采用高温固相法, 以50Nb2O5-40Y2O3-2Nd2O3-8Yb2O3的量比在1 300 ℃下制备Nd3+/Yb3+掺杂YNbO4粉末样品。运用Judd-Ofelt理论研究样品光谱特性。由吸收谱中各吸收峰面积计算得到谱线强度参数Ωλ (λ=2, 4, 6), 进而得出理论振子强度及实验振子强度, 二者均方根偏差δrms=1.618×10-7。计算了Nd3+能级4F3/2→4IJ′(J′=15/2, 13/2, 11/2, 9/2)跃迁几率、跃迁分支比和能级寿命。4F3/2→4I11/2跃迁分支比最高(56.91%), 对应波长1 062 nm。且亚稳态4F3/2能级寿命较长, 为1.435 2 ms, 适合作为上转换中间能级。在980 nm 半导体激光器激发下, 观测到波长为487, 541, 662 nm上转换发光, 分别对应于Nd3+的2G9/2→4I9/2、4G7/2→4I9/2 和 4G7/2→4I13/2辐射跃迁。通过样品上转换发射功率与激光器工作电流进行的曲线拟合, 得到吸收光子数目依次为2.06, 1.99, 2.15, 确定3个发射峰均对应于双光子吸收。

Nd3+/Yb3+ doped YNbO4 powder sample was prepared with the molar ratios of 50Nb2O5-40Y2O3-2Nd2O3-8Yb2O3 by the high temperature solid state method at 1 300 ℃. The spectrum property was studied by using Judd-Ofelt theory. The spectral strength parameters Ωλ (λ=2, 4, 6) were computed based on the absorption peaks area of the absorption spectrum. The theoretical oscillator strength and the experimental oscillator strength were calculated according to the spectrum strength parameters, and the root mean square deviation (δrms) of them was 1.618×10-7. The parameters such as transition probability, decay branching ratios and level lifetime of Nd3+ transition 4F3/2→4IJ′(J′=15/2, 13/2, 11/2, 9/2) were obtained. The decay branching ratio of 4F3/2→4I11/2 (corresponding to the wavelength of 1 062 nm) is the most of 56.91%. The lifetime of metastable level 4F3/2 is longer of 1.435 2 ms, which is suitable for up-conversion intermediate level. Under the excitation of 980 nm diode laser, the up-conversion luminescence is observed at the wavelength of 487, 541 and 662 nm, corresponding to the radiative transitions of Nd3+:2G9/2→4I9/2, 4G7/2→4I9/2 and 4G7/2→4I13/2, respectively. The two-photon absorption of three emission peaks is determined by the fitting curve graph of sample up-conversion emission power and the laser working current when the absorption of the photon number in turn is 2.06, 1.99 and 2.15.