First demonstration of an all-solid-state optical cryocooler

摘要

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.