Benefit of Pr^3+ ions to the spectral properties of Pr^3+/Er^3+:CaGdAlO_4crystal for a 27 μm laser

Abstract

The spectra of Er3+:CaGdAlO4 and Pr3+/Er3+:CaGdAlO4 crystals were measured under the same conditions. With the presence of Pr3+ ions, the intensities of the green, red upconversion and near-infrared emissions are dramatically reduced to 1/20, 1/150, and 1/8.5 of those for Er3+:CaGdAlO4. Furthermore, the lifetimes of 4I11/2 upper and 4I13/2 lower laser levels fall from 450 and 982 μs to 84.8 and 74.3 μs. It is obvious that the self-saturation for Er3+ 2.7 μm laser is effectively suppressed. The energy transfer efficiencies and coefficients of Er3+→Pr3+ are also calculated. These results indicate that Pr3+ codoping is beneficial in achieving 2.7 μm laser in Pr3+/Er3+:CaGdAlO4 crystal.

Evaluation of spectroscopic properties of Er3+/Yb3+/Pr3+: SrGdGa3O7 crystal for use in mid-infrared lasers

“…where τ DA is the lifetime of Er 3+ in the existence of Pr 3+ , and τ A is the lifetime of Er 3+ in the absence of Pr 3+ 4. The calculated energy transfer efficiencies of Er 3+ : 4 I 11/2  → Pr 3+ : 1 G 4 and Er 3+ : 4 I 13/2  → Pr 3+ : 3 F 4 are about 29.0% and 90.6%, respectively.…”

“…To be more specific, the lifetime of 4 I 11/2 level is reduced to 1/1.4 while the lifetime of 4 I 13/2 level is reduced to 1/10.6 as compared with that in Er 3+ : SrGdGa 3 O 7 crystal. Based on the fluorescence lifetimes, the energy transfer efficiency from Er 3+ to Pr 3+ in Er 3+ /Yb 3+ /Pr 3+ : SrGdGa 3 O 7 crystal can be obtained from the following equation458:…”

“…Previous researches have shown that increasing Er 3+ concentration or co-doping with proper sensitive ions (such as Pr 3+ , Ho 3+ , Tm 3+ , etc .) can inhibit the self-termination bottleneck45678910. However, high doping concentration of Er 3+ may lead to poor quality of crystal.…”

“…Among the various matrix materials of mid-infrared solid-state lasers, fluoride, aluminate and gallate crystals are excellent for their low phonon energy, high thermal stability, stable chemical durability and so on451617. The spectroscopic properties and laser operations of Er 3+ doped CaF 2 , LiYF 4 , Y 3 Al 5 O 12 , CaYAlO 4 , CaGdAlO 4 , YSGG, GSGG and GGG crystals have been reported451718192021.…”

“…The spectroscopic properties and laser operations of Er 3+ doped CaF 2 , LiYF 4 , Y 3 Al 5 O 12 , CaYAlO 4 , CaGdAlO 4 , YSGG, GSGG and GGG crystals have been reported451718192021. In this work, SrGdGa 3 O 7 single crystal was chosen as the host matrix because it has lower melting point (about 1600 °C)22 as compared with the above aluminate and gallate crystals, and, large-sized crystals with high optical quality can be obtained more easily by using Czochralski technique.…”