Raman scattering investigation of Yb : YAG crystals grown by the Czochralski method

Raman spectra of a series of yb(3+)-doped YAG crystals were obtained with Yb3+ concentrations up to 100 at.%. Single crystals were successfully grown. No abrupt change of the spectral pattern of the Raman modes as a function of Yb3+ doping concentration was observed. From the spectral changes, it is noted that the Raman peaks shift towards lower wavenumbers in the range <450 cm(-1) and towards higher wavenumbers in the range >450 cm(-1) with increasing Yb3+ doping concentration. It is proposed that Raman modes with wavenumbers <450 cm(-1) are the yttrium or ytterbium ions lattice vibrational modes and that the other phonon peaks can then be assigned to internal modes associated with the (AlO4) tetrahedra Of S-4 symmetry. The doping concentration of Yb3+ does not influence the spectral properties and lattice vibrations drastically, so that a stable and more efficient Yb:YAG laser may be obtained with highly doped Yb3+ contents. Copyright (C) 2003 John Wiley Sons, Ltd.