| Optical volume holographic storage technology has attracted attention for its high storage density, large storage capacity and fast access speed etc. The practical application of volume holographic storage technology depends on the performance of the storage material. Being a potential material for volume holographic storage, the defects of Li Nb O3 crystals, such as slow response speed, strong scattering noise, limit its further development. It’s well known that adding some impurity ions to the crystal or increase [Li]/[Nb] ratio can effectively improve the performance of the crystal. Therefore, this paper chooses Hf:Mn:Fe:Li Nb O3 crystals with different [Li]/[Nb] as the research objects, and conducts theoretical analysis and systematic researches on its holographic storage properties.First of all, Hf:Mn:Fe:Li Nb O3 crystals were grown by the Czochralski method, whose [Li]/[Nb] ratio are 0.946, 1.05, 1.20 and 1.38 respectively. After the process of polarization, orientation, cutting, lapping and polishing, the crystals turned into samples that can be used for volume holographic storage.Secondly, the X-ray powder diffraction measurements were performed to conduct phase analysis for crystal samples and determinate the crystal structure. The results showed that the Hf:Mn:Fe:Li Nb O3 crystals retain the original crystal structure, but the lattice constant changed slightly; At the same time, the infrared transmission spectra and ultraviolet-visible absorption spectrum were measured in order to know the site substitution of the doped ions in the crystal. The results indicated that with the increase of [Li]/[Nb], the crystal OH- absorption peak position did not significantly move. And the crystal base absorption edge shifted to purple firstly and then shifted to red.Again, the diffraction efficiency were tested, write and erase time of the crystal through two-beam coupling experiment. Then calculated the photorefractive sensitivity and dynamic range under 532 nm band. The results showed that the Hf:Mn:Fe:Li Nb O3 crystal possess good photorefractive performance. What’s more, the [Li]/[Nb] ratio played an important role in the adjustment of the crystal parameters.Finally, the direct transmission facula distortion method was used to study the light scattering properties of the crystal under 532 nm band. Researches showed that Hf:Mn:Fe:Li Nb O3 crystals have stronger resistance threshold to the light damage and the scattering noise in the crystals can be inhibited effectively by improving the [Li]/[Nb] ratio. |
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