【作者】 聂义然；

【导师】 王彪；

【作者基本信息】 哈尔滨工业大学 ， 工程力学， 2007， 博士

【摘要】 本论文利用中频加热炉,采用提拉法生长In:Zn:LiNbO₃晶体,In:Zn:Fe: LiNbO₃晶体,不同[Li]/[Nb]比的In:LiNbO₃晶体和In:Mn:Fe:LiNbO₃晶体。通过优化晶体生长的工艺参数,生长出无宏观缺陷、光学均匀性好的晶体。通过对晶体进行退火、极化,然后经过加工制备出一系列的试样进行性能测试。对晶体开裂原因进行了分析并提出了有效的解决方案。X射线粉末衍射实验结果表明,In:Zn:LiNbO₃晶体,In:Zn:Fe:LiNbO₃晶体,不同[Li]/[Nb]比的In:LiNbO₃晶体和In:Mn:Fe:LiNbO₃晶体仍然保持纯铌酸锂晶体的晶格结构,但是其晶格常数却发生了不同程度的变化。通过差热分析测试表明,In掺杂LiNbO₃晶体的居里温度随晶体中随着晶体中掺In量或[Li]/[Nb]比的增加先升高后下降。通过研究In掺杂LiNbO₃晶体的光谱性能发现,晶体紫外-可见吸收光谱的吸收边和红外吸收光谱的OH-吸收峰随着掺In量和[Li]/[Nb]比的变化会发生移动。通过分析掺杂离子在晶体中的占位表明,In³⁺首先取代占据锂位的反位铌（ Nb 4L+i）,当In³⁺掺杂浓度达到阈值浓度,即所有的的反位铌（ Nb L4+i）都被取代时,In³⁺才同时取代正常晶格中的Li位和Nb位。利用透射光斑畸变的方法对晶体的抗光折变能力进行了测试,系统地研究了In掺杂和[Li]/[Nb]比变化对晶体的抗光折变性能的影响。实验结果表明,晶体中掺入铟,晶体的抗光折变能力增加,当铟的掺杂量达到阈值浓度后,相应的晶体的抗光折变能力比未掺杂的铌酸锂晶体高大约两个数量级。[Li]/[Nb]比的增大也能对铌酸锂晶体的抗光折变性能起到增强的作用。通过对In:Zn:LiNbO₃晶体的倍频性能测试发现, In（2mol%）:Zn （2mol%）:LiNbO₃晶体的倍频转换效率最高,可达42%。通过对不同[Li]/[Nb]比In:LN晶体的倍频性能测试可以看出,[Li]/[Nb]=1.0的In（1mol%）:LiNbO₃倍频转换效率最高,达到了50%。铟的掺杂和[Li]/[Nb]的增加使得铌酸锂晶体的倍频性能得到了优化。利用退火质子交换法制备了In:Zn:LiNbO₃晶体光波导基片,利用m-线法研究了In:Zn:LiNbO₃晶体光波导基片的光损伤性能,发现在掺In量达到阈值浓度后,波导基片的抗光损伤能力提高了两个数量级以上。通过对In掺杂LiNbO₃晶体的光折变性能进行研究表明,随着铟含量的增加,二波耦合指数增益系数减小,衍射效率降低,动态范围也减小;但是晶体的响应时间缩短,光折变灵敏度提高,通过In掺杂可以有效的调控其光折变综合性能。分析表明In掺杂LiNbO₃晶体中由于有效载流子数目的减少导致其光折变效应减弱,同时由于光电导的提高,使得晶体的响应时间缩短了。将In:Mn:Fe:LiNbO₃晶体用于全息存储系统,实验表明由于In的掺入使得In:Mn:Fe:LiNbO₃晶体存储后的再现相关峰光斑畸变程度变小,光栅建立时间缩短,再现图像的质量高于未掺杂晶体,存储综合性能得到了提高。研究表明通过In的掺杂和[Li]/[Nb]比的改变,使得LiNbO₃晶体的光学性能得到了有效的调节,这将有力的推动LiNbO₃晶体在全息存储领域的实用化。更多还原

【Abstract】 In:Zn:LiNbO₃, In:Zn:Fe:LiNbO₃, In:Mn:Fe:LiNbO₃ crystals with different In2O₃ concentration and In:LiNbO₃ crystals with different [Li]/[Nb] ratios were grown by Czochralski technique using the intermediate frequency furnace as the heater. By selecting appropriate growth technical parameters, crystals with good optical homogeneity and no macroscopic defects have been grown. After the annealing and polarization progress, a series of samples were prepared for measuring the properties. The reasons for the cracking of the LiNbO₃ were discussed and several effective methods were found to conquer it.The structure of the In-doped LiNbO₃ crystals has been measured by X-ray powder diffraction technique. The results indicated that the doped crystals kept the same lattice structure as that of pure LiNbO₃ crystal. But the lattice constants of doped-LiNbO₃ crystals changed compared with pure LiNbO₃ crystal. The Curie temperature of the crystals was measured by differential thermal analysis. The results showed that the Curie temperature increased with the In-doped concentration and [Li]/[Nb] ratio firstly, and then decreased.The infrared absorption spectra and ultraviolet-visible absorption spectra of In-doped LiNbO₃ crystals were measured. The OH- absorption peak of infrared absorption spectra and the absorption edge of ultraviolet-visible absorption spectra shifted with the In-doped concentration and [Li]/[Nb] ratio. The occupy mechanism of the dopants were investingated. The analysis showed that In³⁺ firstly replaced the anti-site Nb ( Nb_Li⁴⁺), which located at Li site. When the In-doped concentration reached the threshold, all the anti-site Nb ( Nb_Li⁴⁺) ions were replaced and In³⁺ began to occupy the ordinary Li and Nb sites.The photo-refractive resistant property was measured by transmitted facula- distoration method. The influence of the In-doped concentration and [Li]/[Nb] ratio on the photo-refractive resistant properties was investigated systematically. The results indicated that the photo-refractive resistant properties improved with the increasing of the In-doped concentration and [Li]/[Nb] ratio. When the In-doped concentration reached the threshold, the photo-refractive resistant ability was two orders of magnitude higher than that of those crystals without In-doped.The second harmonic generation （SHG） propertiesof In:Zn:LiNbO₃ and In:LiNbO₃ with different [Li]/[Nb] ratio were measured and the results indicated that the SHG properties were improved with the In-doped and the increasing of [Li]/[Nb] ratio. The SHG conversation efficiencies of In（2mol%）:Zn（2mol%）:LiNbO₃ and In（1mol%）:LiNbO₃ （[Li]/[Nb]=1.0） were the highest, which were 42% and 50%, respectively. In:Zn:LiNbO₃ optical waveguide substrate were prepared by annealing proton exchange method and the optical damage property of the optical waveguide substrate was investigated by the m-line technique. The optical damage resistant ability was two orders of magnitude higher than that of pure LiNbO₃, when the In-doped concentration reached the threshold.The photo-refractive properties of the In-doped LiNbO₃ crystals were measured. The two-beam coupling exponential gain coefficient, the diffraction efficiency and the dynamic range decreased, while the response time shortened and the photo- refractive sensitivity improved followed by the increasing of the In-doped concentration. The analysis showed that the reduction of the efficient charge carrier density leads to the decreasing of the photo-refractive properties, while the improvement of the photoconduction cause the shortening of the response time.The holographic storage experiment was carried out by using In:Mn:Fe:LiNbO₃ crystal as the storage medium. The results showed that, for the In-doped, the distoration of the coherent peak facula decreased, the establishing time of the optical grating shorted and the quality of the output pictures optimized. The storage properties improved.The research showed that the optical properties of the LiNbO₃ crystal could be improved by doping In ions and changing [Li]/[Nb] ratio. It was helpful for the development of the application of LiNbO₃ crystal.更多还原