results obtained suggest that the fibers exhibit the same structures as the parent glasses and can be used in upconversion fiber optical devices.