First demonstration of an all-solid-state optical cryocooler

Markus P Hehlen; Junwei Meng; Alexander R Albrecht; Eric R Lee; Aram Gragossian; Steven P Love; Christopher E Hamilton; Richard I Epstein; Mansoor Sheik-Bahae

doi:10.1038/s41377-018-0028-7

First demonstration of an all-solid-state optical cryocooler

Light Sci Appl. 2018 Jun 6:7:15. doi: 10.1038/s41377-018-0028-7. eCollection 2018.

Authors

Markus P Hehlen^{1

2}, Junwei Meng², Alexander R Albrecht², Eric R Lee², Aram Gragossian², Steven P Love¹, Christopher E Hamilton¹, Richard I Epstein², Mansoor Sheik-Bahae²

Affiliations

¹ 1Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 USA.
² 2Department of Physics & Astronomy, University of New Mexico, Albuquerque, NM 87131 USA.

Abstract

Solid-state optical refrigeration uses anti-Stokes fluorescence to cool macroscopic objects to cryogenic temperatures without vibrations. Crystals such as Yb³⁺-doped YLiF₄ (YLF:Yb) have previously been laser-cooled to 91 K. In this study, we show for the first time laser cooling of a payload connected to a cooling crystal. A YLF:Yb crystal was placed inside a Herriott cell and pumped with a 1020-nm laser (47 W) to cool a HgCdTe sensor that is part of a working Fourier Transform Infrared (FTIR) spectrometer to 135 K. This first demonstration of an all-solid-state optical cryocooler was enabled by careful control of the various desired and undesired heat flows. Fluorescence heating of the payload was minimized by using a single-kink YLF thermal link between the YLF:Yb cooling crystal and the copper coldfinger that held the HgCdTe sensor. The adhesive-free bond between YLF and YLF:Yb showed excellent thermal reliability. This laser-cooled assembly was then supported by silica aerogel cylinders inside a vacuum clamshell to minimize undesired conductive and radiative heat loads from the warm surroundings. Our structure can serve as a baseline for future optical cryocooler devices.