Optical refrigeration is currently the only completely solid state cooling method capable of reaching cryogenic temperatures from room temperature. Optical cooling utilizing Yb:YLF as the refrigerant crystal has resulted in temperatures lower than 123K measured via a fluorescence thermometry technique. However, to be useful as a refrigerator this cooling crystal must be attached to a sensor or other payload. The phenomenology behind laser cooling, known as anti-Stokes fluorescence, has a relatively low efficiency which makes the system level optimization and limitation of parasitic losses imperative. We propose a variety of potential designs for a final optical refrigerator, enclosure and thermal link; calculate conductive and radiative losses, and estimate direct fluorescence reabsorption. Our simulated designs show losses between 60 and 255 mW, depending on geometry and enclosure choice, with a lower bound as low as 23 mW.

Date Published: 10 March 2015
PDF: 8 pages
Proc. SPIE 9380, Laser Refrigeration of Solids VIII, 93800J (10 March 2015); doi: 10.1117/12.2077254

Published in SPIE Proceedings Vol. 9380:
Laser Refrigeration of Solids VIII
Richard I. Epstein; Denis V. Seletskiy; Mansoor Sheik-Bahae, Editor(s)