Investigation of novel materials for laser-cooling application.

Cittadino G., Volpi A., Di Lieto A., Tonelli M.
  Mercoledì 28/09   10:00 - 13:00   Edificio Psicologia 2 - Aula 2B   II - Fisica della materia
Optical cooling is a process based on anti-Stokes fluorescence. It is possible to excite, using proper wavelengths, ions embedded inside a crystal host and to lower energy phonons of material. Emitted photons have energy higher than the absorbed one, due to the thermalization of the electronic population within the energy levels. Therefore the thermal energy and entropy are carried out from the material through the fluorescence of blue-shifted photons, obtaining the cooling effect. Several rare-earth--doped materials have shown optical-cooling performance. Now, investigation of materials, like 5% $Yb^{3+}:LiYF_{4}$, 7.5% $Yb^{3+}:LiYF_{4}$, 10% $Yb^{3+}:LiYF_{4}$ and 5% $Yb^{3+} - 16 ppmTm^{3+}:LiYF_{4}$, and set-up optimization have led to the best solid-state cryogenic results.