Theoretical Study On Laser Cooling Of Tm～(3+)-doped Materials

Laser cooling of solids, based on the anti-Stokes fluorescence, is a new developed cooling technique, and has some novel and unique properties as follows: all optical cooling, no mechanical vibration, without electromagnetic interference, a long time of continuous operation, and so on. Thulium-doped fluorozirconate (ZBLANP) glass has become one of the promising materials in the field of the laser cooling of solids. In this thesis, the basic principle on laser cooling of solids is first introduced, and some main factors that influence the effect of laser cooling of solids in experiments are discussed in some detail. Afterward, the laser cooling ofT_m³⁺ : ZBLANP materials is studied in detail. Finally, the applied prospect on lasercooling of solid materials and development of optical refrigerators are briefly discussed and looked ahead.We developed a simple theoretical model to analyze some basic questions in the laser cooling of solids. The influences of the fluorescent quantum efficiency, the pump power, the change of fluorescence wavelength and the black-body radiation onthe laser cooling effect for the T_m³⁺ : ZBLANP fiber are discussed in some detail, andsome interesting and important results are obtained. These results will provide the reliable theoretical basis for further experimental study on the laser cooling of theT_m³⁺ : ZBLANP fiber.We propose a new scheme to realize laser cooling of Tm³⁺ -doped glass (ZrF₄ -BaF₂-LaF₃-NaF-PbF₂) ZBLANP. In this scheme, the absorption of pumping laser power is greatly increased by multiple reflections between two sets of mirrors with a high reflectance, and when the incidence angle of the pumping laser is equal to a Brewster angle, the reflection losses on the two end-faces of the sample will be reduced to nearly zero. The cooling temperature of the bulk sample and its cooling time constant in this scheme are calculated in detail, the relationship between the cooling power and reflection number is analyzed as the incidence laser power is 1.0 W,...