Erbium-doped potassium bismuth gallate glasses

We demonstrate potassium bismuth gallate glasses as suitable hosts for rare-earth-ion erbium (Er³⁺) operating in the 1.55-μm-wavelength region. The absorption and luminescence spectra along with the luminescence decay time were measured. The emission peak of the ⁴I_13/2 → ⁴I_15/2 transition is at the 1.53-μm wavelength, and the spectral bandwidth is 85 nm, which is one of the broadest. The lifetime of the ⁴I_13/2 level is ∼2.42 ms, and the quantum efficiency is ∼100%. The emission cross section is estimated to be ∼12. 4 × 10^-21 cm², which is one of the highest among different oxide glasses. The gain coefficient is also calculated, and our results show that potassium bismuth gallate glasses are excellent host materials for broadband-amplifier and high-power-laser applications.