Ytterbium-doped yttrium aluminium borate (Yb:YAB) crystals with high Yb3+ concentration have been obtained by the top-seeded solution growth techniques. The polarized absorption spectra, fluorescence spectra and lifetime of 65.5 at % Yb3+-doped YAB crystal were measured at room temperature. The spectroscopic parameters of the crystal were compared with those of low Yb3+-doped YAB crystal. The results demonstrated that the Yb:YAB crystals with high Yb3+ concentration are potential candidates for efficient microchip laser media. (C) 2004 Elsevier B.V. All rights reserved.