The Performance of a Laboratory Optical Refrigerator

Abstract

Optical refrigeration using anti-Stokes fluorescence in solids has several advantages over more conventional techniques, including low mass, low volume, low cost and no vibration. It has been the topic of analysis and experimental work by several organizations. We recently demonstrated the first optical refrigerator which cooled an attached load 11.8 degrees C below the surroundings. Our laboratory refrigerator is pumped by a 30 watt, tunable, ytterbium doped yttrium aluminum garnet (Yb:YAG), continuous wave, disk laser and uses a ytterbium doped fluorescent cooling element external to the laser cavity. In this paper, we report on the operation of our laboratory optical refrigerator at different pump wavelengths, power inputs and loads. We have modeled the refrigeration cycle based on the fluorescent material emission and absorption data at ambient and reduced temperature. We have also calculated the expected heat transfer into the refrigerator cold assembly. The measured performance of the refrigerator is presented and compared to the expected performance.