| 题名 | 金属纳米结构表面等离激元杂化和吸收特性的研究 |
| 作者 | 梁秋群 |
| 学位类别 | 博士 |
| 答辩日期 | 2015-05 |
| 授予单位 | 中国科学院大学 |
| 导师 | 鱼卫星 |
| 关键词 | 表面等离激元 表面等离激元杂化 超材料 完美吸收体 纳米光刻 |
| 其他题名 | Study on plasmon hybridization and optical absorption properties of metallic nanostructures |
| 学位专业 | 光学 |
| 中文摘要 | 表面等离激元(Surface Plasmons，简称SPs)，是入射电磁波与金属表面的自由电子共振形成的一种表面电磁模。由于其隐失场的特性，SPs能够将光场局域在突破衍射极限的空间范围内，并伴有局域场增强效应。这些特征使得SPs在完美吸收体、纳米光刻、超分辨以及等离激元纳米透镜等领域具有广泛地应用。金属纳米结构里的表面等离激元共振，使得金属纳米结构具有许多独特的光学特性。研究金属纳米结构里的表面等离激元特性，对设计高性能的纳米光子器件具有重要的意义。本论文围绕着表面等离激元杂化、SPs在完美吸收体和在纳米光刻上的应用三个方面进行研究，具体的研究内容和研究成果如下： (1) 在表面等离激元杂化方面，通过电子能量损失谱(EELS)和能量透射电子成像的分析方法(EFTEM)，研究了耦合开口谐振环(SRRs)的表面等离激元杂化问题。采用了有限元与多物理场耦合分析软件Comsol Multiphysics和离散偶极近似的方法，对单个SRR和三个不同开口方向的耦合SRRs的电子能量损失谱(EELS)和能量损失分布图(EELS map)进行了数值模拟；利用了电子束光刻技术制备样品；并利用能量过滤透射电子成像的分析方法获得了能量过滤图，验证了模拟结果。通过比较单个开口谐振环与耦合开口谐振环的电子能量损失谱，可知单个开口谐振环的表面等离激元模式，在耦合开口谐振环中劈裂成了两个新的模式。这是由于开口谐振环里的表面等离激元相互耦合，产生了表面等离激元杂化。此外，在耦合开口谐振环的表面等离激元杂化中，起主要作用的是电偶极矩之间的相互作用。 (2) 在基于表面等离激元的吸收体方面，系统分析了二维金字塔阵列结构的超材料吸收体的吸收特性，利用了有限时域差分法软件FDTD Solutions进行数值模拟，计算了超材料吸收体的吸收光谱以及电磁场分布等，并分析其吸光的机理。数值模拟结果表明，所设计的超材料吸收体在表面等离激元共振、慢光效应和渐变折射率效应共同作用下，实现了对太阳光谱(0.2~2.5 μm)内的光波的完美吸收。改变结构参数，所设计的超材料吸收体同样能够在近红外波段(1~14 μm)获得完美吸收。此外，还分析了表面等离激元复合谐振腔型的红外光子吸收体的吸收特性。此红外光子吸收体通过表面等离激元共振以及法布里-泊罗共振，耦合入射的电磁波，实现了对近红外波段(8~12 μm或其他波段)内的电磁波的强吸收。 (3) 在表面等离激元的纳米光刻技术方面，提出了利用半球形棱镜耦合装置激发传播型表面等离激元进行全息纳米光刻的光刻技术。这种无掩模的光刻技术，可获得高分辨率的干涉图。数值模拟结果表明，通过调整入射光的空间分布以及相对位相分布，可获得由表面等离激元干涉产生的高分辨率二维布拉维晶格点阵图和其他周期点阵图。 |
| 英文摘要 | Surface Plasmons (SPs) are the coherent delocalized electron oscillations that exist at the interface between metal and dielectric medium. Due to the evanescent nature of SPs, light field with localized enhancement is confined at a scale beyond the diffraction limit. These make SPs widely use in perfect absorbers, nanolithography, surper resolution and plasmonic nanolens. Due to the excitation of SPs, there are many unique electromagnetic properties in metallic nanostructures. Investigating the plasmonic properties of metallic structures is very important for designing high performance photonic devices. In this thesis, we focus on the plasmon hybridization, surface plasmons based-perfect absorber, and surface plasmons nanolithography. The main contents and results of the thesis are listed as bellow: (1) In the research field of plasmon hybridization, the plasmon hybridization schemes of coupled split-ring resonators (SRRs) have been studied by combining electron energy loss spectrum (EELS) and energy filter transmission electron microscopy (EFTEM). In order to investigate the plasmonic modes of the isolated SRR, and three different orientations coupled SRRs, Comsol Multiphysics and discrete dipole approximation (DDA) have been used for simulations. In order to proof the simulation results, e-beam lithography has been used to fabricate samples and EFTEM images have been obtained by experiments. By comparing the electron energy loss spectra of the isolated SRR with those of the coupled SRRs, the plasmonic mode of isolated SRR splits into two new modes in the coupled SRRs. This could attribute to the hybridization of the plasmonic modes. Besides, the coupling effects between electric dipole moments dominate the plasmon hybridization in the coupled SRRs. (2) In the research field of surface plasmons based-perfect absorber, a two-dimensional pyramid metamaterial absorber has been proposed. FDTD Solutions has been used to calculate the absorption spectra, the electromagnetic distributions, and to analyze the absorption mechanism. Due to the excitation of SPs, the slow light and the graded-index effects, the proposed metamaterial absorber could obtain near 100% absorption which covers the whole solar spectrum (0.2~2.5μm). By changing the structure parameters, the proposed metamaterial absorber could also obtain near 100% absorption in the infrared range (1~14μm). Besides, a plasmonic hybrid resonator based-infrared absorber has been proposed and analyzed for achieving high absorptivity. Due the plasmonic resonance and the Fabry-Perot (FP) resonance, the proposed absorber could obtain high absorptivity in the infrared range (8~12μm). (3) In the research field of surface plasmons nanolithography. A hemisphereical prism coupling configuration is proposed to excite SPs for the sake of holographic nanolithography. With this method, high resolution patterns could be achieved without using any masks. By adjusting the spatial and the relative phase distributions of the incident light properly, two-dimensional Bravais lattices and other periodic pattens with high resolution could be achieved. |
| 公开日期 | 2015-12-24 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.ciomp.ac.cn/handle/181722/48870]  |
| 专题 | 长春光学精密机械与物理研究所_中科院长春光机所知识产出 |
| 推荐引用方式 GB/T 7714 | 梁秋群. 金属纳米结构表面等离激元杂化和吸收特性的研究[D]. 中国科学院大学. 2015. |
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