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Provides information on a study analyzing the threshold effect of the incident light intensity for the photorefractive light-induced scattering in LiNbO3:Fe,M, (M=Mg2+, Zn2+, In3+) crystals. Information on the theoretical analysis; Detailed information on the numerical simulation; Conclusions reached on the experiment.

Photorefractive properties of congruent lithium niobate crystals codoped with HfO2 and Fe2O3 were investigated and it was found that Fe ions are still located at Li sites as photorefractive centers when the doping concentration of HfO2 goes above the threshold value. As a result, their photorefractive response speed and sensitivity are significantly enhanced. Meanwhile, the high saturation diffraction efficiency is still maintained. Experimental results definitely show that Hf is now the most effective doping element for LiNbO3:Fe crystal to improve its photorefractive properties. [ABSTRACT FROM AUTHOR]

Abstract: We describe the ultraviolet-light one-color photorefraction (UV-OPR) at 351nm in LiNbO3 crystals with different Mg-doping concentrations and [Li]/[Nb] ratios. It is shown that as the Mg-doping concentration and/or the [Li]/[Nb] ratio increase, the refractive index change and the two-beam coupling gain increase but the response time decreases. It is also shown that the recording sensitivity as large as ∼27cm/J is obtainable at a recording intensity of ∼1W/cm2 in near-stoichiometric LiNbO3 doped with 2mol% Mg. This sensitivity is approximately one order of magnitude higher than those for other LiNbO3 crystals. We also describe the ultraviolet-light-gating two-color photorefraction (UV-TPR) using 365nm gating and 633nm recording beams in LiNbO3 crystals with different Mg-doping concentrations and [Li]/[Nb] ratios. It is shown that UV-TPR is only observed in near-stoichiometric crystals and the grating-formation dynamics strongly depend on the Mg concentration. [Copyright &y& Elsevier]

Abstract: Several near-stoichiometric lithium niobate crystals with the doping concentration of Mg near the second threshold were prepared by vapor transport equilibrium technique. All these samples show no laser beam distortion under a light intensity of 26MW/cm2, that is three orders of magnitude higher than that of 5mol% Mg doped congruent LiNbO3. And the light-induced refractive index (Δn) in one of them is as small as 4.6×10−7, which is two orders of magnitude lower than that of congruent crystals. [Copyright &y& Elsevier]