Defect structure and holographic storage properties of LiNbO_3:Zr:Fe:Cu crystals with various Li/Nb ratios

摘要

A series of LiNbO3:Zr:Fe:Cu single crystals with various Li/Nb ratios ranging from 0.946 to 1.38 were grown in air by the Czochralski method. Both X-ray powder diffraction and ultraviolet absorption spectra have been examined, and are discussed with regard to the defect structure of the as-grown crystals. In addition, the conventional two-wave coupling experiment has been conducted with 532 nm laser to reveal the holographic storage properties. The results have shown the macroscopic photorefractive properties to correspond well to the microscopic defect structure changing with the composition. More specifically, LiNbO3:Zr:Fe:Cu crystals possess at once relatively high sensitivity, fast response time and dynamic range comparable with that of LiNbO3:Zr:Fe crystals, and at the same time maintain high saturation diffraction efficiency (up to 68%) close to that of typical photorefractive LiNbO3:Fe crystals (70%), as such denoting their potential as prominent holographic storage media.