Benefit of Pr3+ ions to the spectral properties of Er3+/Pr3+:SrLaAlO4 crystal for use in 2.7 μm mid-infrared laser

High optical quality Er3+ single doped and Er3+/Pr3+ co-doped SrLaAlO4 crystals were grown by the Czochralski method. Detailed spectroscopic analyses of Er3+:SrLaAlO4 and Er3+/Pr3+:SrLaAlO4 crystals were carried out. With the presence of Pr3+, the intensities of the red up-conversion and near-infrared emissions reduce to 1/4 and 1/10, while the intensity of mid-infrared emission increases to 1.6 times of those for Er3+:SrLaAlO4. Furthermore, the lifetimes of 4I11/2 upper and 4I13/2 lower laser levels for 2.7 μm emission fall from 1.06 ms to 4.42 ms–0.73 ms and 0.93 ms. It means that the self-termination bottleneck in Er3+ 2.7 μm laser was inhibited in a great degree. Deactivation effect of Pr3+ ions as well as the energy transfer mechanism in Er3+/Pr3+:SrLaAlO4 crystal are discussed in detail. The results indicate that the introduce of deactivation ion Pr3+ can be beneficial for achieving an enhanced 2.7 μm emission in Er3+/Pr3+:SrLaAlO4.