Nonvolatile two-color holographic recording gated by incoherent ultraviolet(UV)light centered at 365 nm is investigated in near-stoichiometric lithium niobate crystals.The influence of thermal treatment on the two-color recording is studied.The results show that thermal reduction tends to improve the two-color recording performance,whereas thermal oxidation degrades the two-color recording.With an incoherent 0.2-W/cm^2 UV gating light and a 0.25-W/cm^2 semiconductor recording laser at 780 nm,a two-color recording sensitivity of 4×10^(-3)cm/J and a recording dynamic range characterized by M/# of 0.12 are achieved in a 2.2-mm thermally reduced near-stoichiometric lithium niobate crystal.We attribute the improvement to the prolonged lifetime of small polarons and the increased absorption at the gating wavelength due to thermal reduction.
