摘要：实时动态全息3D显示是一种新型显示技术，已成为国际研究热点之一。铌酸锂晶体（LN）是一种可用于全息显示的光折变材料，但响应速度慢限制了其实现实时动态全息3D显示。采用适当的极化方式能有效提高LN的光折变响应速度，但其机理尚不明确。相对于掺杂LN，以纯LN为研究对象，更有利于弄清极化与快响应之间的关系。故本文以纯LN为研究对象，采用提拉法生长了晶体，极化晶体的电流强度分别为15mA、40mA、70mA和100mA。XRD测试结果表明固相烧结法制备的纯LN多晶料为LN纯相，具有较高的质量。LN晶体的双摇摆曲线结果为峰的半高宽均较窄，处于10″-18″范围，表明晶体有较好的结晶质量。在473nm处的光折变性能测试结果表明，LN的饱和衍射效率和响应速度分别随着极化电流的增加而提高，尤其是当极化电流为100mA时，有最快的响应速度3.4s并且饱和衍射效率为3%。擦出曲线拟合结果显示双中心模型更适合极化后的LN。双波耦合测试结果表明当晶体内部发生光折变时，载流子以扩散的形式进行迁移，且主导载流子为电子。

关键词：实时动态全息3D显示；极化；铌酸锂晶体；响应速度

Study on the Effect of Polarization Conditions on Optical Properties of Pure Lithium Niobate Crystals

Abstract: Real time dynamic holographic 3D display is a new display technology and it has become a hot project all over the world. Lithium niobate crystal (LN) is a kind of photorefractive material which can be applied to holographic display. However, the slow response speed limits its real-time dynamic holographic 3D display. The proper polarization method can improve the photorefractive response speed of LN effectively, but the mechanism is not clear. Compared with doped LN, using pure LN as the research object is more conducive to clarify the relationship between polarization and fast response. Therefore, we used pure LN as the research object. The crystals were grown by the Czochralski method. The current densities of the polarized crystals were 15 mA, 40 mA, 70 mA, and 100 mA, respectively. The XRD results show that the pure LN polycrystalline material made by the solid phase sintering method is of LN pure phase with high qualities. The double rocking curve of the LN crystal shows that the full width at half maximum of the peak is in the range of 10″-18″, indicating that the crystal has good crystal qualities. The photorefractive performance results tested at 473nm show that the saturation diffraction efficiency and response speed of LN increase with the increasing of polarization current, especially when the polarization current is 100mA, the fastest response speed is 3.4s and the saturation diffraction efficiency is 3%. Erasing curve fitting results show that two-center model is more suitable for polarized LN. The two-wave coupling test results show that when photorefractive occurs inside the crystal, carriers migrate in the form of diffusion and the dominant carriers are electrons.

Key Words: Real time dynamic holographic 3D display; Polarization; Lithium Niobate Crystals; Response speed

目录

1.绪论 1

1.1实时动态全息3D显示的简介及发展 1

1.2实时动态全息3D显示用有机光折变材料的研究进展 2

1.3铌酸锂晶体简介与研究进展 5

1.3.1铌酸锂晶体简介 5

1.3.2铌酸锂晶体的研究进展 5

1.4铌酸锂晶体生长方法简介 8

1.4.1坩埚下降法简介 8

1.4.2提拉法简介 9

1.5研究内容 11

2.实验部分 12

2.1实验原料 12

2.2实验仪器和设备 13

2.3晶体生长 13

2.3.1生长工艺 13

2.3.2晶体极化 14

2.4晶体加工 15

2.4.1晶体切割 15

2.4.2晶体抛光 16

2.5晶体性能表征 17

2.5.1多晶料分析 17

2.5.2晶体结晶质量测试 17

2.5.3光折变性能测试 18

2.5.4紫外-可见透射光谱 19