2.0 μm Emission Properties and Energy Transfer between Ho3+ and Tm3+ in PbO—Bi2O3—Ga2O3 Glasses

Abstract
Emission properties of 2.0 μm fluorescence and the energy transfer between Ho3+ and Tm3+ in 57PbO·25Bi2O3·18Ga2O3 (mol%) glass codoped with Ho3+ and Tm3+ were investigated. Cross‐relaxation rates in Tm3+ increased approximately 5 times when the Tm2O3 concentration was increased from 1.0 to 1.5 wt%. Coefficients of the forward Tm3+→ Ho3+ energy transfer were about 15 times larger than those of the Tm3+← Ho3+ backward transfer. Analysis of the energy transfer and gain spectra indicated that the highest gain at the 2.0 μm wavelength region could be achieved from the glass with 1.5 wt% of Tm2O3 and 0.3 wt% of Ho2O3.