中文摘要：

用980 nm的近红外激光泵浦Bridgman方法生长的Tb~（3＋）/Yb~（3＋）共掺的α-NaYF4单晶,研究了其上转换荧光以及荧光强度与泵浦功率的关系。结果表明：2个或者3个激发态的Yb~（3＋）离子传递能量给1个Tb~（3＋）离子并引发了双光子或三光子上转换。高效的三光子上转换的381、414、435和462 nm光和双光子上转换的481、541、587、651、659和668 nm光分别产生于Tb~（3＋）离子的~5D3→~7FJ（J=6,5,4,3）和~5D4→~7FJ（J=6,5,4,3,2,1）辐射跃迁。现有实验下,当Tb~（3＋）的掺杂量为0.52%（摩尔分数）时,Yb~（3＋）的最佳掺杂量为7.98%,并可以进一步增加。以上结果表明了Tb~（3＋）/Yb~（3＋）共掺的α-NaYF4单晶在上转换绿光固体激光材料方面的潜在应用。

英文摘要：

The up-conversion （UC） luminescence and the pump power dependence on the UC emissions of the Tb3＋/Yb3＋ co-doped ct-NaYF4 single crystals grown by the Bridgman method under the excitation of near-infrared light at 980 nm were investigated. The results show that three or two excited Yb3＋ ions transferring the energy to a Tb3＋ ion can lead to the three- or two-photon UC process. The efficient three- photon UC emission at 381,414, 435 and 462 nm and the two-photon UC emissions at 481,541,587, 651,659 and 668 nm occur due to the transitions 5D3→7FJ （J= 6, 5, 4 and 3） and 5D4→7FJ （3= 6, 5, 4, 3, 2 and 1） of Tb3＋, respectively. The ptimized Yb3＋ concentration is 7.98% （mole fraction） at Tb3＋ concentration of 0.52%. It is indicated that Wb3＋/yb3＋ doped α-NaYF4 single crystal is a promising candidate of the UC material applied for the green solid-state laser.