Abstract The 2.0 μm spectral characteristics of the 980 nm LD pumped Er3+/Ho3+/Yb3+ tri-doped Na5Y9F32 single crystals grown by an improved Bridgman method were investigated with the help of their absorption spectra, emission spectra and decay curves. The introduction of Yb3+ and Er3+ greatly improves the 2.0 fluorescence intensity through joint energy transfer processes from Yb3+ to Er3+, and Er3+ to Ho3+. The doping concentrations of 0.5 mol% Er3+ and 1.0 mol% Yb3+ ions were optimized to obtain the maximum 2.0 μm fluorescence intensities for the fixed 0.8 mol% Ho3+/1 mol% Yb3+ and 0.8 mol% Ho3+/0.5 mol% Er3+ doped Na5Y9F32 single crystals. Besides, according to the absorption and fluorescence spectra of the crystals, the absorption and emission cross-sections were calculated, and excellent gain performance was also obtained. Meanwhile, the maximum 2.0 μm emission lifetime of Er3+/Ho3+/Yb3+ tri-doped Na5Y9F32 single crystal can reach ~21.82 ms. The energy transfer mechanisms among the three rare-earth ions were further investigated by calculating energy transfer micro-parameters (CDA) and efficiencies. The excellent properties in both intense emission at 2.0 μm and chemical stability obtained in the Er3+/Ho3+/Yb3+ tri-doped Na5Y9F32 single crystals make them promising candidate material for 2.0 μm laser.

中文翻译：

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由 Er3+ 和 Yb3+ 双重敏化的 Ho3+ 掺杂 Na5Y9F32 单晶可实现 2.0 μm 的高效发射

摘要 利用吸收光谱、发射光谱和衰减曲线研究了采用改进布里奇曼法生长的980 nm LD泵浦Er3+/Ho3+/Yb3+三掺杂Na5Y9F32单晶的2.0 μm光谱特性。Yb3+ 和Er3+ 的引入通过Yb3+ 到Er3+ 和Er3+ 到Ho3+ 的联合能量转移过程大大提高了2.0 荧光强度。优化了 0.5 mol% Er3+ 和 1.0 mol% Yb3+ 离子的掺杂浓度，以获得固定的 0.8 mol% Ho3+/1 mol% Yb3+ 和 0.8 mol% Ho3+/0.5 mol% Er3+ 掺杂 Na5Y9F32 单晶的最大 2.0 μm 荧光强度. 此外，根据晶体的吸收和荧光光谱，计算了吸收和发射截面，也获得了优异的增益性能。同时，Er3+/Ho3+/Yb3+ 三掺杂 Na5Y9F32 单晶的最大 2.0 μm 发射寿命可达~21.82 ms。通过计算能量转移微参数（CDA）和效率，进一步研究了三种稀土离子之间的能量转移机制。Er3+/Ho3+/Yb3+ 三掺杂 Na5Y9F32 单晶在 2.0 μm 处的强发射和化学稳定性方面的优异性能使其成为 2.0 μm 激光的有希望的候选材料。