【作者】 孙杰；

【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， 2009， 博士

【摘要】 现代通信、电子以及计算机技术的飞速发展离不开光纤通信网络的支持,而光电子技术中的变频、调制、开关、偏转是光信息处理过程中不可缺少的技术。因此,高速电光调制器已经成为光通信网络中不可替代的重要器件。极化聚合物电光调制器由于制备工艺简单、制作成本低、容易实现高带宽等显著优势,近年来倍受到国内外研究人员的重视。本论文的主要工作就是围绕极化聚合物电光调制器的研究展开的。论文重点阐述了利用掺杂型DR1/TiO2/SiO2杂化材料、SU-8紫外负性光刻胶、甲基丙烯酸甲酯共聚物以及铝电极,设计、制备加载条形光波导极化聚合物电光调制器的方法和过程。对器件的材料选择、结构设计、工艺制备以及性能测试进行了详细的论述,并提出了下一步研究工作的展望。本论文的主要创新点为:自主合成了掺杂型DR1/TiO2/SiO2杂化材料,并对材料的成膜特性、吸收特性以及电光特性进行了测试表征。针对合成的材料特点,提出了一种偏振不敏感的加载条形波导结构,利用掺杂型DR1/TiO2/SiO2杂化材料和SU-8紫外负性光刻胶,在国际上首次制备出M-Z结构的基于加载条形光波导的极化聚合物电光调制器。自主设计并搭建了包括光学和电学在内的高速电光器件测试系统,对制备成功的器件性能进行了测试分析。利用波导理论和保角变换原理,首次成功计算了加载条形波导结构和共面波导电极结构的电光重叠积分因子。这些工作为今后制备高指标的电光器件奠定了基础。更多还原

【Abstract】 As the key devices in modern communication network, high-speed electro-optic (EO) modulators play important roles in optical information processing domain. Because of the fast development of information technology and ceaseless pursuing for communication bandwidth, the bandwidth bottleneck of modulator becomes more and more evident. So the demands of high-speed and wide-bandwidth modulators become more and more exigent. Compared with inorganic EO modulators, poled polymer EO modulators show obvious predominance of fast response speed, easy process, low cost, easy integration and wide bandwidth due to the different causation of poling. Much attention is paid on this field.The investigation on poled polymer EO modulators starts in the sixties and seventies in the twentieth century. It developed gradually with the invention of laser. Integrating with modern optics, condensed matter physics, organic chemistry, polymer materials and biological physics, poled polymer EO modulators have obtained huge development in the investigation of new material, design of device structure and application during several decades. By the nineties in the twentieth century, the investigation on poled polymer EO modulators has gained great achievement. The laboratory devices with wide bandwidth and low half-wave voltage have been fabricated. Lots of breakthrough appeared on high speed, wide bandwidth low half-wave voltage and loss. In 2008, commercial poled polymer EO modulators with velocity of 100Gbps and bandwidth of 75GHz have been reported. The performance is much higher than inorganic LiNbO3 EO modulators. But the domestic investigation starts much later. So far, there is hardly any investigation institution that can fabricate and test the poled polymer EO modulators, independently. That is because the fabrication of poled polymer EO modulator with high performance includes the choice and design on EO material, waveguide structure and electrodes configuration. The content refers to materials science, integrated optics, microwave photonics, and so on. The main work of this thesis focuses on the design, fabrication and testing of M-Z poled polymer EO modulators based on strip-loaded waveguide. The content and innovations of this thesis are listed as follows:1. Based on the theories of quantum mechanics, nonlinear optics, quantum chemistry and waveguide mode, the relation between refractive index changes with EO coefficient and electric field is deduced for polymer EO film which is vertically poled. Combining the characteristic of polymer EO film, the principle of M-Z modulator based on polymer waveguide is analyzed. This work lays the theory foundation for structure design and performance testing of EO modulators. 2. The DRl/SiO2 (Disperse Red 1) and DRl/TiO2/SiO2 hybrid material are synthesized by sol-gel technology. The EO film with good poling stability is prepared utilizing spin-coating and corona poling process. The material parameters, such as refractive index, absorption spectrometry and film quality are tested by ellipsometer, infrared spectrum analyzer and atomic force microscopy. The results show that the film is very smooth in surface and has low absorption at 1550nm wavelength. The relation between the proportion of TBOT in the source material and the refractive index or EO coefficient of the film is studied. By adjusting the proportion of TBOT in the source material, the refractive index of the EO film can change from 1.47~1.81. Silane coupling agent (KH-560) and polyvinyl alcohol are added to improve the performance of electro-optic film. The poling uniformity and stability of poled polymer film are studied by testing of the EO coefficient with simple reflective technique. This work lays the foundation for waveguide design and process optimization.3. A strip-loaded waveguide structure is introduced according to the characteristics of the synthesized organic/inorganic hybrid EO materials. Based on the planar waveguide mode theory, the light field modes are simulated and optimized by OptiBPM software. A polarization-insensitive strip-loaded waveguide structure is obtained by adjusting the propagation constant under different polarization. The optimized sizes and refractive indices of the waveguide are as follows: The width and thickness of the strip are 4um and 3.5um. The thickness of the EO layer is 0.4um. The refractive indices of the two layers are 1.57 and 1.68, respectively. The effective refractive indices of TE and TM modes are 1.568 and 1.563. Based on those parameters, the waveguide photo-mask is designed and prepared. Considering waveguide structure and process condition, the microstrip line travelling wave electrodes with 3dB-bandwidth of 105GHz and coplanar waveguide electrodes with 3dB-bandwidth of 15GHz are designed. The electrodes photo-mask is prepared. The electro-optic overlap integral factor of EO modulator with strip-loaded waveguide and coplanar waveguide electrodes is calculated based on planar waveguide mode theory and conformal mapping principle, it is 47%.4. Synthesized hybrid DRl/TiO2/SiO2 hybrid material is chosen as the EO layer. Considering the thermal expansion coefficient and process compatibility, SU-8 epoxy based photoresist and P(MMA-GMA) copolymer are selected as the strip waveguide and up-cladding. Aluminum is utilized as electrode material. By process of spin-coating, photolithography, wet-etching, and corona poling technology, the M-Z poled polymer EO modulator based on strip-loaded waveguide is fabricated for the first time. The modulation function is achieved. The different process conditions to the influence of device parameters are discussed. By reducing the thickness of the strip and enhancing the thickness of the electrodes, the whole performance of the device is improved. The device has a stable state. It can work normally after placed at room temperature for one month.5. The optical and electrical testing system including the tunable laser, fine adjustment testing system, photo detector, optical power meter, functional signal generator, oscilloscope, monitor and vector network analyzer is designed and composed. The successfully-fabricated device is measured. The half-wave voltage is about 50V. The electrode bandwidth is larger than 3GHz. The insertion loss is 14dB. The modulation depth is over 5%. The optical power capacity is larger than 160mW. And the damage voltage is about 110V The polarization characteristic of the device is analyzed. The modulation effect of TM mode is 3 times larger than that of TE mode.In this thesis, the poled polymer EO modulator based on M-Z strip-loaded waveguide is fabricated for the first time. The work established fundamental for the fabrication of high quality electro-optic devices. Some efforts are made to shorten the difference between international and domestic investigation level. With the optimization of material performance, maturity of fabrication process and improvement of test technique, poled polymer EO modulators will highlight the advantages of high speed, wide bandwidth and easy integration. The much more excellent devices will be realized.更多还原