Spectroscopic investigations of Pr3+/Er3+:CaYAlO4 crystal for 2.7 μm emission

In this paper, we report on the 2.7 μm mid-infrared emission performance under 974 nm excitation in Pr3+/Er3+ co-doped CaYAlO4 crystal. It is found that with the presence of Pr3+ ion, the green, red up-conversion and the near-infrared emission are almost quenched. Besides, the laser lower level 4I13/2 depopulated much faster than the upper level 4I11/2. That indicates the population inversion become easier and the self-saturation for the transition 4I11/2 → 4I13/2 of Er3+ ion become weaker than that in Er3+:CaYAlO4 crystal. The energy transfer mechanism and the energy transfer coefficients are calculated and discussed. All the results imply that Pr3+ codoping benefits to achieving 2.7 μm laser in Pr3+/Er3+:CaYAlO4 crystal.