Optimization by energy transfer of the 2.7 μm emission in the Er:SrLaGa3O7 melilite crystal

Abstract A laser emission in the 3 μm range may find various interesting applications, for instance, in surgery, spectroscopy and LIDAR. This paper reports the spectroscopic study of the 4 I 11 2 → 4 I 13 2 transition of Er 3+ ions which occurs at ~ 2.7 μm in SrLaGa 3 O 7 (SLG). The emission cross section calculated at the maximum of the band is 0.65 × 10 −20 cm 2 . The lifetime of the 4 I 11 2 emitting level is quite long, due to a low active phonon energy (560 cm −1 ). The 2.7 μm emission corresponds to a self-terminating transition since τ( 4 I 13 2 ) > τ) 4 I 11 2 ) (5.8 ms and 780 μs, respectively). In this paper, the influence of various parameters is analysed to determine how to increase the population inversion by depopulating the 4 I 13 2 terminal level. Codopant ions presenting energy levels in good resonance with the Er 3+ 4 I 13 2 one can be used. Three codopants (Eu 3+ , Nd 3+ , Pr 3+ ) were investigated but only Pr 3+ decreases drastically the 4 I 13 2 level lifetime without significantly affecting the 4 I 11 2 one, leading to a good potentiality to achieve the 4 I 11 2 4 I 13 2 population inversion.