Near and mid-IR spectroscopic properties of Er~(3+) doped and Er~(3+)/Nd~(3+) codoped lutetium lithium fluoride single crystal

摘要

High quality Er~(3+)/Nd~(3+)co-doped Lutetium lithium fluoride (LiLuF4) single crystals with a size of Φ10 mm × 90 mm were grown by a Bridgman method. XRD, absorption spectra, and fluorescence spectra of these single crystals were studied. Enhanced mid-IR emission of 2.7 μm, and weakened up-conversion emission of 550 nm and down-conversion emission of 1.5 μm emission were observed in Er~(3+)/Nd~(3+) co-doped LiLuF4 single crystals under an exciting light of 808 nm, as compared with Er~(3+) singly-doping. Meanwhile, Mid-IR emissions of 3.6 μm and 4.2 μm were also observed in Er~(3+)/Nd~(3+) co-doped LiLuF4 single crystals. Energy transfer efficiencies between Nd~(3+) and Er~(3+) ions were calculated and the decay curves of the 1.06 μm for Nd~(3+) emission and 1.5 μm for Er~(3+) emission were analyzed with a modified Inokuti-Hirayama model. The large energy transfer efficiency of 95.6% and excellent optical properties indicate that this Er~(3+)/Nd~(3+) co-doped LiLuF4 single crystal is a potential candidate for the applications in mid-IR laser.