摘要：大多数超材料吸收器仅能在特定的一个或是几个频率附近能够达到较高的电磁波吸收率，这极大地影响了吸收器在应用。宽频带的超材料吸收器能够在保持较高吸收效率的同时，还能覆盖一段宽的频带，因此受到研究者的高度关注。本文提出了一种新的超材料吸收器的设计，它在可见光到近紫外频段有良好的宽带吸收效果，同时该结构还具有方向不敏感的特性。本文首先介绍了超材料以及吸收器的相关背景和发展概况，包括超材料的分类、原理、典型设计和研究现状，还有超材料吸收器的发展状况和对宽带吸收器的主要研究成果。然后，提出基于四扇环结构的超材料吸收器的结构设计。第一步展示超材料吸收器优化后的基本结构，并对它的反射、透射和吸收性能进行计算模拟，发现在入射波波长为386.1nm时吸收率接近100%，吸收比率在90%以上的部分涵盖280.4nm到491.8nm的入射波波长范围，相对吸收宽度达到0.548。随后旋转两层四扇环结构，并交换外激发场的位置，以验证该结构对吸收效果的方向不敏感特性。而后模拟讨论扇环形介质层对良好吸收效果的贡献。最后，通过分析吸收器结构内部截面上场强的分布，结合所用材料的特性，揭示吸收器吸收的物理机制。该方向不敏感的宽带超材料吸收器有望在电磁吸收，或是作为光波反射减缓的表面材料等领域发挥重要作用，也可用于紫外线的防护领域。38070
毕业论文关键词：方向不敏感  宽频带  超材料吸收器  光波段
Properties of electromagnetic absorption of a metamaterial based on a four-fan-ring structure
Abstract :Many metamaterial absorbers can only achieve high absorption ratio to electromagnetic wave at one or several specific frequencies, which extremely affects the flexibility of applications in some areas. While, broadband metamaterial absorbers can keep high rate of absorption, and cover a continuous frequency range, simultaneously. This property attracted much attention. In this paper, I present a new design of direction-insensitive metamaterial absorber, and it exhibits near perfect absorption form the visible to ultraviolet range. Here , we firstly introduce the background and development of the metamaterial along with the absorbers, including the classification, theory, typical designs and current researching situation of the metamaterial. We then introduce the development and main achievements of the broadband metamaterial absorbers. Afterwards, we present the design of this metamaterial absorber based on the four-fan-rings structure. Firstly, the optimized structure of this metamaterial absorber is shown, and the reflection, transmission and absorption of the absorber are calculated through simulation. Simulation shows that the absorber exhibits an absorption of nearly unity at the wavelength of 386.1 nm and a relative absorption bandwidth of 0.548, which refers to the ratio of the full absorption bandwidth over an absorption of 90% to the center wavelength. Besides, two four-fan-rings layers were rotated and two external excitation fields were exchanged during the simulation, in order to prove the direction-insensitive property in this structure. We also analyze the well contributions made by the four-fan-rings dielectric layer with simulation. Finally, we analyze the physical mechanism of the high quality absorption of this absorber by plotting the distribution of the fields inside the structure and considering the properties of materials. This direction-insensitive broadband metamaterial absorber has potential applications in electromagnetic absorption and as the cover material to reduce the optical reflection. It can also be used in ultraviolet protection.
Keywords: direction-insensitive  broadband  metamaterial absorber 
optical regime
目录    1
1绪论    2 基于四扇形超材料的电磁吸收特性研究:http://www.751com.cn/wuli/lunwen_36976.html