Laser cooling of Yb3+-doped BaY2F8 single crystal

We observed laser cooling in a 2.5% Yb3+-doped BaY2F8 single crystal. Single crystals have been grown by the Czochralski technique. The absorption spectra and the visible emission properties have been measured at room temperature. A temperature drop of almost 4 K was obtained by pumping the crystal with 3 W of laser radiation at 1025 nm in single pass configuration.