Anti-Stokes laser-induced internal cooling of Yb3+-doped glasses

Anti-Stokes cooling between room temperature and 77 K in a fluorochloride g lass (CNBZn) and a fluoride glass (BIG) doped with 1 mol % of YbF3 has been demonstrated by using collinear photothermal deflection and conventional l aser excitation spectroscopies under high photon irradiances. The cooling e fficiency for CNBZn glass which is similar to 2.0% relative to the absorbed laser power at 1010 nm and 300 K falls about 20% at 77 K. The cooling effi ciency for BIG glass was only similar to 0.6% at room temperature. A model accounting for the photon-ion-phonon interaction is in good agreement with the observed temperature dependence of the cooling process and shows its re lation with the vibrational properties of the material.