Anti-Stokes laser-induced internal cooling ofYb3+-doped glasses

Anti-Stokes cooling between room temperature and 77 K in a fluorochloride glass (CNBZn) and a fluoride glass (BIG) doped with 1 mol % of ${\mathrm{YbF}}_3$ has been demonstrated by using collinear photothermal deflection and conventional laser excitation spectroscopies under high photon irradiances. The cooling efficiency for CNBZn glass which is ∼2.0% relative to the absorbed laser power at 1010 nm and 300 K falls about 20% at 77 K. The cooling efficiency for BIG glass was only ∼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 relation with the vibrational properties of the material.