Wang Lili, Liu Zhenyu, Chen Zhe, Zhao Dan, Qin Guanshi, Qin Weiping
Opt Express. 2011 Dec 5;19(25):25471-8. doi: 10.1364/OE.19.025471.
Under 980 nm excitation, multiple ultraviolet and visible upconversion luminescence from Ho3+ and Eu3+ ions were observed in Yb3+/Ho3+/Eu3+ tri-doped NaYF4 microcrystals (MCs). The high-energy states (5H3-7, 5L6, 5D3 and 5D2) of Eu3+ ions could be efficiently populated by two-step energy transfer (ET) processes of Yb → Ho → Eu. Four-, three-, two-photon UC processes of Eu3+ ions were confirmed by the dependence of 5H3-7, 5L6 and 5D0 levels emission intensities on the pumping power.
在980 nm激发下，在Yb3+/Ho3+/Eu3+三掺杂的NaYF4微晶（MCs）中观察到了来自Ho3+和Eu3+离子的多种紫外和可见上转换发光。Eu3+离子的高能态（5H3 - 7、5L6、5D3和5D2）可通过Yb→Ho→Eu的两步能量转移（ET）过程有效地填充。通过5H3 - 7、5L6和5D0能级发射强度对泵浦功率的依赖性，证实了Eu3+离子的四光子、三光子、双光子上转换过程。
