Evaluation of Mn 5+-doped Sr_5(VO_4)_3 F as a laser material based on excited-state absorption and stimulated-emission measurements

Excited-state absorption and stimulated-emission measurements of Mn5+-doped Sr5(VO4)3F were made with a pump-and-probe technique. Strong excited-state absorption bands were observed, corresponding to the transitions from the 1E(1D) metastable level to higher-lying singlet levels. The stimulated emission from the 1E(1D) level to the 3A2(3F) ground state is overlapped by a tail of the 1E(1D)→ 1T2(1D) excited-state absorption band. The cross section of the 1E(1D)→ 1T2(1D) transition at 1161 nm is (1.4±0.3)×10-20cm2 for E‖c and (2.4±0.5)×10-20cm2 for E⊥c. The ratio between the excited-state absorption and the stimulated-emission cross section at 1161 nm is 0.52 for E‖c and 1.82 for E⊥c. Therefore laser emission is expected to be inefficient in E‖c polarization and not to be possible in E⊥c polarization. The crystal field parameters in the cubic field approximation were determined to be Dq=1134cm-1, B=356 cm-1, and C=2918 cm-1, giving Dq/B=3.19 and C/B=8.20.