Observation of optical refrigeration in a holmium-doped crystal
Observation of optical refrigeration in a holmium-doped crystal
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DOI：
10.1364/prj.7.000445
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发表时间：
2018-11
影响因子：
7.6
通讯作者：
Saeid Rostami;A. Albrecht;A. Volpi;M. Sheik-Bahae
中科院分区：
文献类型：
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作者：
Saeid Rostami;A. Albrecht;A. Volpi;M. Sheik-Bahae
我们报告，尽我们所知，第一次演示固态光制冷的Ho掺杂材料。用中红外激光冷却掺1mol%Ho的氟化钇锂（YLF）晶体，研究了晶体的外量子效率和寄生背景吸收。使用详细的温度依赖的光谱分析，最低可实现的温度为1%的Ho：YLF样品的估计。由于其更窄的基态和激发态流形，更大的吸收截面，以及最佳冷却波长2070 nm的商业可用的高功率和高效率的Tm-光纤激光器的重合，Ho 3+掺杂的晶体是上级优于Tm 3+掺杂系统的中红外光学制冷。随着材料纯度的进一步提高和掺杂浓度的增加，它们在提高冷却效率方面具有很大的潜力，比目前最好的Yb：YLF系统提高近两倍，实现更低的温度，以及实现人眼安全的中红外高功率辐射平衡激光器。
We report, to the best of our knowledge, the first demonstration of solid-state optical refrigeration of a Ho-doped material. A 1 mol% Ho-doped yttrium lithium fluoride (YLF) crystal is cooled by mid-IR laser radiation, and its external quantum efficiency and parasitic background absorption are evaluated. Using detailed temperature-dependent spectroscopic analysis, the minimum achievable temperature of a 1% Ho:YLF sample is estimated. Owing to its narrower ground- and excited-state manifolds, larger absorption cross section, and the coincidence of the optimum cooling wavelength of 2070 nm with commercially available high-power and highly efficient Tm-fiber lasers, Ho3+-doped crystals are superior to Tm3+-doped systems for mid-IR optical refrigeration. With further improvement in material purity and increased doping concentration, they offer great potential towards enhancing the cooling efficiency nearly two-fold over the best current Yb:YLF systems, achieving lower temperatures as well as for the realization of eye-safe mid-IR high-power radiation balanced lasers.