The precise characterisation of the ground state absorption cross section around 800 nm for Nd:YAG from room temperature to liquid nitrogen temperature is presented. These results enabled the measurement of the energy transfer upconversion macroparameter over the same temperature range for 0.3at.%- and 0.6at.%-doped samples via a simple automated z-scan technique. The main absorption cross section peak at 808 nm is found to increase from (6.90 ± 0.30) pm2 at the highest, to (42.30 ± 2.10) pm2 at the lowest temperatures. Over the same range, the energy transfer upconversion parameter increases from (21.5 ± 2.3) 10−18cm3/s to (52.6 ± 2.5) 10−18cm3/s and from (36.0 ± 2.8) 10−18cm3/s to (65.7 ± 1.9) 10−18cm3/s, for the 0.3at.%- and 0.6at.%-doped crystals, respectively. Although energy transfer upconversion is known to limit room temperature operation on the 946 nm transition for this laser, we demonstrate that when the crystal is cooled to liquid nitrogen temperature, despite a twofold increase in the macroparameter, it has a negligible effect on performance.

中文翻译：

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Nd:YAG 在低温下的能量转移上转换

介绍了 Nd:YAG 从室温到液氮温度在 800 nm 附近的基态吸收截面的精确表征。这些结果能够通过简单的自动 z 扫描技术在相同温度范围内测量 0.3at.% 和 0.6at.% 掺杂样品的能量转移上转换宏参数。发现 808 nm 处的主要吸收截面峰从最高的 (6.90 ± 0.30) pm2 增加到最低温度的 (42.30 ± 2.10) pm2。在相同范围内，能量转移上转换参数从 (21.5 ± 2.3) 10−18cm3/s 增加到 (52.6 ± 2.5) 10−18cm3/s 和从 (36.0 ± 2.8) 10−18cm3/s 增加到 (65.7 ± 1.9) ) 10−18cm3/s，分别用于 0.3at.% 和 0.6at.% 掺杂的晶体。