On the origin of anti-Stokes laser-induced cooling of Yb3+-doped glass

Anti-Stokes cooling between room temperature and 77 K in a new fluorochlori de glass (CNBZn) doped with 1 mol% of YbF3 has been demonstrated by using c ollinear photothermal deflection and conventional laser excitation spectros copies under high photon irradiances. The cooling efficiency of CNBZn glass which is similar to2.0% relative to the absorbed laser power at 1010 nm an d 300 K falls by about 20% at 77 K. A model accounting for the photon-ion-p honon interaction is in good agreement with the observed temperature depend ence of the cooling process and shows its relation with the vibrational pro perties of the material. (C) 2001 Elsevier Science B.V. All rights reserved .