Yb^(3+):LuLiF_4晶体激光制冷的热负载管理

Thermal load management of laser cooling of Yb^(3+):LuLiF_4 crystal

为了研究Yb^(3+):LuLiF_4晶体在反Stokes荧光制冷过程中的热负载管理机制,开展了在常压(1.0×105Pa)和高真空(2.5×10-3 Pa)状态下的激光制冷实验。掺杂浓度为5 mol%的样品由两根光纤支撑,被放置在真空状态不同的腔体内。利用波长1 020 nm,功率3 W的激光激发样品。在常压下,样品温度相对室温下降了△T≈12 K;在高真空下,△T≈26 K。对于常压状态,空气热对流负载约11.23 m W,光纤热传导负载约0.03 m W,腔体热辐射负载约4.8 m W。对于高真空状态,空气热对流负载约0.03 m W,光纤热传导负载约0.07 m W,腔体热辐射负载约10.4 m W。实验结果表明,当腔体压强由-105 Pa降至-10-3Pa时,空气热对流负载几乎忽略不计,而腔体热辐射负载则成为作用在制冷样品上最主要的热负载。

In order to study the thermal load management mechanism of Yb3+:LuLiF4crystal in anti-Stokes fluorescence process,laser cooling experiment based on standard pressure(1.0×10^5Pa)and high vacuum(2.5×10^-3Pa)states were carried out.The5mol%doped sample was supported by two optical fibers,and was placed in chamber with different vacuum states.The sample was excited via a 1020nm,3W laser.A temperature drop from room temperature of the sample was about△T≈12K under standard pressure,and△T≈26K under high vacuum.As for standard pressure state,thermal convection load of air was about11.23mW,thermal conduction load of the fibers was about0.03mW,thermal radiation load of the chamber was about4.8mW.As for high vacuum state,convection load of air was about0.03mW,conduction load of the fibers was about0.07mW,radiation load of the chamber was about10.4mW.As experimental results show,with the decrease of the pressure of the chamber from-10^5Pa to-10^3Pa,convection load of air is almost negligible,radiation load of the chamber becomes the most important thermal load of the refrigeration sample.