Investigation On Holographic Storage Properties Of Ruthenium-Series Doped LiNbO₃ Crystals

Volume holographic storage technology becomes the research focus in holographic storage area because of its large storage capacity,fast response speed and the hard-lost information. The suitable material for holographic storage is Fe:LiNbO₃ crystal, however, the slow response speed and low optical damage resistance ability limit its development in the holographic storage area. In order to improve the response speed and optical damage resistance ability, Ru, Mg and Zn ions were chosen to dope in Fe:LiNbO₃ crystal. Mg:Ru:Fe:LiNbO₃ crystals with different Mg concentration and Zn:Ru:Fe:LiNbO₃ crystals with different Zn concentration were grown by Czochralski method, and these crystals have no defects including crack and the growth streak at the macroscopic.The defect structures of the doped LiNbO₃ crystals were investigated by X-ray powder diffraction, infrared OH- transmission spectra and Ultraviolet-Visible(UV-Vis) absorption spectra. Based on the spectra results of X-ray powder diffraction experiments, lattice constants was used to analyse the place Mg or Zn ions occupied. Through the position shift of OH- absorption peak, the ions threshold concentration and the occupy in doped LiNbO₃ crystals were obtained. When the Mg or Zn concentrations have reached or exceeded the threshold concentration, the OH- absorption peak shifts to 3535(3529) cm-1, Mg or Zn begin to the normal Nb site. Also the Ultraviolet-Visible(UV-Vis) absorption spectra can be used to analyse the place Mg or Zn ions occupied in doped LiNbO₃ crystals.Two beam coupling method is used to study the holographic storage properties with the pump light of 476nm, 532nm or 633nm. Transmission facula distortion and light-induced scattering method are used to measure optical damage resistance ability. The dual-wavelength nonvolatile storage experiment is set up, in which Kr+ laser works as the recording beam and the He-Ne laser works as the detecting beam. Then, the holographic storage experiment is carried on. The experiment results above show holographic storage properties and the nonvolatile holographic storage properties of Mg(7mol%):Ru:Fe:LiNbO₃ crystal and Zn(7mol%):Ru:Fe:LiNbO₃ crystal are improved, compared with that of Ru:Fe:LiNbO₃ crystal.