Abstract: The bulk single crystal of Nd 3+doped α~NaYF4 was in a molar ratio of starting material NaF:KF:YF3:NdF3 =30:18:47:5 grown by an improved flux-Bridgman method using KF as flux .XRD pattern shows that the incorporation of a small amount of Nd 3+ ions did not change the cubic phase structure of the single crystal .The actual doping concentration of Nd 3+ ions in the single crystal was determined to be 3.15mol;, which was smaller than the incorporation concentration .The results show that rare earth ions have segregation phenomenon in the crystal .According to the absorption spectrum , it can be seen that the strongest absorption peak at 800 nm.The maximum absorption coefficient αand the maximum absorption cross section σabs are respectively 0.91 cm -1 and 0.138 ×10 -20 cm2 .The emission spectrum has three peaks ranging from 800 nm to 1500 nm under 800 nm excitation .The strongest peak at 1052 nm produced by the 4 F3/2 level to the 4 I11/2 level transition .The fluorescence lifetime was measured to be 35 μs.The optical properties of Nd 3+doped NaYF4 crystal show that it has potential applications in the field of mid infrared laser .

Key words: The bulk single crystal of Nd 3+doped α~NaYF4 was in a molar ratio of starting material NaF:KF:YF3:NdF3 =30:18:47:5 grown by an improved flux-Bridgman method using KF as flux .XRD pattern shows that the incorporation of a small amount of Nd 3+ ions did not change the cubic phase structure of the single crystal .The actual doping concentration of Nd 3+ ions in the single crystal was determined to be 3.15mol;, which was smaller than the incorporation concentration .The results show that rare earth ions have segregation phenomenon in the crystal .According to the absorption spectrum , it can be seen that the strongest absorption peak at 800 nm.The maximum absorption coefficient αand the maximum absorption cross section σabs are respectively 0.91 cm -1 and 0.138 ×10 -20 cm2 .The emission spectrum has three peaks ranging from 800 nm to 1500 nm under 800 nm excitation .The strongest peak at 1052 nm produced by the 4 F3/2 level to the 4 I11/2 level transition .The fluorescence lifetime was measured to be 35 μs.The optical properties of Nd 3+doped NaYF4 crystal show that it has potential applications in the field of mid infrared laser .