Ho:YLF晶体光学制冷的性能分析

Performance Analysis of Ho:YLF Crystal Optical Cooling

摘要: 固体激光制冷技术基于反斯托克斯荧光机制，可实现无振动、无电磁干扰的低温制冷，在精密光学仪器和深空探测等领域具有广阔应用前景。掺钬氟化锂钇(Ho:YLF)晶体因其在2 μm波段较大的吸收截面和较低的声子能量，被认为是实现中红外波段光学制冷的候选材料。然而，Ho³⁺离子丰富的4f能级结构引入了显著的能量传递上转换(ETU)效应，使得传统准二能级模型的预测精度受到限制。本文基于Ho³⁺的多能级速率方程，建立了包含ETU通道的光学制冷模型，对外量子效率进行了修正，分析了Ho:YLF的净制冷功率密度与制冷效率。

Abstract: Solid-state laser cooling technology is based on the anti-Stokes fluorescence mechanism to achieve low-temperature refrigeration without vibration and electromagnetic interference, and has broad application prospects in fields such as precision optical instruments and deep space exploration. Holmium-doped lithium yttrium fluoride (Ho:YLF) crystal is considered a candidate material for optical refrigeration in the mid-infrared band due to its large absorption cross section and low phonon energy in the 2 μm band. However, the abundant 4f level structure of Ho³⁺ ions introduces a significant energy transfer upconversion (ETU) effect, which limits the prediction accuracy of traditional quasi-two-level models. Based on the multi-level rate equation of Ho³⁺, this paper establishes an optical refrigeration model including ETU channels, corrects the external quantum efficiency, and analyzes the net refrigeration power density and refrigeration efficiency of Ho:YLF.