中文摘要：

采用基于密度泛函理论的第一性原理研究了Cu、Mn单掺及共掺LiNbO3晶体的电子结构和光学性质.结果显示,Cu、Mn掺杂LiNbO3晶体禁带中的杂质能级分别由Cu 3d轨道、Mn 3d轨道贡献;各掺杂体系的带隙均较纯LiNbO3晶体变窄.共掺晶体中Cu离子形成了较单掺时更浅的能级中心,并在2.87eV处有较强的吸收峰;Mn离子在1.73eV附近的吸收较单掺时减弱且中心略有偏移,在2.24eV处的非光折变峰与Mn3＋相关,这对吸收峰的变化被认为与Cu、Mn间电子转移相联系.相对Cu、Fe共掺LiNbO3晶体,Cu、Mn共掺LiNbO3晶体可以通过适当提高Cu离子浓度,来改善存储参量中的动态范围和记录灵敏度.由于同一深能级掺杂离子伴以不同浅能级掺离子将呈现出不同的吸收特征并影响存储性能,在共掺离子的配搭选择时对各待选配搭的模拟计算非常必要.

英文摘要：

The electronic structures and the absorption spectra of the Cu and Mn mono and co-doped LiNbO3 crystals were investigated by first-principles based on the density functional theory.The results show that the impurity energy levels of Cu and Mn doped LiNbO3 crystals appear within the band gaps,which are contributed by Cu 3 dorbital and Mn 3 dorbital.The band gap of each doped crystal is narrower than that of LiNbO3 crystal.There are three absorption peaks at 2.87 eV,2.24 eV and 1.73 eV respectively in Cu∶Mn∶LiNbO3 crystal.The first one and last one come from the electron transitions from Cu2＋and Mn2＋level to conduction band respectively.The second one is not photorefractive and relative with the concentrations of Mn3＋.Comparing with the Cu∶Fe∶LiNbO3 crystal,the recording center（Cu2＋）is deeper in Cu∶ Mn∶LiNbO3 crystal.In the two-center holographic recording,it is practicable to take suitable higher concentration of Cu ion in Cu∶ Mn∶LiNbO3 crystal to raise the dynamic range and sensitivity via enhancing the refractive-index change.The selecting of accompanying doping ion would affect the storage parameters,even if the recording center ion（deep level）is the same,so it′s necessary to select codoping ions according to the simulating datum of the different samples.