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

Abstract

Raman spectra of a series of Yb3+‐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 S4 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.