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题名:
基于坐标变换理论的电磁超材料结构研究及设计
作者: 王卫
学位类别: 博士
答辩日期: 2009-06-03
授予单位: 中国科学院光电技术研究所
授予地点: 光电技术研究所
导师: 罗先刚
关键词: 变换光学 ; 坐标变换理论 ; 超材料 ; 电磁和光学器件 ; 超分辨成像 ; 完美透镜 ; hyperlens ; 电磁聚能结构
其他题名: Investigation and design of metamaterial-related electronmagnetic devices based on coordinate transformation theory
学位专业: 光学
中文摘要: 近年来,基于坐标变换理论的“变换光学”的迅速发展已经使其成为设计复杂电磁材料结构的一种简单实用的方法。基于这种变换理论,具有独特光学和电磁特性的各种电磁和光学器件也被不断提出和设计。利用这些新型器件能够让电磁波按照设计的路径传播,从而实现对电磁波的控制。变换光学已经广泛应用于电磁隐形、超分辨成像系统等方面的设计之中。同时,超材料(Metamaterials)的迅速发展也为这些新型器件的设计与实现提供了可能性。本文工作主要包括: 1. 利用坐标变换理论,设计了具有特定功能的成像结构。首先是具有放大作用的椭圆柱“完美透镜(Perfect lens)”,能够将物点信息“完美”地从物面放大到像面,实现超分辨成像。该透镜的主要特点在于其物面为平面,方便了测试物体的放置、观察和探测。对各种形状的完美透镜进行了系统的有限元仿真,详细讨论了椭圆柱完美透镜的放大成像特性,同时仿真验证了平板完美透镜不具有放大成像的功能,也验证了坐标变换理论设计超分辨成像系统的可行性。 2. 利用椭圆柱坐标系,结合另外一种正交曲线坐标系,设计了平板放大hyperlens。然后用金属加介质的多层薄膜超材料设计了具有平面到平面超分辨放大成像作用的“hyperlens”成像系统,该系统具有物面和像面均为平面的特点,方便光源的放置和像的探测。我们针对该hyperlens做了有限元仿真,在光频段(365nm)实现了1/5波长分辨率。同时详细分析了结构参数对分辨率和放大率的影响。 3. 文中还针对基于坐标变换理论的电磁聚能结构(Concentrator),分析了其聚能效果和散射特性,设计了具有简化物质参数的聚能结构,减少了由于边界阻抗不匹配带来的散射损耗,从而在简化了物质参数、降低了实际应用难度的同时提高了聚能结构的聚能效率。最后用有限元法仿真了具有各种不同简化物质参数的聚能结构的聚能特性,进一步验证了理论分析的正确性。 4. 用贝塞尔函数展开法详细分析了理想物质参数下电磁聚能结构和电磁波相互作用的过程,并分析了其散射特性和聚能效果,定量给出了中心聚能的能量密度和聚能结构几何参数之间的严格的依赖关系,定性给出了理想物质参数聚能结构的聚能的物理机制和聚能特性。同时用有限元法系统仿真了各种几何参数下的聚能效果,验证了理论分析的正确性,为其将来的实现和应用提供了理论基础。
英文摘要: The transformation optics based on coordinate transformation theory has recently been extensively applied to design novel electromagnetic and optical devices. Many devices have been proposed and realized based on this theory as a new method of guiding and controlling electromagnetic waves or lights to behave as we desire. Now this new theory has been extensively applied to many fields, such as invisibility cloaks and sub-wavelength imaging systems. The development of metamaterials also provides possibilities of realizing these devices. This thesis includes the following four parts: 1. Based on the coordinate transformation theory, we designed an oblate cylindrical perfect lens, which is capable of “perfectly” magnifying an object from the object surface to the imaging surface, obtaining a “perfect” image far beyond the diffraction limit. The feature of this designed perfect lens is its planar imaging surface, which greatly facilitates the observation and measurement of images at the imaging plane. Then we performed finite-element simulations on “perfect lens” with various kinds of geometry, systematically analyzed their imaging properties and functionality. 2. By using the oblate cylindrical system and combining another orthogonal curvilinear coordinate system, we designed a planar magnifying hyperlens. The object surface and the imaging surface of the hyperlens were designed to be planar, which is expected to be useful in the placing the objects as well as in the measurement of the images. We also proposed a kind of metamaterial containing multi-layer metal and dielectric medium as a possible approach to realizing this imaging system. The finite-element method was used to simulate the designed hyperlens and a sub-wavelength resultion of was obtained. The dependence of magnifying property of the hyperlens on the structural parameters was also analyzed. 3. We analyzed the concentrating and scattering property of another novel coordinate-transformation-based electromagnetic device called concentrator. For the ease of future realization, we further proposed concentrators with reduced material parameters, which greatly reduce the engery loss caused by the mismatch at the interfaces of the inner and outer boundaries. Simulations were also performed on these proposed devices. This kind of concentrator with simpler material parameters and higher concentrating efficiency is expected more feasible for the future experimental realization. 4. We investigate the concentrating capability of the concentrator with ideal material parameters by using Bessel function expansion of the incident EM waves. The exact dependence relation of the concentrating property on the structural feature of the concentrator is obtained. The mechanism behind concentrating property is quantitatively summarized. 2D finite element simulations are performed for the concentrators with different structural parameter to confirm our theoretical analysis.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ioe.ac.cn/handle/181551/336
Appears in Collections:光电技术研究所博硕士论文_学位论文

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Recommended Citation:
王卫. 基于坐标变换理论的电磁超材料结构研究及设计[D]. 光电技术研究所. 中国科学院光电技术研究所. 2009.
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