| This dissertation is a laser-cooling experimental study of 5 mol%dopedYb3+:LuLi F4 crystal.The research content was mainly divided into three parts:Firstly,we studied the physical properties of Yb3+:LuLi F4 crystal.We described the selection principles of rare earth elements and host materials,and measured the average fluorescence wavelength and absorption coefficient of the sample.As the results showed,the average fluorescence wavelength manifested red-shift,and the absorption coefficient reduced with the decreasing temperature of the sample,respectively.Secondly,we studied laser cooling behavior of the sample under the high vacuum state(10-3 Pa).When the sample was pumped by a laser with wavelength of 1020 nm and power of 25 W,a temperature drop of the sample from room temperature were?T?115 K,and the correlation cooling coefficient was about0.677%.As the results showed,the minimum achievable laser-cooling temperature of the sample was about 126.5 K.Thirdly,we studied the thermal load management mechanism of the sample under different pressure states.When the pressure of the cavity decreased from105 Pa to10-3 Pa,the conductivity of air convection reduced from 9.36×10-4 W/K to 1.0×10-6 W/K,and the conductivity of the cavity radiation keep4.0×10-4 W/K.As the results showed,how to reduce the radiation load of the cavity effectively,and break through the scope of liquid nitrogen temperature,become the key problem of the study of laser-cooling Yb3+:LuLiF4 crystal. |
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