Recent advances in laser-induced cooling in rare-earth doped low phonon materials

摘要

The recent finding of new low phonon materials (both glasses and crystals) as rare-earth (RE) hosts that may significantly decrease the nonradiative emissions from excited state levels has renewed the interest in investigating new RE anti-Stokes emission channels. In this work we present, together with recent findings on cooling processes in Yb~(3+)-doped low phonon materials, the first experimental demonstration of anti-Stokes laser-induced cooling in the same matrices doped with Er~(3+): a low phonon KPb_2Cl_5 crystal and a fluorochloride glass. In order to assess the presence of internal cooling in these systems we used the photothermal deflection and conventional excitation spectroscopy techniques whereas the bulk cooling in the Er~(3+) -doped samples was detected by means of a calibrated thermal sensitive camera. The experimental results are in good agreement with the predictions of a model based on the presence of a second order process in the cooling mechanism.