OPTIMIZATION BY ENERGY-TRANSFER OF THE 2.7-MU-M EMISSION IN THE ER-SRLAGA3O7 MELILITE CRYSTAL

A laser emission in the 3 mu m range may find various interesting appl ications, for instance, in surgery, spectroscopy and LIDAR. This paper reports the spectroscopic study of the I-4(11/2) --> 4(13/2) transiti on of Er3+ ions which occurs at similar to 2.7 mu m in SrLaGa3O7 (SLG) . The emission cross section calculated at the maximum of the band is 0.65 x 10(-20) cm(2) The lifetime of the I-4(11/2) emitting level is q uite long, due to a low active phonon energy (560 cm(-1)). The 2.7 mu m emission corresponds to a self-terminating transition since tau(I-4( 13/2)) > tau(I-4(11/2)) (5.8 ms and 780 mu s, respectively). In this p aper, the influence of various parameters is analysed to determine how to increase the population inversion by depopulating the I-4(13/2) te rminal level. Codopant ions presenting energy levels in good resonance with the Er3+ 4I13/2 one can be used. Three codopants (Eu3+, Nd3+ Pr3 +) were investigated but only Pr3+ decreases drastically the I-4(13/2) level lifetime without significantly affecting the I-4(11/2) one, lea ding to a good potentiality to achieve the I-4(11/2)/4I(13/2) populati on inversion.