Extremely High Quantum Efficiency and High Purity Rare-Earth-Doped Crystals for Solid-State Laser Cooling: Material Synthesis and Characterization
Technical Report,15 Jul 2015,14 Jul 2018
University of New Mexico Albuquerque United States
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This project concerned investigating the growth and characterization of extremely high-purity low-phonon energy crystals doped with rare-earth ions ytterbium, thulium and holmium. The overall goals are 1 achieving lower temperatures approaching 70K and beyond, 2 improving efficiency, and 3 enhancing the cooling power density. The recent record cooling studies have been obtained in high-purity Yb-doped YLiF4 YLF crystals. Further advances in this field should address material selection and synthesis involving a smaller ground state manifold splitting Stark splitting, b higher doping concentration without degrading the external quantum efficiency EQE, c the use of dopants with smaller energy gap such as Tm, Ho and Dy, and d mitigation of parasitic absorption by identifying the impurity source and purifying the starting materials. In this project, we closely collaborate with Dr. Markus Hehlen at Los Alamos National Laboratory LANL who is the world leading material scientist in RE-doped crystals for optical refrigeration.
- Solid State Physics