LAUSR

Abstract This paper reported on successful preparation of Na 5 Lu 9 F 32 single crystals co-doped with ∼2 mol% Er 3+ and various Tm 3+ concentrations from 0.7 mol% to 3.2 mol% by Bridgman method. The J-O intensity parameters of Er 3+ were calculated and analyzed according to the absorption spectra. The fluorescence decay curve at Er 3+ : 4 I 13/2 level was measured to investigate the luminescent properties of the Er 3+ /Tm 3+ co-doped Na 5 Lu 9 F 32 , and the energy transfer process between Er 3+ and Tm 3+ . An intense 2.7 μm emission was achieved with Tm 3+ ions sensitizing Er 3+ ions under the 800 nm LD pumping. The maximum emission intensity at 2.7 μm was obtained at about 3.2 mol% doping concentration of Tm 3+ when the concentration of Er 3+ ions was fixed at ∼2 mol% in the current research. The calculated maximum value of emission cross section at 2.7 μm was 2.22 × 10 −20  cm 2 , and energy transfer efficiency from Er 3+ : 4 I 13/2 to Tm 3+ : 3 F 4 was 78%. The electric dipole-dipole interaction was dominant for the energy transfer from Er 3+ to Tm 3+ ions by using Inokuti-Hirayama’s model.