基于能量传递机制加强的Ho,Yb双掺氟化物晶体的激光制冷研究

Laser cooling of solids is founded on the anti-Stocks luminescence process, and it is currently the only one all-solid-state cryogenic cooling technique. Featured with advantages of compactness, no vibration, no electromagnetic interference and so on, it can be utilized in local refrigeration of space-based detectors. To study laser cooling of solids is significant for construction of national defense and informatization. Limited by non-radiative heating at room temperatures and weakened resonant absorption at cryogenic temperatures, the traditional laser cooling of solids encounters problems of low cooling efficiency, long cooling time and so on. How to promote the cooling performance has became the key and difficult issue of this field. This work study enhanced laser cooling in Ho-Yb co-doped fluoride crystals based on energy transfer mechanism, and intends to improve the performance of solid-state laser cooling from the mechanism perspective via energy transfer and pulsed excitation.The main research contents as follows: (1)We first develop the density matrix model for pulsed laser cooling in Ho, Yb co-doped fluoride crystals, study the radiation and cooling properties of the system under influence of the Ho-Yb energy transfer mechanism, and explore the conditions needed for cooling enhancement. (2)We experimentally study pulsed laser cooling in Ho, Yb co-doped fluoride crystals, and reveal the cooperated microscopic mechanism of energy transfer and pulsed excitation on the enhancement of anti-Stokes fluorescence and cooling effect.

固体激光制冷基于反斯托克斯荧光辐射过程，是目前仅有的一种全固态超低温制冷技术，具有紧凑、无振动及无电磁干扰等优点，可用于航天搭载探测器的局部制冷。开展固体激光制冷研究对国防及信息化建设有重要的意义。受非辐射产热（室温附近）及弱共振吸收（超低温区域）两方面的限制，传统固体激光制冷存在制冷效率低，制冷时间长等问题。如何提高制冷性能已成为该项研究的关键及难点问题。本项目开展基于能量传递加强的Ho,Yb双掺氟化物晶体的激光制冷研究，旨在利用能量传递和脉冲激发从机理上改进固体激光制冷表现。主要研究内容包括：(1)率先发展基于Ho,Yb双掺氟化物晶体的脉冲激光制冷密度矩阵模型，研究在Ho-Yb能量传递机制作用下系统的辐射及制冷特性，探索出实现激光制冷增强的条件。(2)实验研究Ho,Yb双掺氟化物晶体的脉冲激光制冷，揭示能量传递和脉冲激发增强反斯托克斯荧光及制冷效果的微观协同作用机理。

固体激光制冷基于反斯托克斯荧光辐射过程，是目前仅有的一种全固态超低温制冷技术，具有紧凑、无振动及无电磁干扰等优点，可用于航天搭载探测器的局部制冷。开展固体激光制冷研究对国防及信息化建设有重要的意义。受非辐射产热（室温附近）及弱共振吸收（超低温区域）两方面的限制，传统固体激光制冷存在制冷效率低，制冷时间长等问题。如何提高制冷性能已成为该项研究的关键及难点问题。本项目开展基于能量传递加强的Ho,Yb双掺氟化物晶体的激光制冷研究，旨在利用能量传递和脉冲激发从机理上改进固体激光制冷表现。主要研究内容包括：(1)率先发展兼容激光诱导热调制光谱方法的多能级光学制冷普适模型。基于跃迁分支分析引入量子产出频率（QYF）的概念, 对光学制冷中常见的跃迁通道做热力学分析。(2) 基于能量传递理论和脉冲激光制冷密度矩阵模型，研究在Ho-Yb能量传递机制和脉冲抽运作用下系统的辐射及制冷特性，探索出实现激光制冷增强的条件，揭示能量传递和脉冲激发增强反斯托克斯荧光及制冷效果的微观作用机理。