Spectroscopic evaluation of Yb/sup 3+/-doped glasses for optical refrigeration

The absorption and emission properties of Yb/sup 3+/-doped ZBLANP, BIGaZYT and QX/Yb phosphate glasses are studied to evaluate their potential for laser-induced fluorescent cooling or optical refrigeration. The efficiency of optical refrigeration increases with pump wavelength in the anti-Stokes region. The cooling efficiencies of the three glasses as a function of temperature are evaluated at the wavelength /spl lambda/p corresponding to the absorption coefficient of 10/sup -3/ cm/sup -1/. For temperatures <110 K, the cooling efficiency of the BIGaZYT glass may be more than twice that of the ZBLANP.