DEFECTS IN YAG-YB CRYSTALS

A perturbed F center associated with rare earth ion was identified in YAG:Yb boules with absorption bands at 370 and 625 nm. The dislocation density in the crystal is determined to be less than 100 units cm(2). From the absorption and emission spectras of YAG:Yb the trails of Er3 + and Ho3+ were detected. Hydroxyl groups were also found in the TAG:Y b crystals. To ensure high laser efficiency of diode pumped YAG:Yb sys tem, the practical doping concentration of Yb3+ must not exceed 20 atm %. (C) 1998 American Institute of Physics. [S0021-8979(98)00705-1].