title: Novel approach for solid state cryocoolers.
abstract: Laser cooling in solids is based on anti-Stokes luminescence, via the annihilation of lattice phonons needed to compensate the energy of emitted photons, higher than absorbed ones. Usually the anti-Stokes process is obtained using a rare-earth active ion, like Yb. In this work we demonstrate a novel approach for optical cooling based not only to Yb anti-Stokes cycle but also to virtuous energy-transfer processes from the active ion, obtaining an increase of the cooling efficiency of a single crystal LiYF(4) (YLF) doped Yb at 5at.% with a controlled co-doping of 0.0016% Thulium ions. A model for efficiency enhancement based on Yb-Tm energy transfer is also suggested.
authors.forename: Azzurra
authors.initials: A
authors.lastname: Volpi
authors.forename: Alberto
authors.initials: A
authors.lastname: Di Lieto
authors.forename: Mauro
authors.initials: M
authors.lastname: Tonelli