Optical Refrigeration and Radiation-Balanced Lasers

摘要

The laser cooling of solids by anti-Stokes emission has been advancing on many fronts. Work on the laser cooling of rare earth-doped solids has expanded to include materials comprised of ytterbium, thulium, holmium, and erbium dopants in a variety of crystal and glass hosts. The growth techniques and quality of these cooling materials have greatly improved. With these improvements, laser cooling may soon approach liquid nitrogen temperatures. Rare earth-based cryogenic optical refrigerators may find applications in cooling infrared cameras, low-noise electronics, high-purity germanium gamma ray spectrometers, and high-temperature superconductors. Laser cooling in semiconductor devices has also been pursued intensively, and net cooling in CdS nanostructures was recently reported. In parallel, "athermal" or radiation-balanced lasers, which exploit anti-Stokes fluorescence to balance the heat generated by quantum defect in rare earth-doped lasers, may enable the development of extremely high-power lasers with excellent beam quality.