Study On The Preparation And Optical Properties Of Magnesium,Ytterbium And Holmium Co-doped Lithium Niobate Crystal

In this paper, a series of Yb?1mol%?: Ho?1mol%?: LiNbO₃ crystals doped with various concentration of Mg²⁺?1, 3, 5 and 7mol%? were grown by the Czochralski technique, and the influence of magnesium concentration on the intrinsic defects, site occupancy of the doping ions in the crystal and the optical damage resistance ability of Mg: Yb: Ho: LiNbO₃ crystals were analyzed.The concentrations of Mg²⁺, Yb³⁺ and Ho³⁺ ions were measured by inductive couple plasma atomic emission spectrometer?ICP-AES?. The results showed that the Mg²⁺ doping concentration suppresses Yb³⁺ and Ho³⁺ ions into crystal. The infrared transmission spectrum was used to analyze the defect structure and determine the situation site of Mg²⁺ ions. According to the results, the following conclusions were obtained: It substitutes Li+ site to form+LiMg by priority replacing anti-bit Nb defects when Mg²⁺ doped concentration was below its threshold concentration. When the Mg²⁺ doping concentration reached or exceeded the threshold concentration in Mg: Yb: Ho: LiNbO₃ crystals, Mg²⁺ begin to substitute Li site and Nb site of normal lattice to form3- +Nb LiMg-3Mg, at this time, Mg²⁺ions affected the positions of Yb³⁺and Ho³⁺ ions.The optical homogeneity of Mg: Yb: Ho: LiNbO₃ crystal was detected by the birefringence gradient method, the results demonstrated that the optical homogeneity is getting better with the increase of the Mg²⁺ doping concentration. The optical damage resistance ability of Mg: Yb: Ho: LiNbO₃ crystal was measured by the light scattering threshold energy flow method and the transmission facula distortion method. It shows that the optical damage resistance ability increased with the rise of the Mg²⁺ doping concentration.According to the results, the Mg?7mol%?: Yb?1mol%?: Ho?1mol%?: LiNbO₃ has the most excellent optical homogeneity and the strongest optical damage resistance ability in this series.