Spectroscopic properties and energy transfer in Ga2O3– Bi2O3–PbO–GeO2 glasses codoped with Tm3+ and Ho3+

This paper reports on the spectroscopic properties and energy transfer in Ga2O3–Bi2O3–PbO–GeO2 glasses doped with Tm3+ and/or Ho3+. From the optical absorption spectra of Tm3+, Judd–Ofelt intensity parameters, radiative transitions probabilities, fluorescence branching ratios, and radiative lifetimes have been calculated using Judd–Ofelt theory. The measured differential scanning calorimetry result shows that the glass exhibits excellent stability against devitrification with ΔT = 129 °C. The measured luminescence spectra show that the 3H4 → 3F4 transition of Tm3+ upon 808 nm laser diode excitation possess a broad full width at half-maximum of ∼126 nm. The maximum value calculated stimulated emission cross-section and the measured lifetime of 3H4 level from the 1.47-μm transition are ∼4.73 × 10−21 cm2 and ∼0.239 ms, respectively. It is noticed that codoping of Ho3+ could significantly enhanced the ratio of the intensity of 1.47–1.80 μm by energy transfer via Tm3+: 3F4 → Ho3+: 5I7.