Effect of Zr4+ concentration on optical properties and defect structure of Zr:Ho:LiNbO3 crystals

Zr:Ho:LiNbO3 crystals with different concentrations of Zr4+ were prepared by Czochralski method. The internal structure changes and the occupancy of doped ions were analyzed by X-ray diffraction (XRD). The effective segregation coefficient was analyzed by inductively coupled plasma atomic emission spectrometer (ICP-AES), and the optical homogeneity was analyzed by birefringence gradient method. The experimental results show that doping does not change the inherent structure of the crystal, the threshold concentration of Zr4+ is 1 mol%, and the occupation of Zr4+ changes before and after the threshold concentration. The effective separation coefficient of Zr4+ and Ho3+ decreases with the increase of ZrO2 concentration. The optical homogeneity of the crystal will increase with the increase of ZrO2 concentration, and the optical homogeneity of the crystal is strongest when the concentration of ZrO2 reaches the maximum (4 mol%).