Two Er:CeF3 crystals doped with 1.0 and 1.2 wt.% Er2O3 and one pure Ce
F3 crystal were grown, their absorption and fluorescence spectra at ro
om temperature were measured. Compared with pure crystal, the emission
intensity of Ce3+ in Er : CeF3 decreased obviously, it is the sign of
energy transfer from 5d state of lattice Ce3+ to 4f state of Er3+ ion
s which improves the stimulation emission efficiency of Er3+ ions.