Rapid response of photorefraction in vanadium and magnesium co-doped lithium niobate

Vanadium and magnesium co-doped LiNbO₃ (LN) crystals were grown, and their photorefractive properties were studied in the visible spectral region. At 488 nm the shortest response time of 80 ms was achieved for an LN crystal co-doped with 0.1 mol% V₂O₅ and 6.0 mol% MgO, which is the more rapid than other reported doped LN crystals in the same wavelength region. The sensitivity of this crystal reaches 17 cm J⁻¹ with an adequate diffraction efficiency of 4.0%. A schematic diagram for energy level is proposed and discussed. Through the analysis of defect structure and absorption spectra, we found that the change of the vanadium ions occupancy from Li sites to Nb sites is responsible for significant shortening the response time. The rapid response of vanadium and magnesium co-doped LN crystal can play an excellent role in the field of dynamic holography and practical holographic 3D-storage applications. (paper)