Tm^(3+)/Ho^(3+)共掺碲酸盐玻璃的2.0μm发光特性及能量传递

2.0 μm emission properties and energy transfer of Tm^(3+)/Ho^(3+)-codoped tellurite glass

研究了Tm3+/Ho3+共掺TeO2-WO3-ZnO玻璃在808nm激光二极管抽运下的2.0μm发光特性及Tm3+与Ho3+之间的能量传递.应用Judd-Ofelt理论计算了Ho3+在碲酸盐玻璃中的谱线强度参量Ωt(t=2,4,6)、自发辐射概率Ar、辐射寿命τr等.计算了Ho3+的吸收截面σa(λ)和受激发射截面σe(λ).结果表明:碲酸盐玻璃中Tm3+→Ho3+正向能量传递系数大约是Tm3+←Ho3+反向能量传递系数的18倍.Ho3+离子的5I7能级的寿命为3.9ms,2.0μm处的最大发射截面为9.15×10-21cm2.在0.5mol%Tm2O3和0.15mol%Ho2O3共掺的碲酸盐玻璃中能获得2.0μm的最大增益.通过比较氟化物、碲酸盐和镓铋酸盐重金属氧化物等玻璃中Ho3+的量子效率η,σe×τm值和增益系数G(λ)等,发现Tm3+/Ho3+共掺碲酸盐玻璃是一种理想的2.0μm激光器用基质玻璃.

This paper reports on spectroscopic properties and energy transfer of Tm^3 ＋/Ho^3 ＋ -codoped ZnO-WO3-TeO2 glass upon excitation of 808nm diode laser. The J-O strength parameters, spontaneous emission probability and radiative lifetime of Ho^3 ＋ were calculated using Judd-Ofeh theory. The absorption cross-section and stimulated emission cross-section were also investigated. Our result indicates that the highest gain of 2.0 ttm emission, which comes from 5I7 to 5I8 transition of Ho^3＋ , might be achieved from the glass at the rare-earth ion concentration of 0.5 mol% of Tm2O3 and 0.15 mol% of Ho2O3 . It is found that coefficients of the forward Tm^3＋ →Ho^3＋ energy transfer is about 18 times that for the backward Tm^3←Ho^3＋ energy transfer. The calculated fluorescence lifetime of the 5 I7 level of Ho^3 ＋ is 3.9 ms and the emission cross section of the 5 I7 →5I8 transition of Ho^3＋ exhibits a maximum of 9.15 x 10^-21 cm^2 at 2027 nm. We also found that Tm^3＋/Ho^3＋ -codoped tellurite glass is a promising host material for potential 2.0 μm laser by comparing the quantum efficiencies, the values of σe x τm and gain coefficients of fluoride and heavy metal oxide glasses respectively.