Yb3Al5O12 and highly doped Yb:YAG (50 at.-%) crystals were successfully grown using Czochralski methoa. X-ray powder diffraction (XRPD) experiments showed that YbAG and highly doped Yb:YAG crystals had the same structure as Yb3Al6O12 (YAG) crystal. The absorption, emission spectra and fluorescence lifetime of YbAG and highly doped Yb:YAG crystals at room temperature have also been studied, and spectral parameters have been compared with low doping Yb:YAG crystal. The results indicate that YbAG and highly doped Yb:YAG crystals are promising laser materials for high power laser output.