Dy^(3+):Y_(3)Al_(5)O_(12)晶体的光谱与黄色激光性能

Spectroscopic and Yellow Laser Features of Dy^(3+):Y_(3)Al_(5)O_(12)Single Crystals

近年来,黄色激光晶体在激光显示、激光医疗、激光雷达(光探测和测距)、玻色-爱因斯坦凝聚、原子冷却和俘获等领域具有广泛的应用,吸引了研究人员极大的兴趣。随着蓝光LD泵浦源的商用化,直接泵浦Dy^(3+)掺杂激光晶体可输出黄色激光,对应^(4)F_(9/2)→^(6)H_(13/2)跃迁。本工作采用提拉法生长了Dy^(3+)掺杂浓度分别为0.5%、1.0%、2.0%、3.0%和4.0%(原子分数)的Dy^(3+):Y_(3)Al_(5)O_(12)(Dy:YAG)晶体,并分析了晶体开裂的原因。基于Judd-Ofelt理论计算了J-O强度参数,并利用其评估了不同掺杂浓度的Dy:YAG晶体的其它激光参数。综合讨论了Dy^(3+)掺杂浓度对荧光分支比、受激发射截面、量子效率等光谱性能的影响。在五个晶体样品中,1.0%Dy:YAG晶体在447 nm激发下实现了582 nm最大的受激发射截面值和最强的荧光强度值,荧光寿命较长,达到0.823 ms。与之相比,2.0%Dy:YAG晶体发射参数值略低,但是其吸收系数更大。研究结果表明,激光二极管泵浦的Dy:YAG黄色激光晶体中Dy^(3+)离子的浓度为1.0%和2.0%较为合适,并基于2.0%Dy:YAG晶体实现了连续黄色激光输出,最大功率为166.8μW,激光峰值波长为582.5 nm。

In recent years,yellow laser crystals have raised great attentions owing to their comprehensive applications in the fields such as laser display,laser medical treatment,light detection and ranging(LIDAR),Bose-Einstein condensates,and atomic cooling and trapping.With the development of commercial blue light LD,the direct pumping of Dy^(3+)doped laser crystals has realized yellow laser based on its transition ^(4)F_(9/2)→^(6)H_(13/2).In this work,Dy^(3+):Y_(3)Al_(5)O_(12)(Dy:YAG)crystals with 0.5%,1.0%,2.0%,3.0%,and 4.0%(atomic fraction)nominal concentration of Dy^(3+)were grown using Czochralski method,the reason of crystal crack was discussed.Based on Judd-Ofelt(J-O)theory,the J-O intensity parameters and utilization,and other laser parameters of Dy:YAG crystals with different doping concentrations were evaluated.The effect of the doping concentration of Dy^(3+)on the spectroscopic performances like fluorescence branching ratio,stimulated emission cross-section,quantum efficiency,were analyzed comprehensively.Among all the five crystals,1.0%Dy:YAG has the largest stimulated emission cross-section for 582 nm yellow emission,an intense fluorescence intensity with the 447 nm excitation,and a longer decay time of 0.823 ms.The fluorescence intensity and stimulated emission cross-section of 2.0%Dy:YAG are slightly less than that of 1.0%Dy:YAG,but the former has a higher absorption coefficient.Hence,the spectroscopic analysis results show that 1.0%and 2.0%are the suitable concentrations of Dy^(3+)ion in YAG crystal for yellow laser operation by diode pumping.The continuous wave laser with peak at 582.5 nm and the maximum output power of 166.8μW yellow laser operation were realized in 2.0%Dy:YAG crystal.