采用坩埚下降法在非真空密闭条件下生长出尺寸为φ9mm×68mm的1mol%Er3+:LiYF4单晶材料,测试了样品的折射率、透过光谱、吸收光谱、以及在980nm和792nm激光泵浦下的近红外和中红外荧光光谱.应用Judd-Ofelt理论计算了Er3+离子在LiYF4晶体材料中的强度参数(Ωt,t=2,4,6)、能级跃迁振子强度(fcal)、自发辐射跃迁几率(A)、荧光分支比(β)、辐射寿命(τrad)等光谱参数,讨论了其近红外和中红外的荧光特性.结果表明,在980nm和792nm激光泵浦下观察到了1.5μm近红外荧光和3.0μm中红外荧光,分别对应于Er3+:4I13/2→4I15/2和4I11/2→4I13/2跃迁,并分析了3.0μm中红外荧光强度较弱的可能原因.
Er3+:LiYF4 single crystal was grown by the Bridgman method under non-vacuum atmosphere.The single crystal was in size of φ9mm×68mm with 1mol% concentration of Er3+ ions.Optical properties of the single crystal in-cluding the refractive index,UV and IR transmission spectra,absorption spectrum,near-infrared emission spectrum under 980nm excitation and mid-infrared emission spectrum under 792nm excitation were measured.The intensity parameters(Ωt,t=2,4,6),oscillator strength(fcal),transition probabilities(A),branching ratios(β) and radiation lifetimes(τrad) of Er3+ ions in the LiYF4 were estimated by using the Judd-Ofelt theory.The near-and mid-infrared fluorescence properties of the sample were discussed.The results indicate that near infrared fluorescence at 1.5μm corresponding to the Er3+:4I13/2→4I15/2 transition is observed under 980nm excitation while mid-infrared fluorescence at 3.0μm corre-sponding to the Er3+:4I11/2→4I13/2 transition is detected under 792 nm excitation.The reason that caused the weakening of fluorescence at 3.0μm is analyzed.