Luminescence Characteristics of Ho3+/Tm3+ Co-Doped Bi2O3–GeO2–Ga2O3–Na2O Laser Glasses

Abstract

The Ho3+/Tm3+ co-doped 35Bi2O3–40GeO2–15Ga2O3–10Na2O laser glass was synthesized by high temperature melting method. The 2.0 μm luminescence characteristics of system glass under central wavelength of 808 nm pumping light excitation were researched, and the fluorescence intensity changing with the doping concentration of Ho3+ was analyzed at Tm3+ content of 3-mol%. The results indicate that the 2.0 μm luminescence of Ho3+ is remarkably changed due to the doping ratio of Ho3+/Tm3+. The fluorescence intensity was achieved for the lase glass in the system when the sensitization ratio of Ho3+/Tm3+ is 0.5:3 mol%. Its maximum emission cross-section at 2.05 μm reaches 7.32 × 10−21 cm2, while the gain characteristic of σemi × τrad value can get 35.50 × 10−21 cm2 · ms, and the gain coefficient achieves 2.30 cm−1. Furthermore, the Gaussian decomposition method was employed to fit the spectrum of host glass, maximum phonon energy is 812 cm−1. It indicates that the host gets small phonon energy which is benefit to the 2.0 μm laser emission. In summary, results purport that Ho3+/Tm3+ co-doped bismuth-germanate system laser glass is a good ~2 μm laser gain glass material with good gain characteristics.