掺杂SBN晶体在光信息处理中的应用研究

【作者】 吴建军；

【导师】 赵建林；

【作者基本信息】 西北工业大学 ， 光学， 2001， 硕士

【摘要】 本文首先讨论了光折变波耦合过程中光折变晶体的光轴取向、作用光波的偏振方向以及晶体内所形成的空间电荷场的方向三者之间的关系，用修正后的公式具体计算了光折变SBN和LiNbO₃晶体在各种不同情况下的有效电光系数，理论分析的结果与实验结果完全吻合。其次，从实验上研究了SBN:Cr、KNSBN:Cu、LiNbO₃:Fe晶体的全息读写特性，并且在SBN:Cr和KNSBN:Cu晶体中利用光折变二波耦合实现了光学图像的放大和边缘增强，利用参考光波对物光波各空间频率成分的非线性放大特性对此做出了合理的解释。进而，利用掺杂浓度1000ppm的SBN:Cr晶体实现了关联记忆及匹配相关识别，并在该晶体中观察到了四波混频相位共轭反射现象，测得该晶体的相位共轭反射率最大为58％利用相位共轭光实现了畸变图像的畸变消除，观察并记录了其中光感应散射的写入过程。在本文的最后，对一些实现边缘增强的方法作了比较，讨论了耦合条件分析方法的局限性、耦合与全息写入的关系、最佳耦合角的选取等，探讨了SBN:Cr晶体在相关识别和信号中继放大方面应用的可能性。更多还原

【Abstract】 In this thesis the relation among the crystal axis?orientation, the polarized orientation of incident beams and the orientation of the spatial charge field are discussed firstly. The modified formulas are used to calculate the efficient electro-optic coefficient of SBN and LiNbO3 crystals in some different cases. The analysis results are perfectly according with the experiment results.In the following part, the writing and reading character of holograms is investigated in SBN:Cr~ KNSBN:Cu and LiNbO3:Fe crystals. Optic image amplifying and the edge enhancement phenomena are realized through two-beam coupling in the two former crystals. Theory analysis shows the origin of the edge enhancement is the different amplifying ratio of pump beam to signal beam.The correlated identification and the phase conjugation are achieved in 1 000ppm Cr-doped SBN:Cr crystal, and the measured phase conjugation reflectivity is 58%. Using the phase conjugation beam, the phase distortion of signal beam is rectified. The process of optic-induced scattering, coming from the stronger pump beam, is also observed. The forming speed of optic-induced scattering is found to increase as the signal beam is added.In the last part, such problems as coupling condition analysis, the relation of coupling and storage, the best coupling angle, and some applications are also discussed.更多还原