重掺镁LiNbO3:Fe晶体的光谱与光折变特性研究

研究了重掺镁ＬｉＮｂＯ３：Ｆｅ晶体的透射光谱与光折变特性。结果表明,ＬｉＮｂＯ３：Ｆｅ晶体在重掺镁后,镁离子把晶体中的铁离子“挤”入铌位是重掺镁ＬｉＮｂＯ３：Ｆｅ晶体抗光折变的原因所在。在重掺镁（≥５ｍｏｌ％）ＬｉＮｂＯ３：Ｆｅ的 ,作为施主中心的Ｆｅ＾２＋的特征吸收“台阶”的消失和３５０４ｃｍ＾－１的ＯＨ吸收带的出现,都直接证明了铁离子从锂位进入了铌位,并以Ｆｅ＾３＋Ｎｂ的形式存在。     

掺铁铌酸锂（Fe：LiNbO_3）晶体薄片的大角光致散射的研究

本文报导了掺铁铌酸锂（Ｆｅ：ＬｉＮｂＯ＿３）光折变晶体薄片的大角光致散射实验观察结果，给出了定性机理分析，且分析了此现象的应用前景。     

掺稀土元素 Er~(3+) 的 LiNbO_3 波导激光器设计

掺稀土元素Ｅｒ３＋的ＬｉＮｂＯ３波导激光器设计卢文杰陈淑芬（北京理工大学光电工程系１０００８１）掺稀土元素Ｅｒ３＋的ＬｉＮｂＯ３通道型连续输出的波导激光器作为一种新型激光器，在光集成方面具有独特优势而显示出良好的发展前景。由于铌酸锂晶体材料的优点以及...     

LiNbO_3的抗光折变与它的OH~－谱研究

测试了不同掺杂，不同组分ＬｉＮｂＯ＿３样品的红外吸收谱．提出在一致熔化组分ＬｉＮｂＯ＿３晶体中，Ｎｂ可变价和Ｌｉ的空位模型。解释了ＯＨˉ谱的３峰结构。在掺镁阈值以上，用镁占铌位和铁占铌位的缺陷模型，解释了ＯＨˉ谱紫移及３５０４ｃｍ￣（－１）峰出现的原由，进而对镁占铌位和铁占铌位进行了肯定。     

光折变晶体KNbO3温度效应研究

以光折变效应的带输运模型为基础，研究了高阱密度下温度为光折变晶体折射率主稳态体相位栅效率之间的关系；分析铌酸钾（ＫＮｂＯ３）晶体的温度特性，给出了相应的     

近化学计量比掺铁铌酸锂晶体光折变中心的研究

对不同锂铌比的掺铁铌酸锂晶体的光折变光栅的写入与擦除过程进行了研究,发现单中心模型已经不适用于近化学计量比掺铁铌酸锂晶体的光折变过程.通过对光折变光栅的擦除曲线的拟合发现,近化学计量比掺铁铌酸锂晶体的擦除过程为双指数过程,说明对于近化学计量比掺铁铌酸锂晶体光折变中心为两种.     

近化学计量比Fe:LiTaO3晶体的光折变性能

采用顶部籽晶溶液法（TSSG）,生长直径约10-15mm,长度为10mm的近化学计量比掺铁铌酸锂（Fe：SLN）和近化学计量比掺铁钽酸锂（Fe：SLT）晶体．采用二波耦合全息法测量了晶体的记录时间,擦除时间和饱和衍射效率;采用光斑畸变法测量了抗光损伤阈值．与Fe：SLN晶体相比,Fe：SLT晶体的饱和衍射效率降低,记录时间减小,抗光损伤能力显著提高,Fe：SLT晶体的抗光损伤闽值为420MW／cm^2。     

光折变晶体KNbO_3温度效应研究

以光折变效应的带输运模型为基础，研究了高陷阱密度下温度与光折变晶体折射率指数及稳态体相位栅衍射效率之间的关系；分析铌酸钾（ＫＮｂＯ３）晶体的温度特性，给出了相应的Δｎ－Ｔ曲线和η－Ｔ曲线．结果表明，增高光折变晶体的温度，不仅可以增大晶体的折射率指数，同时也是提高稳态体相位栅衍射效率的一条有效途径     

小型光胶合Nd∶YVO_4/PPMgOLN列阵微片绿光激光器

研制出钒酸钇晶体与掺氧化镁(2%)的铌酸锂晶体(Nd∶YVO4/PPMgOLN)光胶合的小型列阵微片绿光激光器.在两点泵浦驱动下,激光二极管(LD)输入总功率为922 mW,腔内倍频下输出532nm的单频绿光功率最高为200mW,光-光转换效率为21.7%.在相同条件下,与单点泵浦激光器进行对比分析,结果表明温度对铌酸锂晶体的倍频效率有很大的影响;由此,通过控制半导体制冷器(TEC),对激光器在两点泵浦驱动下不同温度时的转换效率进行测试,得出当铌酸锂晶体温度在27℃时达到最佳相位匹配.     

LiNbO_3及LiTaO_3晶体的光折变性能研究

光折变效应是电光晶体的一种效应，ＬｉＮｂＯ３及ＬｉＴａＯ３晶体的光折变效应对于该材料的应用具有重要意义，本文从理论和实验两方面研究ＬｉＮｂＯ３及ＬｉＴａＯ３晶体的光析变效应特性，理论分析与实验结果吻合得很好。     

Structure and properties of Li-rich Zn-doped LiNbO3 Crystal

The Li-rich Zn-doped LiNbO3 (LN) crystals were grown by the Czochralski method. The structure of the crystals was measured by ultraviolet-visible absorption spectra. The results indicated that the Li-rich Zn-doped LN crystals had the same characteristics as the pure LN crystal. After Zn2+ entered into the lattice of Li-rich Zn-doped LN crystal, it replaced NbLi firstly. When there was no NbLi, Zn2+ replaced Li+ then. The second harmonic generation (SHG) property of Li-rich Zn-doped LiNbO3 crystal was measured. The results showed that the SHG conversation efficiency of Li-rich Zn-doped LiNbO3 crystals was higher than that of Zn-doped LiNbO3 crystals.     

Investigation of Mechanism of Co-doped Zn2+ and In3+ Influence on Optical Properties of Fe∶LiNbO3

Doping Zn with the concentration of 3mol% and In2O3 with different concentrations in Fe∶LiNbO3, Zn∶In∶Fe∶LiNbO3 crystals were grown.　The infrared spectra of the crystals were measured and the mechanism of the OH-, absorption peak shifting was studied. The diffraction efficiency, response time and photoconduction of the crystals were measured. The mechanisms of the photoconduction increasing, diffraction efficiency decreasing and response time shorting for those crystals were studied.     

Optical Property of LiNbO3 Crystal Codoped with In, Mg and Fe

In2O3, MgO and Fe2O3 were doped in LiNbO3 and Czochralski method was used to grow In:Mg:Fe:LiNbO3 crystals. The OH- extension transmission spectra, light scattering resistance ability, two wave coupled diffraction efficiency and response time of the crystal were measured. Codoping In and Mg in crystal will improve its light scattering resistance ability and response time. Doping In can increase the ability to replace antisite Nb and decrease the doping quantity of Mg. All these are propitious to improve the optical homogeneity of crystal. Doping Fe can improve the photorefractive sensitivity for LiNbO3 crystal. We discussed the site of In, Mg and Fe in LiNbO3 crystals and the influence of the absorption peak of OH- transmission spectra on photorefractive property for LiNbO3 crystal.     

Optical Property of LiNbO3 Crystal Codoped with In, Mg and Fe

In2O3, MgO and Fe2O3 were doped in LiNbO3 and Czochralski method was used to grow In:Mg:Fe:LiNbO3 crystals. The OH- extension transmission spectra, light scattering resistance ability, two wave coupled diffraction efficiency and response time of the crystal were measured. Codoping In and Mg in crystal will improve its light scattering resistance ability and response time. Doping In can increase the ability to replace antisite Nb and decrease the doping quantity of Mg. All these are propitious to improve the optical homogeneity of crystal. Doping Fe can improve the photorefractive sensitivity for LiNbO3 crystal. We discussed the site of In, Mg and Fe in LiNbO3 crystals and the influence of the absorption peak of OH- transmission spectra on photorefractive property for LiNbO3 crystal.     

大直径掺钕铌酸锂晶体生长及其光学性能研究

在LiNbO3多晶料中依次掺入0.2mol%,0.5mol%和1.0mol%的钕,采用我们自主开发的计算机控制直拉法生长大直径Nd:LiNbO3晶体,测试了晶体的紫外-可见吸收光谱、荧光光谱和红外吸收光谱。由紫外-可见吸收光谱确定泵浦光波长,由荧光光谱确定激光振荡波长;采用X射线荧光光谱分析法测量了Nd:LiNbO3晶体中钕的有效分凝系数,结果是Nd:LiNbO3晶体中钕的有效分凝系数随着钕掺杂浓度的增加而减小。     

土壤水分胁迫对银杏无机营养元素含量的影响

应用盆栽土培方法,采用完全随机试验设计,研究了1年生银杏实生苗在土壤水分胁迫下体内矿质营养元素含量的积累及其在各器官中的分配。结果表明:(1)随着土壤水分含量的减少,银杏茎和叶中全氮、叶中全钙和全钾、根中全铜及根、茎和叶中全磷含量有先上升后下降的趋势,而根系中全氮含量变化较少,茎和根中全钙、茎中全铜及茎、根和叶中全镁、全锰和全锌含量逐渐升高,银杏叶中全铜、茎和根中全钾含量逐渐下降;(2)各种土壤水分条件下,全镁、全氮、全磷、全钙等元素含量分配比例在根茎叶中的均表现为在叶中最高,茎中次之,根中最低,全铜含量的分布规律是根中最多茎中次之叶中最少,全锰含量的分布规律表现为根中最多叶中次之茎中最少,全锌含量的分配比例为茎和根中相当,叶中较少,全钾含量在根茎叶中的分配比例因土壤水分条件不同而不同;(3)相关分析表明,所测定的无机营养元素之间,部分表现出显著的正相关或负相关性。     

Growth and Holographic Storage Properties of Fe:LiTaO3 Crystal

Using Si-Mo bar as heater and doping Fe2O3 in LiTaO3, Fe∶LiTaO3 crystal was grown by Czochralski method. The curie temperature of the crystal was measured by thermal analyze method. The lattice constants of the crystal were calculated by measuring of X-ray spectra. The response time, exponential gain coefficient and diffraction efficiency of Fe:LiTaO3 were obtained by two wave coupled technique. Compared with Fe∶LiNbO3, the response time of Fe:LiTaO3 is six times shorter, the storage time of Fe:LiTaO3 is ten times longer and the photo scattering resistance ability of Fe:LiTaO3 is four times higher. Fe:LiTaO3 is an excellent holographic storage material.     

LZ63和LZ113合金板材室温力学性能与显微组织演变

采用熔铸、均匀化、热轧和冷轧方法制备了新型Mg-6Li-3Zn和Mg-11Li-3Zn合金板材.研究了合金的室温力学行为、热轧组织与热轧脱锂现象.两种合金的室温抗拉强度和拉断真应变分别为208MPa,0.13和170 MPa,0.375.真应力-真应变曲线表明Mg-6Li-3Zn合金室温变形发生加工硬化,而Mg-11L...     

Bi-Pb-Sr-Ca-Cu-O超导陶瓷的烧结反应与临界电流密度

用高温X射线衍射、SEM-EDX分析、差热分析和目测法确定了Bi-Pb-Sr-Ca-Cu-O超导陶瓷烧结过程中的中间产物的熔融反应,并考察了这种反应对超导陶瓷显微组织和临界电流密度(J_c)的影响。上述综合研究表明,中间产物[30A相与(Sr_(1-x)Ca_x)_2PbO_4相]的熔融反应产生(Sr_(1-x)Ca_x)_2CuO_3相粗粒,形成成分偏析的显微组织,这是高温反应烧结导致低J_c超导陶瓷的原因。     

Electrochromic effect in domain-inversion process in LiNbO3： Ru： Fe crystals

A reversible electrochromic effect accompanying domain-inversion during the electrical poling process in LiNbO3： Ru： Fe crystals at room temperature has been observed. In electrode area, both electrochromism and domain-inversion occur alternately, and electrochromism is also reversible during back-switch poling, which is experimentally verified and whose mechanism is briefly explained using a microstrncture ferroelectric model. In addition, because of the enhancing elcctrochromic effect, different from the undoped LiNbO3 crystals, the coercive filed （21.0 kV/mm or so） measured in LiNbO3： Ru： Fe is lower than its breakdown field, thus providing a possible new technique for realizing the domain-inversion by constant electric field rather than a pulsed one.