Optical Refrigeration for Dramatically Improved Cryogenic Technology.

摘要

ThermoDynamic Films LLC (TDF), in collaboration with the University of New Mexico (UNM), improved the performance of optical refrigerators for deployment space-borne missions and terrestrial applications. They have optimized the ytterbium doping concentrations the optical refrigerator cooling elements. With these advances the TDF/UNM collaboration has been able to an optical-refrigerator cooling element comprised of an ytterbium-doped yttrium lithium fluoride (Yb:YLF) crystal from room temperature to 93 K. This is the world record for optical refrigeration (or for any solid-state cooling technology). They have developed an externally pumped optical cryocooler device, which enhances the energy density of laser light in the cooling cavity to increase the efficiency of converting laser power into cooling power. They designed and built high thermal conductivity links that connect cooling crystal to the load while providing shielding of the cold elements from the intense fluorescence generated in the cooling process. They also developed an optical refrigeration scheme based on intracavity-enhanced absorption that uses optically pumped surface-emitting lasers.