表面等离子体纳米结构.doc
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表面等离子体纳米结构,摘要表面等离子体的发现及应用，为实现纳米尺度的光学控制提供了有力的工具。金属纳米粒子对表面等离子体的研究至关重要，选择合适形状、尺寸以及排列结构的纳米粒子结构，可以提高表面等离子体的光场强度，更好地实现基于纳米粒子阵列的表面等离子体的聚焦和导波。本文主要研究了金膜上纳米粒子抛物链在外电场激励下的表面等离子体的聚焦和导波...
内容介绍
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摘 要
表面等离子体的发现及应用，为实现纳米尺度的光学控制提供了有力的工具。金属纳米粒子对表面等离子体的研究至关重要，选择合适形状、尺寸以及排列结构的纳米粒子结构，可以提高表面等离子体的光场强度，更好地实现基于纳米粒子阵列的表面等离子体的聚焦和导波。
本文主要研究了金膜上纳米粒子抛物链在外电场激励下的表面等离子体的聚焦和导波：
（1）针对格林函数分量计算中涉及到的Sommerfeld积分，研究了快速算法实现高效的积分运算，给出了沿最陡下降路径积分的计算实例，并与国外的结果进行分析对比，证明了运用的计算方法结果正确，算法快。基于Sommerfeld积分的快速算法，分析和计算了半空间中任意方向的电偶极子的辐射和散射。
（2）从电磁基本理论出发，深入研究了金膜上基于纳米粒子抛物链的表面等离子体的相互作用，由并矢格林函数求解波动方程，建立分层参考系统的电磁场模型。将纳米粒子抛物链划分为一系列立方单元，并利用耦合偶极子法将该积分方程转化为矩阵方程，从而计算出空间任意点的电场。
（3）应用格林函数体积积分法，研究了金膜上球形纳米粒子链在高斯光束照射下的SPPs激发、聚焦和导波。研究了入射光斑大小、入射光沿链的位置、粒子间距和粒子链的曲率半径对SPPs激发、聚焦和导波影响。结果表明，粒子间距、入射光斑大小对SPPs聚焦及其分布有很大影响。入射光斑尺寸减小，激发的SPPs光束的衍射发散的增加，SPPs聚焦效果减弱。SPPs场在很大程度上也取决于粒子间距，在粒子间距小于SPPs波长时，可以实现较好的SPPs聚焦和导波效果。
关键词 表面等离子体；纳米粒子；格林函数法；耦合偶极子法；数值模拟
Abstract
Surface plasmon polaritons (SPPs) have been proved to better powerful tool for the optical manipulation on nanoscale. The nanoparticle on the metal thin film plays an important role of surface plasmon polaritons. If the metallic nanoparticles are designed with suitable shape, size and arrangement, electric field magnitude can be highly improved. Further, excitation, focusing and directing of surface plasmon polaritons with nanoparticles located on a finite metal layer could be accomplished theoretically.
No matter which method is used for the calculation of scattered fields, there will be a common difficulty: the eva luation of Sommerfeld integrals, which is extremely time consuming. The integration along steepest descent paths is introduced to eva luate these Sommerfeld integrals. Numerical results show that the fast method can greatly accelerate the computation for scattering problems. Based on the fast eva luation of Sommerfeld integrals, the radiation of an arbitrarily oriented electric dipole in a half space is first analyzed and computed.
Excitation, focusing and directing of surface plasmon polaritons with curved chains of nanoparticles located on a finite gold layer are investigated theoretically. The theory of Green’s dyadic functions on a layered reference system is outlined and electromagnetic properties of surface plasmons are discussed. A curved chain of nanoparticles in upper half-space is divided into a number of cubic cells and the integral equation is reduced to a matrix equation using coupled dipole formalism. Then we calculate the electric fields at any point on gold surface.
Numerical simulations of the configuration investigated experimentally are carried out based on the Green’s tensor formalism and dipole approximation. We demonstrate that, by using a relatively narrow Gaussian beam (at normal incidence) interacting only with a portion of a curved chain of nanoparticles, one can excite an SPP beam whose divergence and propagation direction are dictated by the incident light spot size and its position along the chain. It is also found that the SPPs focusing regime is strongly influenced by the chain inter-particle distance. Comparison of numerical results with experimental data shows good agreement with respect to the observed features in SPPs focusing and directing, providing the guidelines for a proper choice of the system parameters.
Keywords surface plasmon polaritons (SPPs); nanoparticles; Green’s dyadic function; coupled dipole formalism; numerical modeling
目 录
摘要 I
Abstract III
第1章 绪论 1
1.1表面等离子体的研究背景 1
1.2表面等离子体的研究现状和应用 1
1.3表面等离子体的研究目的与意义 5
1.4本文研究的内容 6
第2章 金属结构的表面等离子体 8
2.1表面等离子体与金属纳米材料 8
2.2金属块状材料的光学性质 8
2.3 表面等离子体的基本原理 11
2.3.1 SPPs色散关系 11
2.3.2 SPPs特征长度 14
2.3.3 SPPs的激发方式 17
2.4 金属纳米粒子的局域化表面等离激元 19
2.5 本章小结 21
第3章 数值方法 22
3.1 数值方法的概述 22
3.1.1矩量法 22
3.1.2有限元法 23
3.1.3 时域有限差分法 23
3.1.4 格林函数法 24
3.2并矢格林函数 24
3.2.1 并矢的定义 25
3.2.2 并矢格林函数的空间表示 26
3.2.3 并矢格林函数奇异性的处理 29
3.3格林函数分量计算 31
3.3.1任意方向偶极子的电场计算 31
3.3.2 Sommerfeld积分的快速计算 34
3.3.3辐射和散射数值结果 37
3.4本章小结 39
第4章 基于纳米粒子链的表面等离子体的研究 40
4.1基于纳米粒子链的SPP..
表面等离子体的发现及应用，为实现纳米尺度的光学控制提供了有力的工具。金属纳米粒子对表面等离子体的研究至关重要，选择合适形状、尺寸以及排列结构的纳米粒子结构，可以提高表面等离子体的光场强度，更好地实现基于纳米粒子阵列的表面等离子体的聚焦和导波。
本文主要研究了金膜上纳米粒子抛物链在外电场激励下的表面等离子体的聚焦和导波：
（1）针对格林函数分量计算中涉及到的Sommerfeld积分，研究了快速算法实现高效的积分运算，给出了沿最陡下降路径积分的计算实例，并与国外的结果进行分析对比，证明了运用的计算方法结果正确，算法快。基于Sommerfeld积分的快速算法，分析和计算了半空间中任意方向的电偶极子的辐射和散射。
（2）从电磁基本理论出发，深入研究了金膜上基于纳米粒子抛物链的表面等离子体的相互作用，由并矢格林函数求解波动方程，建立分层参考系统的电磁场模型。将纳米粒子抛物链划分为一系列立方单元，并利用耦合偶极子法将该积分方程转化为矩阵方程，从而计算出空间任意点的电场。
（3）应用格林函数体积积分法，研究了金膜上球形纳米粒子链在高斯光束照射下的SPPs激发、聚焦和导波。研究了入射光斑大小、入射光沿链的位置、粒子间距和粒子链的曲率半径对SPPs激发、聚焦和导波影响。结果表明，粒子间距、入射光斑大小对SPPs聚焦及其分布有很大影响。入射光斑尺寸减小，激发的SPPs光束的衍射发散的增加，SPPs聚焦效果减弱。SPPs场在很大程度上也取决于粒子间距，在粒子间距小于SPPs波长时，可以实现较好的SPPs聚焦和导波效果。
关键词 表面等离子体；纳米粒子；格林函数法；耦合偶极子法；数值模拟
Abstract
Surface plasmon polaritons (SPPs) have been proved to better powerful tool for the optical manipulation on nanoscale. The nanoparticle on the metal thin film plays an important role of surface plasmon polaritons. If the metallic nanoparticles are designed with suitable shape, size and arrangement, electric field magnitude can be highly improved. Further, excitation, focusing and directing of surface plasmon polaritons with nanoparticles located on a finite metal layer could be accomplished theoretically.
No matter which method is used for the calculation of scattered fields, there will be a common difficulty: the eva luation of Sommerfeld integrals, which is extremely time consuming. The integration along steepest descent paths is introduced to eva luate these Sommerfeld integrals. Numerical results show that the fast method can greatly accelerate the computation for scattering problems. Based on the fast eva luation of Sommerfeld integrals, the radiation of an arbitrarily oriented electric dipole in a half space is first analyzed and computed.
Excitation, focusing and directing of surface plasmon polaritons with curved chains of nanoparticles located on a finite gold layer are investigated theoretically. The theory of Green’s dyadic functions on a layered reference system is outlined and electromagnetic properties of surface plasmons are discussed. A curved chain of nanoparticles in upper half-space is divided into a number of cubic cells and the integral equation is reduced to a matrix equation using coupled dipole formalism. Then we calculate the electric fields at any point on gold surface.
Numerical simulations of the configuration investigated experimentally are carried out based on the Green’s tensor formalism and dipole approximation. We demonstrate that, by using a relatively narrow Gaussian beam (at normal incidence) interacting only with a portion of a curved chain of nanoparticles, one can excite an SPP beam whose divergence and propagation direction are dictated by the incident light spot size and its position along the chain. It is also found that the SPPs focusing regime is strongly influenced by the chain inter-particle distance. Comparison of numerical results with experimental data shows good agreement with respect to the observed features in SPPs focusing and directing, providing the guidelines for a proper choice of the system parameters.
Keywords surface plasmon polaritons (SPPs); nanoparticles; Green’s dyadic function; coupled dipole formalism; numerical modeling
目 录
摘要 I
Abstract III
第1章 绪论 1
1.1表面等离子体的研究背景 1
1.2表面等离子体的研究现状和应用 1
1.3表面等离子体的研究目的与意义 5
1.4本文研究的内容 6
第2章 金属结构的表面等离子体 8
2.1表面等离子体与金属纳米材料 8
2.2金属块状材料的光学性质 8
2.3 表面等离子体的基本原理 11
2.3.1 SPPs色散关系 11
2.3.2 SPPs特征长度 14
2.3.3 SPPs的激发方式 17
2.4 金属纳米粒子的局域化表面等离激元 19
2.5 本章小结 21
第3章 数值方法 22
3.1 数值方法的概述 22
3.1.1矩量法 22
3.1.2有限元法 23
3.1.3 时域有限差分法 23
3.1.4 格林函数法 24
3.2并矢格林函数 24
3.2.1 并矢的定义 25
3.2.2 并矢格林函数的空间表示 26
3.2.3 并矢格林函数奇异性的处理 29
3.3格林函数分量计算 31
3.3.1任意方向偶极子的电场计算 31
3.3.2 Sommerfeld积分的快速计算 34
3.3.3辐射和散射数值结果 37
3.4本章小结 39
第4章 基于纳米粒子链的表面等离子体的研究 40
4.1基于纳米粒子链的SPP..
