Populations and Emission Properties of the 5 I 6 and 5 I 7 Levels in Ho 3+ Doped into PbO–Bi 2 O 3 –Ga 2 O 3 Glasses

Emission properties of PbO–Bi 2 O 3 –Ga 2 O 3 glasses doped with Ho 3+ were investigated for fiber‐optic amplification at the 1.18 μm wavelength region. When the glasses were doped with Ho 3+ ions only, there was a weak emission at 1.18 μm with a lifetime of ∼200 μs. However, when Yb 3+ ions were codoped, the lifetime of the 1.18 μm emission increased to 630 μs together with a significant increase in intensity. A similar enhancement in the intensity and lifetimes was realized for the 2.05 μm emission. These effects are due to energy transfer from the Yb 3+ : 2 F 5/2 to the Ho 3+ : 5 I 6 level. Devitrification of the ternary PbO–Bi 2 O 3 –Ga 2 O 3 glasses was efficiently suppressed by adding 10 mol% GeO 2 . Optimum Ho 3+ concentration was ∼0.4 mol%, whereas Yb 3+ ions can be added up to the solubility limit.