【作者】 陆荣国；

【导师】 刘永智；

【作者基本信息】 电子科技大学 ， 光学工程， 2009， 博士

【摘要】 光控相控阵技术是结合微波技术和光电子技术发展起来的一种旨在控制天线阵列波束扫描的现代雷达技术，它实现了微波技术和光电子技术的优势互补。在提升雷达扫描速度、工作频率、瞬时带宽和扫描精度等方面具有其独特的优势，在卫星通讯、射电天文学、航天以及空中管制等领域起着重要作用。集成光学射频(Radio Frequency：RF)移相器是光控相控阵系统中的关键器件，研究它对于精确控制波束的形成、完成预定方位角的波束扫描具有重大意义，因此一直受到广泛的关注和研究。国内对于该器件的研究长期以来处于理论探讨阶段，采用分离器件构建移相器也偶见报道，而国外在这方面已经开始了器件的集成化研究。本文正是基于这一背景而展开研究的。本文提出了一种新型的有机聚合物集成光学RF移相器，对其关键技术进行了研究。结合实验室现有条件进行了如下工作：1．首先简单回顾了有机聚合物材料和光电子器件的发展历史与研究现状，重点介绍了其中的光学RF移相器；然后阐述本论文研究背景及意义，介绍了国内外集成光学RF移相器的研究现状。2．简单介绍聚合物材料的特性和聚合物的电光效应，针对目前有机聚合物集成光学RF移相器存在的移相线性度和功率平坦度问题，提出了一种新型的有机聚合物集成光学RF移相器设计方案，并从理论上证明了该方案能有效解决移相线性度和功率平坦度问题。3．采用变分有效折射率法、有限差分束传播法和微分算子展开束传播法、广角有限差分束传播法分别对有机聚合物脊形波导、M-Z波导和S形波导进行仿真分析，得出了以下结论：(1)当芯层厚度d与脊宽w分别满足d(?)1．5μm，w(?)5μm时，聚合物光波导可以实现单模传输。(2)M-Z光波导优化结构参数为：Y分支角α=1．1°，波导脊宽度w=5μm，双臂间距G=20μm，优化后光的传输损耗为0．258dB。(3)改进后的算子展开束传播法精度高、计算量小、速度快，为光波导的分析和设计提供了可供选择的算法。(4)当S形脊波导曲率半径大于5000μm后，波导的弯曲辐射损耗已不会再明显减小，光能量已可以在S形波导中稳定的传输，形成导模。4．基于全内反射原理，提出一种新型非对称型Y分支，并进行了理论仿真，证明其可以实现特定分束比光输出。5．通过对不同类型电极的比较后选取共面波导行波电极进行研究；用准静态保角变换法来分析共面波导调制器各尺寸参数对调制器特征参量的影响，得出了以下的结论：(1)随着电极厚度增加，有效折射率和特征阻抗都相应的减小。(2)随着聚合物薄膜厚度增加，有效折射率减小，特征阻抗增加。(3)随着电极间距增加，有效折射和特征阻抗都相应的增加。(4)随着电极厚度、聚合物厚度和电极间距中任意一个参量的增加，导体损耗系数都会随之减小。因此在设计时要综合考虑，实现速度匹配和阻抗匹配，从而实现宽带调制。6．对聚合物波导的各个主要工艺步骤进行了实验研究，包括衬底的清洗、下电极的制备、下电极标记的腐蚀、旋涂下包层、光刻、反应离子束刻蚀、电光聚合物的极化、上电极的制备等；制备出了聚合物M-Z波导和非对称型Y分支波导；聚合物极化后电光系数可达50pm／v。7．对聚合物波导的传输损耗、电光系数和折射率的测量方法进行了理论、实验研究。首先基于液体耦合法搭建了聚合物波导传输损耗测量系统；然后对简单反射法测量聚合物宏观线性电光系数的理论进行了详细的推导，并设计搭建了聚合物薄膜电光系数测量系统；最后利用棱镜耦合法对波导样品的折射率进行了测量。8．利用广角有限差分束传播法对光纤和有机聚合物脊形波导的耦合损耗进行了详细的分析，得出了如下结论：(1)耦合损耗随着光纤和有机聚合物脊形波导间的错位、间隙、夹角的增大而增大。(2)因错位而引起的耦合损耗在所有耦合损耗中最大。搭建了耦合实验平台，并对耦合过程中出现的问题进行了分析并给出了解决方案。更多还原

【Abstract】 Optical phased array technology is the modern radar technology that combines both microwave technology and photonics technology for controlling the scanning beam of the antenna arrays. This technology realized the advantage complementary between microwave technology and photonics technology, so it has unique advantages in upgrading radar scanning speed,working frequency,instantaneous bandwidth and scanning accuracy and plays an important role in satellite communications,radio astronomy,space and air control. Integrated Radio Frequency (RP) phase shifter is widely concerned and researched as the key device of controlling beam-forming, as for the domestic research of this device is still in the state of theory, only a separation device constructed phase shifter is occasionally reported, while in the abroad the researcher have already begun the study of integrated devices. Our research is just based on this background. In this dissertation ,we have introduced a new integrated polymer RF phase shifter that shift the phase of RF signal optically. On the base of our laboratory conditions, the dissertation is focused on the key technology in the design and fabrication of integrated polymer RF phase shifter. The main works are as follows:1. The development of organic polymer, the research history and current situation about polymer optical waveguide devices are reviewed,the current situation of integrated RF phase shifter is introduced.2. The theory of electro-optic effect of polymer is investigated. As we all know, the design of the phase shifter suffers from a lack of phase shift linearity and a substantial amount of power variation as the phase is tuned. A new integrated polymer RF phase shifter that shift the phase of RF signal optically is introduced.3. Polymer optical waveguide is an important component in polymer RF phase shifter. The waveguide parameters of the device are optimized by the Variational Effective Index Method, the Finite Difference Beam Propagation Method (FD-BPM), Operator Expansion Beam Propagation Method, and Wide Angle Finite Difference Beam Propagation Method. 4. Based on total internal reflection, a novel asymmetric Y-branch waveguide is proposed in this dissertation, in which the center between the input waveguide and the two branch waveguides is shifted to a small distance A x, and the branching ratio can be controlled by changing A x.5. Another key technology is how to design electrodes structure. The author writes much programme based on the conformal mapping method to simulate electrodes structure of modulators in detail.6. The major processing steps of polymer waveguide are studied. The prototype of polymer M-Z waveguide and asymmetric Y-branch waveguide are obtained. The electro-optic coefficient of polymer after polarization is 50pm/v.7. Waveguide propagation attenuation measuring system is designed based on a refined measurement method - Liquid Coupling Method. A system for measuring the electro-optic coefficient based on the Simple Reflection Method is introduced. A waveguide sample is tested with the Prism Coupling Method and the refractive index is obtained.8. The coupling of fiber and waveguide is a key step of device packaging and it directly affects the inserting loss of the device. In this dissertation, the coupling loss between optical fiber and polymeric rib waveguide are analyzed with Wide Angle Finite Difference Beam Propagation Method and Effective Index Method. The experimental platform is set up.更多还原