Gain properties of germanate glasses singly doped with Tm 3+ and Ho 3+ ions

Abstract

Two kinds of germanate glasses singly doped with the ion concentration of 2.0mol.%Tm 3+ and 2.0mol.%Ho 3+, respectively, were prepared. According to McCumber theory, the absorption and stimulated emission cross-sections corresponding to the 3H 6↔ 3F 4 transitions of Tm 3+ (at 1.8 µm) and the 5I 8↔ 5I 7 transitions of Ho 3+ (at 2.0 µm) were obtained, and respective gain cross-section spectra were also computed as a function of population inversion according to absorption and emission cross-sections and the ion concentrations. For Tm 3+-doped germanate glasses, the maximum of the absorption, emission, and gain cross-sections reached a value higher than those reported for fluorozirconate, fluoride, and oxyfluoride glasses. For Ho 3+-doped germanate glasses, the maximum of absorption, emission, and gain cross-sections reached a value higher than that reported for fluorozircoaluminate glasses. Hence, these Tm 3+-doped and Ho 3+-doped germanate glasses exhibited an advantage for application in mid-infrared lasers at about 1.8 and 2.0 µm wavelength.