Populations and emission properties of the I-5(6) and I-5(7) levels in Ho3+ doped into PbO-Bi2O3-Ga2O3 glasses

Abstract

Emission properties of PbO-Bi2O3-Ga2O3 glasses doped with Ho3+ were investigated for fiber-optic amplification at the 1.18 mu m wavelength region. When the glasses were doped with Ho3+ ions only, there was a weak emission at 1.18 mu m with a lifetime of similar to 200 mu s. However, when Yb3+ ions were codoped, the lifetime of the 1.18 mu m emission increased to 630 mu s together with a significant increase in intensity. A similar enhancement in the intensity and lifetimes was realized for the 2.05 mu m emission. These effects are due to energy transfer from the Yb3+:F-2(5/2) to the Ho3+:I-5(6) level. Devitrification of the ternary PbO-Bi2O3-Ga2O3 glasses was efficiently suppressed by adding 10 mol% GeO2. Optimum Ho3+ concentration was similar to 0.4 mol%, whereas Yb3+ ions can be added up to the solubility limit.