Effect of Hf4+ concentration on defect structure and optical properties of Yb:Tm:LiNbO3 crystals

Hf:Yb:Tm:LiNbO3 crystals with different Hf4+ concentration (2, 4 and 6mol%)were successfully prepared by Czochralski method. The concentrations of Hf4+, Yb3+ and Tm3+ ions were analyzed via inductive couple plasma atomic emission spectrometer (ICP-AES). The influence of Hf-4(+) doping concentration on defect structure and doping occupancy in Hf:Yb:Tm:LiNbO3 crystal was measured by UV-VIS-NIR absorption spectroscopy. The optical damage resistance of lif:Yb:Tm:LiNbO3 crystal was analyzed by light scattering threshold energy flow method. It is found that the optical damage resistance of Hf:Yb:Tm:LiNbO3 crystal can be effectively improved by increasing the doping concentration of Hf-4(+) ions. When Hf-4(+) concentration increased to 6mol%, the optical damage resistance of the crystal is 48 times that of the 2mol% Hf-4(+) doped crystal.