EVALUATION OF ABSORPTION AND EMISSION PROPERTIES OF YB-3+ DOPED CRYSTALS FOR LASER APPLICATIONS

The emission and absorption properties of numerous host crystals doped with Yb3+ ions have been studied. The hosts which have been selected present a variety of crystal field environments for the ytterbium ion, including fluoride and oxide crystals with six-, seven-, eight-, nine- and twelvefold coordinated substitutional sites. The crystal compounds include LiYF4, LaF3, SrF2, BaF2, KCaF3, KY3F10, Rb2NaYF6, BaY2F8, Y2SiO5, Y3Al5O12, YAlO3, LuPO4, Ca5(PO4)3F, LiYO2, and ScBO3. Spectral determinations have been made of the resonant absorption and emission cross sections between 850 and 1100 nm, and the emission decay times of the upper laser level have been measured. The emission cross sections have been evaluated using the absorption cross section and principle of reciprocity, and again using the Fuchtbauer-Ladenburg formula. Agreement between the two methods is within 20% for most materials. The results of this survey are discussed in the framework of requirements for an effective diode-pumped Yb3+ laser system. Ca5(PO4)3F:Yb is predicted to exhibit the most useful laser properties and is expected to be superior to Y3Al5O12:Yb in many key spectroscopic parameter values.