Core region and optical properties of Er3+ doped Y3Al5O12 single crystals

Er3+ doped Y3Al5O12 (Er: YAG) single crystals, in which the concentrations of Er3+ ion were 5, 7.3, 8, and 10 at.%, were grown by the Czochralski method under nitrogen atmosphere. The <111> oriented Er : YAG single crystals with diameters of up to 50 mm were grown at a pulling rate of 1.0 mm/h and rotation rate of 10 rpm. The thick part of the core region was generated mainly when there was a diameter change during the crystal growth. The concentrations of Er3+ ion in the crystals were the same as it was in the melt. Er3+ concentration of core region was slightly higher than the other regions in the compositional analysis. The fluorescence lifetime was saturated according to the increase of Er3+ doping concentrations.