First Solid-state Cooling Below 100K
AIR FORCE RESEARCH LAB KIRTLAND AFB NM
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Advances in material purity and laser light absorption offer new possibilities for vibration-free cryogenic cooling. Material properties change as a function of temperature, and cryogenic refrigeration allows us to obtain very useful properties not available at higher temperatures. For instance, in the temperature range 77 150K, superconductivity, long- and mid-wave IR detectors, and ultra-stable laser cavities become usable.1 Currently, these low temperatures are reached using liquid or solid cryogens or mechanical refrigerators. Unfortunately, liquids and solids require regular attention to refill after evaporating away, and mechanical refrigerators introduce vibrational noise and mechanically wear over time. Space-based applications, and ultra-stable laser cavities in particular, cannot tolerate these drawbacks. A solid-state solution is preferable for its inherent vibration-free operation and potentially long lifetime. Optical refrigeration via anti-Stokes fluorescence is currently the only solid-state cooling technology capable of reaching cryogenic temperatures.
- Physical Chemistry
- Lasers and Masers
- Solid State Physics