Nd∶GdYAG激光晶体的光谱分析及热学性能研究

Spectral Analysis and Thermal Properties of Nd∶GdYAG Laser Crystal

本文对所生长的Nd∶GdYAG晶体的吸收光谱和荧光光谱进行了测试,采用Judd-Ofelt理论对振子强度和线强、强度参数Ω_(t)、4 F_(3/2)→4 I_(J)能级间的跃迁概率、能级辐射寿命、荧光分支比等光谱参数进行了计算,相关数据与YAG、LuAG、YVO4等晶体进行了对比。Ωt计算得出Ω2=(0.813±0.200)×10^(-20)cm^(2),Ω4=(3.381±0.187)×10^(-20)cm^(2),Ω6=(5.135±0.278)×10^(-20)cm^(2),相比YAG、LuAG、YVO4等晶体,Nd∶GdYAG晶体的强度参数Ω2较大,表明Gd^(3+)的掺入增大了基质的无序度。计算并拟合了300~1200 nm的吸收截面和折射率,其中808 nm处的吸收截面为5.0×10^(-20)cm^(2),1064 nm处的折射率为1.80。实测4 F3/2能级的荧光寿命为228μs,与计算的能级辐射寿命240μs接近;1064 nm处的发射截面为1.23×10^(-19)cm^(2),接近Nd∶YAG晶体的发射截面。室温下Nd∶GdYAG晶体的热导率为5.992 W/(m·K),略小于Nd∶YAG和Nd∶GGG,但大于Nd∶YVO4晶体。研究表明,Nd∶GdYAG是一种有应用前景的新型激光晶体材料。

The adsorption and fluorescence spectra of the grown Nd∶GdYAG were measured.The spectral parameters,such as oscillator strength,line strength,intensity parameterΩt,transition probability between 4 F_(3/2)→4 I_(J)levels,radiation lifetime,and fluorescence branching ratio,were calculated with Judd-Ofelt theory.The calculatedΩt areΩ_(2)=(0.813±0.200)×10-20 cm2,Ω4=(3.381±0.187)×10-20 cm2,Ω6=(5.135±0.278)×10^(-20)cm^(2),respectively.Compared with Nd-doped YAG,LuAG,YVO4,and other crystals,Nd∶GdYAG crystal has a largerΩ_(2),showing that the addition of Gd^(3+)increases the disorder of the host.The absorption cross-section and refractive index in the range of 300~1200 nm were calculated and fitted.The absorption cross-section at 808 nm is 5.0×10^(-20)cm^(2).The refractive index at 1064 nm is 1.80.The measured fluorescence lifetime of 4 F3/2 level is 228μs,which is close to the calculated radiation lifetime of 240μs.The emission cross-section at 1064 nm is 1.23×10^(-19)cm^(2),which is close to that of Nd∶YAG crystal.Addition,at room temperature,the thermal conductivity of Nd∶GdYAG crystal is 5.992 W/(m·K),which is slightly smaller than that of Nd∶YAG and Nd∶GGG,but larger than that of Nd∶YVO_(4)crystal.The results show that Nd∶GdYAG is a promising new laser crystal material.