Optical properties and infrared-to-visible upconversion in Er3+-doped GeO2–Bi2O3 and GeO2–PbO–Bi2O3 glasses

Luminescence properties and upconversion studies of germanate glasses in ternary GeO2–PbO–Bi2O3 and binary GeO2–Bi2O3 systems containing Er2O3 (0.1–1.0 wt%) are presented for the first time. The Judd-Ofelt parameters found for these glasses are: Ω2 = 4.50 × 10−20 cm2, Ω4 = 1.55 × 10−20 cm2 and Ω6 = 0.69 × 10−20 cm2 for binary glasses and Ω2 = 4.44 × 10−20 cm2, Ω4 = 1.82 × 10−20 cm2 and Ω6 = 0.39 × 10−20 cm2 for ternary glasses. The refractive index of these glasses is found to be ∼2. The transition 4I13/2 → 4I15/2 is peaked at ∼1.53 μm and shows a radiative lifetime around 5 ms. Both systems exhibit similar emission cross-section at 1.53 μm around 0.8 × 10−20 cm2. Upconverted green emission at ∼530 nm (2H11/2 → 4I15/2) and ∼550 nm (4S3/2 → 4I15/2) and red emission at ∼668 nm (4F9/2 → 4I15/2) are observed under 980 nm cw excitation. Our results suggest that these glasses are promising candidates for applications in photonics.