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极化聚合物薄膜的电光特性研究

Basic Research on Electro-Optic Characteristics of Poled Polymer Thin Films

【作者】 王希斌

【导师】 张大明;

【作者基本信息】 吉林大学 , 微电子学与固体电子学, 2010, 硕士

【摘要】 极化聚合物材料由于其优良的可加工性,高度的可剪裁性和优异的衬底兼容性等优点,以及近年来在光损耗、热稳定性等关键特性方面的突破性进展,使得极化聚合物电光材料在高速电光器件方面有着重要的应用前景。本论文针对制备高速电光调制器、电光开关的极化聚合物电光材料在理论和实验上进行了基础性的研究工作。搭建并校准了测量极化聚合物薄膜电光系数的简单反射法测试系统,首次提出在高频段测量电光系数的准确性。针对单层电光材料和有上包层的电光材料,分别推导了计算其电光系数的公式。另外,为了消除系统带来的误差,还推导了计算GaAs电光系数的公式,利用两式作比得到了校准后的计算极化聚合物电光系数的公式。利用简单反射法测试系统测量了极化聚合物DR1/PMMA在1310nm波长下的电光系数为11.45pm/V,理论和实验结果表明,用校准后的反射法测试系统测得的电光系数具有更高的可靠性。首次用溶胶—凝胶法制备了? -(2,3-环氧丙氧)丙基三甲氧基硅烷(KH560)修饰的掺杂型DR1/SiO2—TiO2有机/无机杂化电光材料,利用校准后的测试系统在1310nm波长下测得其电光系数为3.5pm/V。有机相的引入解决了以往有机/无机杂化材料薄膜易开裂的问题,针对这种材料柔韧的特性,设计并制备了上加载条形电光波导,最后得到了这种结构波导的近场输出光斑。

【Abstract】 Recently, with the rapid development of high-speed optical communication and all-optical networks, the higher requirements for optical communication devices and photonic integrated has been put forward. And the study of poled polymer materials has also been promoted greatly. The inorganic materials ,which are currently used, such as LiNbO3, III-V compound semiconductor materials(GaAs/GaAlAs、InGaAsP/InGaAs), silicon-based semiconductor materials(Si、SOI、SiO2), are difficult to meet the key requirments of high-speed, large capacity, wide-bandwidth, high-density for the actual system. In contrast, poled polymer materials have rised a wide concern of scientific researchers and businessmen because of their fast response speed, large electro-optic (E-O) coefficient, low dielectric constant, easy process and so on. Therefore, the study to the poled polymer is extremly valuable for research and applications on a wide range.Currently, the research on the poled polymers is mostly concentrated in their preparation, poling, and E-O testing. For different polymer systems, the methods of their preparations are also different, for example, the organic / inorganic hybrid E-O material which now attracts most attention is based on Sol-Gel method, while the host and guest doped E-O materials are just simple physical doping. As to the poling method of polymers, it has been developed from electrode-contact poling at first, to today’s corona poling, all-optical poling, and auxiliary poling of light. The corona poling and contact poling are the two most widely used poling techniques. In the E-O testing, the focus is on measuring the E-O coefficient of the poled polymers. In recent years, there have been many ways for measuring the E-O coefficient of the poled polymers, such as Mach-Zehnder interferometer method, waveguide technology based on Fabry-Perot cavity method (F-P resonant cavity method), attenuated total reflection(ATR) method, secondary harmonic generation method (SHG method), and the simple reflection method. Compared with other methods, the simple reflection method is becoming a widely used measuring methods because it can be achieved more quickly and easily. Thus, the research on the test system and calculating method is particularly important. Firstly,the concept, main advantages and classification of poled polymer are introduced in this thesis. Secondly, the E-O effect of poled polymer is studyed, the method to enhance the E-O coefficient, and the principle and techniques of polarization. Then, the basic research focused on setting up and adjustment of the simple reflection system for measuring the E-O coefficient is carried out. And the formula for measuring the E-O coefficient of poled polymer is also deriveded and adjusted. Finaly, a kind of organic/inorganic hybrid E-O material via sol-gel method is analyzed by both theory and experiment. And the waveguide based on this material is fabricated and measured successfully. The main results are listed as follows:1. The simple reflection system for measuring the E-O coefficient of poled polymer is set up, and the calibration is placed on this system based on its principle. Then, we derived the formula of calculating the E-O coefficient for the single layer E-O material and the GaAs. Because of the error resulted from the testing system, we derived a adjusted formula for calculating the E-O coefficient of single layer E-O material.2. The formula is derived for calculating the E-O coefficient of two-layer film which contains one layer top caldding on the E-O film. And according to optical configuration of the laser beam propagation in this structure, the influence of impedance and dielectric constant of the top cladding at the AC modulated voltage is analysed, which is important for designing E-O devices such as E-O modulation, E-O switch and so on.3. With the testing system, we measure the E-O coefficient of poled polymer DR1/PMMA, and obtain stronger signals at the frequency of 30KHz and 50KHz. The accuracy for measuring E-O coefficient in the high-frequency is demonstrated. And we measure E-O signals in different frequencies at the range of 70KHz to 130KHz, and the EO coefficient is about 11.45pm/V at 1310 nm wavelengh which is measured by our system and formula adjusted. Thus, it proves that the testing system and the formula adjusted for calculating the E-O coefficient of the poled polymer materials are accordant.4. We synthesize a kind of silane coupling agent KH560-based organic / inorganic hybrid E-O material by Sol - Gel method. The reaction mechanism of hydrolysis and condensation of KH560 in the case of hydrochloric acid as a catalyst is analysed. Then we characterize the surface morphology, refractive index and E-O properties of the E-O thin films by means of atomic force microscopy (AFM), ellipsometry, and simple reflection method. At last, we obtain the poled polymer films that have good shape and alterable refractive index. The electro-optic coefficient is measured to be 3.5pm / V at the wavelength of 1310nm wavelengh based on the simple reflection method.5. By utilizing silane coupling agent KH560 as the silicon source, we successfully enhance the the flexibility of organic/inorganic hybrid E-O materials. According to the feature, we design the structure of the strip-loaded waveguide guided by the simulating results of the two-dimensional and three-dimensional light fields by the Opti-BPM software. After exploring the processing technology, we complete the fabrication of the waveguide with strip-loaded structure. Finally the near-field images of this waveguide are obtained by through the measurment system.

  • 【网络出版投稿人】 吉林大学
  • 【网络出版年期】2010年 09期
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