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This paper reports the main spectroscopic characterizations and laser experiments carried out on two new crystal hosts: the! yttrium orthosilicate Y2SiO5 and the silicate oxyapatite Sr2Y8(SiO4)6O2 (hereafter noted SYS), doped with Ytterbium and Erbium for a 1,55 μm laser emission and with Thulium for a 2 μm emission. Four new lasers have been demonstrated at 1,554 μm, 1,576 μm, 1,99 μm and 2,05 μm for respectively Yb,Er:SYS; Yb,Er:Y2SiO5; Tm:SYS and Tm:Y2SiO5. If for the Yb,Er codoped materials laser performances are still poor compared with the Yb,Er phosphate glass, the Tm doped materials exhibit laser performances similar to the Tm:YAG and look very promising.

Photoluminescence (PL) of Molecular Beam Epitaxy grown Er doped Ga 0.55Al0.45As has been studied under continuous and pulsed laser excitation . The observed PL lines are attributed to transitions from the first excited stated 4I13/2 to the ground state 4I15/2 . The life time of the 4I13/2 level is found to be 1 ms at 10K, which is comparable to the decay time observed in insulators.Using two-beam experiments we show that there are losses (Auger effect) that occur during the PL excitation.We propose the following model for the Er PL excitation process: excitons bound to Er are created and decay non radiatively by energy transfer to the rare earth (which is the cause of the Er related PL) or to free carriers by Auger effect (which is the cause of the observed losses).