Measurements of the spectroscopic and energy transfer parameters for Er³⁺-doped and Er³⁺, Pr³⁺-codoped PbO-Bi ₂O₃-Ga₂O₃ glasses

Measurements of the absorption and emission spectra and the characteristics of the luminescent decay of the ⁴I_11/2 and ⁴I_13/2 energy levels of Er³⁺ are presented for Er³⁺ singly doped and Er³⁺, Pr³⁺-codoped PbO-Bi₂O₃-Ga₂O₃ (PBG) glasses. The absorption cross sections were determined after accurate measurement both of glass component concentrations by use of electron probe analysis and of glass density. The characteristics of the luminescent decays were determined after direct pumping of the ⁴I_11/2 and ⁴I _13/2 energy levels of singly doped Er³⁺ PBG glass with a tunable pulsed optical parametric oscillator for calculation of the macroscopic rate parameters (W_ETU) for energy transfer upconversion (ETU) for these energy levels. The values for W_ETU relevant to the ⁴I_11/2 energy level were measured to be greater than the W_ETU values relevant to the ⁴I_13/2 energy level within the range of Er³⁺ concentrations studied. The macroscopic rate parameter (W_Er-Pr) for energy transfer to the Pr³⁺ deactivator ion from the ⁴I_13/2 energy level was also determined for a range of Pr³⁺ concentrations and for two fixed Er³⁺ concentrations. From a measurement of the energy-level lifetimes it was established that the rate of energy transfer from the ⁴I_13/2 energy level to Pr³⁺ is greater than the corresponding rate of energy transfer from the ⁴I _11/2 level to both the Pr³⁺ ion and the OH impurity. The overall results suggest that, to maximize the population inversion on the ⁴I_11/22→⁴I_13/2∼3 μm transition, deactivation of the ⁴I_13/2 level by way of small amounts of Pr³⁺ will be effective.