OH^- absorption and nonvolatile holographic storage properties in Mg:Ru:Fe:LiNbO₃ crystal as a function of Mg concentration

Mg:Ru:Fe:LiNbO₃ crystals with various concentrations of MgO (in mole) and fixed content of RuO₂ and Fe₂O₃ (in mass) are grown with the Czochralski method from the congruent melt. Their infrared transmission spectra are measured and discussed to investigate the defect structure. With the increase of Mg²⁺ concentration the blue nonvolatile holographic storage capability is enhanced. The nonvolatile holographic storage properties of dual-wavelength recording of Mg(7 mol%):Ru:Fe:LiNbO₃ nonvolatile diffraction efficiency, response time and nonvolatile sensitivity reach 59.8%, 70 s, and 1.04 cm/J, respectively. Comparing Mg(7 mol%):Ru:Fe:LiNbO₃ with Ru:Fe:LiNbO₃ crystal, the response time is shortened apparently. The nonvolatile diffraction efficiency and sensitivity are raised largely. The mechanism in blue photorefractive nonvolatile holographic storage is discussed.