Tm3+掺杂锗碲酸盐玻璃的近2µm光谱性质∗

摘要

用高温熔融法制备了Tm2 O3掺杂浓度为0.25,0.5,0.75,1,1.25,1.5 mol%的40 GeO2-35TeO2-15PbO-5Al2O3-2.5CaO-2.5SrO锗碲酸盐玻璃.热学性质测试表明该玻璃的转变温度为446◦C,没有析晶峰.玻璃的最大声子能量约为750 cm−1.利用Judd-Ofelt理论计算了Tm3+的Judd-Ofelt参数Ωt(t =2,4,6)、不同浓度下Tm3+离子各激发态能级的自发辐射概率、荧光分支比以及辐射寿命等参数.采用808 nm波长抽运源测试了Tm3+离子的荧光光谱.发现掺杂浓度为1 mol%时约1.8µm处的荧光强度最强.根据McCumber理论计算了3F4→3H6的发射截面,其峰值发射截面为6.5×10−21 cm2.根据速率方程计算了玻璃中OH引起的Tm3+的3 F4能级的无辐射弛豫速率,随着Tm3+浓度增加, OH对3 F4能级的猝灭速率增加.这种玻璃有望研制成一种新型的约2µm的激光玻璃材料.%Tm2O3-doped 40GeO2-35TeO2-15PbO-5Al2O3-2.5CaO-2.5SrO glasses with different Tm3+ ion concentrations are fabricated by conventional melt-quenching method. From the measurements of thermal properties it follows that the glass transition temperature is 446 ◦C and crystallization peak does not exist. The maxmium phonon energy of the host is ∼ 750 cm−1. The Judd-Ofelt strength parameter Ωt (t = 2, 4, 6), the radiative transition probalities, the branching ratios and the radiative lifetime are calculated according to Judd-Ofelt theory. The emission spectra of Tm3+doped glasses with different Tm2O3 concentrations are measured under the excitation by an 808 nm diode laser. The result shows that the emission intensity at ∼ 1.8 µm reaches a maximal value when the Tm2O3-doping concentration is 1 mol% and then it decreases with the further increase of Tm2O3-doping concentration. The emission cross section of 3F4 → 3H6 is calculated based on the McCumber theory. The peak emission cross-section is 6.5 × 10−21 cm2. The non-radiative transition rate of 3F4 caused by OH is calculated quantitatively by rate equation. The results indicate that the germanate-tellurite glass is a new candidate for mid-infrared laser application.