Luminescence properties of Er3+/Nd3+ co-doped Na5Lu9F32 single crystals for 2.7 μm mid-infrared laser

Abstract

The enhanced 2.7 μm mid-infrared emission from the Er3+:4I11/2 → 4I13/2 transition with Nd3+ ions as the sensitizer was achieved in the Na5Lu9F32 single crystal which was successfully grown by a Bridgman method. The transmission spectrum was tested and almost no absorption of 2.7 μm band was observed. It was indicated that the content of OH- ion was very low in the crystal and it was beneficial to the 2.7 μm mid-infrared laser output. Intense 2.7 μm emissions were achieved with Nd3+ ions sensitizing Er3+ ions under the 800 nm LD pumping and the energy transfer processes between Er3+ and Nd3+ ions were analyzed. Meanwhile, the greatly decreased near infrared emission at 1.5 μm and green up-conversion emission were obtained. Additionally, the optimized concentration ratio of Er3+ to Nd3+ for efficient 2.7 μm emission was investigated in this work and the maximum emission cross section at 2.7 μm was calculated. The decay curve of 1.5 μm emission could be well fitted by Inokuti-Hirayama expression, which was strongly indicated the dipole-dipole energy transfer from Er3+ to Nd3+ ions. The results showed that Er3+/Nd3+ co-doped Na5Lu9F32 single crystal had potential applications in 2.7 μm mid-infrared laser.