Laser cooling of the Yb3+-doped LuLiF4 single crystal for optical refrigeration

Abstract

A vibration-free, optical cooling refrigerator may imply revolutionary applications in different fields, therefore it is vital to explore new materials suitable for laser cooling below the cryogenic temperature. Here we demonstrate that the Yb3+-doped LuLiF4 crystal is a promising material that could reach the cryogenic temperature limit (123 K) or even lower. With the doping concentration of 7.5%, the Yb3+-doped LuLiF4 crystal can be optically cooled down from the room temperature to 141.8 K in a double-pass setup. Provided with better purity and multiple-pass of laser cooling in the crystal, the temperature limit can even reach as low as 89 K for the 7.5% Yb3+-doped LuLiF4 crystal, thus making it a competitive candidate for laser cooling below the cryogenic temperature.