Laser Cooling of Yb3+-doped CaF2 and SrF2 Crystals

We report on laser cooling of ytterbium (Yb3+)-doped fluorite-type crystals for the first time. Czochralski-grown Yb3+(5 at.%):CaF2 and Yb3+(5 at.%):SrF2 single crystals are cooled by laser excitation at 1040 nm.