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 $\text{100\hspace{0.17em}}{\mathrm{units\hspace{0.17em}cm}}^{\mathrm{2}}.$ From the absorption and emission spectras of YAG:Yb the trails of ${\mathrm{Er}}^{\mathrm{3+}}$ and ${\mathrm{Ho}}^{\mathrm{3+}}$ were detected. Hydroxyl groups were also found in the YAG:Yb crystals. To ensure high laser efficiency of diode pumped YAG:Yb system, the practical doping concentration of ${\mathrm{Yb}}^{\mathrm{3+}}$ must not exceed 20 atm%.