【作者】 谷建强；

【导师】 邢岐荣； 张伟力；

【作者基本信息】 天津大学 ， 光电子技术， 2010， 博士

【摘要】 奇异介质是目前电磁材料研究的重点,由于其具备自然界材料不具备的电磁特性,且其性能人为可控,因此被广泛用于太赫兹波段电磁材料的设计和研究之中。本论文对太赫兹奇异介质进行了详细的研究,具体内容包括:1,介绍了奇异介质的概念和现况,以及太赫兹奇异介质的相关工作,分析了太赫兹波段开展奇异介质研究的优势、挑战和意义。详细阐述了奇异介质工作的相关原理。用RLC等效电路模型分析了SRR阵列LC谐振和四偶极子谐振,用传输线等效电路模型分析了Fishnet负折射率奇异介质。展示了工作中用来对样品进行测量的太赫兹时域光谱系统,和用于制作样品的传统光刻技术。2,研究了方环对太赫兹负折射率奇异介质。工作中,运用自对准光刻技术在Mylar薄膜上制作了方环对奇异介质。利用透射和反射式太赫兹系统对样品进行了测量并反向提取出了奇异介质的等效参数,验证了在0.69 THz处实现了负折射率。最后,用改进的传输线等效电路模型分析了谐振频率与方环几何结构之间的关系,并以不同几何尺寸的样品从实验上验证了模型分析的有效性,为该类奇异介质的研究提供了理论指导。3,研究了基于YBCO的温控太赫兹奇异介质。本工作利用CST模拟设计了SRR的尺寸,并用光刻技术在YBCO薄膜上制作了SRR阵列。低温太赫兹系统的测量结果显示,YBCO奇异介质的LC谐振和四偶极子谐振在临界温度以下有明显的加深。我们用超导体的双流模型对这种温度调控现象进行了解释,基于电导率变化的CST模拟也很好的再现了实验结果。4,研究了光控太赫兹主动式奇异介质。本工作采用了孔阵列与SRR阵列相结合的复合式单元设计,在SOS衬底上用光刻技术与RIE腐蚀制作出奇异介质样品。用光泵太赫兹探测系统对样品进行了测量,观察到了样品受光强控制的反转开关效应。模拟中,泵光光强的变化通过改变SOS上硅层的电导率来体现,模拟结果与实验符合的很好。不同光泵下电场的分布显示反转开关是由SRR的LC谐振与孔阵列的超透射效应交替完成的。更多还原

【Abstract】 Recently, metamaterials play an more and more important role in the research of the electromagnetic components. Because this kind of artificial material has many novel pr operties a bsent i n nor mal m aterials, it i s w idely used i n t he de sign a nd research o f t erahertz components. In t his t hesis w e s tudied s everal t erahertz metamaterials in detail. The main content is listed below:1, F irst w e r eviewed the co ncept and t he d evelopment o f matematerials. The advantages, challenges and significant of terahertz metamaterial were analyzed, too. We utilized the RLC circuit model and the transmission line model to analyze the SRR array and the Fishnet structure, respectively. Several typical terahertz systems were presented as well as the photolithography process of the sample fabrication.2, The first work is the closed-ring pair metamaterial. The sample was fabricated on the Mylar film by a self-aligned photolithography and measured by t ransmission and reflection THz-TDS. The parameters retrieved from the simulation proved the negative refraction index at 0.69 THz. Transmission model was utilized to analyze the influence of t he r ing’s geometry o n t he r esonance, w hich w as a pproved by t he experiments.3, The second work is the YBCO superconducting metamaterial. The SRR based metamaterial was designed by CST and fabricated by photolithography followd by an wet etch in acid. The YBCO metamaterial was investigated experimentally by the cryogenic THz-TDS. Much more pronounced LC and quodrupole resonances were observed w hen t he t emperature was d ecreased b elow t he cr itical t emperature of YBCO. Based on the two-fluid model, the simulation was carried on by changing the conductivity of the YBCO to take account of the change of the temperature, which shows results accordant with the experiments very well.4, The last work is the optical controlled active THz metamterial. In this work a unit cell composed by a rectangular hole and SRRs arrounded was designed. The sample was fabricatied on an SOS wafer by phot olithography and RIE etching. By using optical-pump terahertz-probe system, the optical controlled turn over switch effect of the sample was observed. The simulation is in good accordance with the experminetal results, in which the effect of the optical pump was presented by the conductivity of the silicon film on SOS. The distributions of the electrical filed under various o ptical p ump i ndicated t hat t he switch ef fect ar ises f rom t he ex change between the LC resonance of the SRR and extronamal transmission of the hole array.更多还原