研究了非挥发全息记录中由于紫外光的强吸收而引起的光栅非均匀性,分析了这种非均匀性对光栅衍射效率的影响。结果显示,非均匀性致使光折变光栅的平均强度减弱,衍射效率降低。提出了采用两束等光强的敏化紫外光由晶体两侧入射的优化方案以改善光栅的均匀性,提高光栅的衍射效率。通过联立两中心带输运物质方程和双光束耦合波方程,进行了相应的理论模拟,并给出实验验证。结果表明双侧紫外光照射能够实现均匀性较好的光栅,是提高衍射效率的有效途径之一。

The grating non-uniformity of the nonvolatile volume hologram recording in doubly doped LiNbO3 (LN) crystals mainly caused by strong ultraviolet (UV) absorption is studied in detail. The average saturation space-charge field is small and the diffraction efficiency is low as a result of the non-uniformity of the grating. Optimization for the uniformity of the grating using two sensitizing beams from the two opposite sides of the crystals is performed. Theoretical simulations and experimental verification are presented. Well uniform gratings can be obtained and diffraction efficiency can be greatly enhanced by using this optimization scheme.