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Five atomic percent Yb:YAG laser crystals have been grown by Czochralski (CZ) and temperature gradient technique (TGT) method. The absorption spectra of as-grown and annealed Yb:YAG crystals have been investigated. There is no Yb2+ and color center absorption in TGT-grown Yb:YAG crystals; the absorption peak of CZ-grown Yb:YAG crystals after O2-annealing at 255 nm is attributed to Fe3+ ions. The longitudinal distribution of Yb3+ ions has also been studied; TGT-grown Yb:YAG crystal has a larger distributing inhomogeneity of Yb3+ although it is large sized. [Copyright &y& Elsevier]

Abstract: The Yb (10%):GGG and Yb (30%): GGG crystals have been grown by the Czochralski method. The chemical compositions are: Yb1.07Gd1.74Ga5.19O12 and Yb0.33Gd2.47Ga5.2O12. The absorption and emission spectra of Yb:GGG crystal at room temperature have been measured. The spectroscopic parameters of Yb:GGG and Yb:YAG have been compared. Optical absorption spectra of Yb:GGG show 4f–4f transitions related to Gd3+ ion around 300nm, and also an onset of charge transfer (CT) transitions from oxygen ligands to Gd3+ or Yb3+ cations below 240nm.The CT absorption of Yb3+ is largely overlapped by that of Gd3+ ions. [Copyright &y& Elsevier]