中文摘要：

本文从理论和实验两方面探讨了具有微结构的金属纳米线系统中表面等离激元传播规律和分光特性．我们由麦克斯韦方程组出发，利用严格耦合波近似和有限元差分等方法首先从理论上给出了金属纳米线系统中等离激元的色散关系和能带特征，然后基于微结构的银纳米线及其等离激元能带结构，设计并制备出等离激元分光原型器件，实验展示其将不同频率的光在微小空间分离的特性．该研究结果是我们前期相关工作的延续和补充，可应用于构造多功能集成的光子芯片和新型亚波长光电材料和器件．

英文摘要：

Due to the coupling of photons with the electrons at a metal-dielectric interface, surface plasmons （SPs） can achieve extremely small wavelengths and highly localized electromagnetic fields. Hence, plas- monics with subwavelength characteristics can break the diffraction limit of light, and thus has aroused great interest for decades. The SP-inspired research, in the application aspect, includes extraordinary optical transmission, surface enhanced Raman spectroscopy, sub-wavelength imaging, electromagnetic in- duced transparency, perfect absorbers, polarization switches, etc.; and in the fundamental aspect, includes plasmon-mediated light-matter interaction, such as plasmonic lasing, plasmon-exciton strong coupling, etc. Recently a series of studies has been performed to push the dimensions of plasmonic devices into deep subwavelength by using nanowires. The chemically synthesized metallic nanowires have good plasmonic properties such as low damping. The reported silver nanowire structures show great potential as plasmonic devices for communication and computation. Now we develop the nanostructured metal wires for plasmonic splitters based on the following considerations. One is that we introduce cascade nano-gratings on a metallic nanowire, enabling a single nanowire to act as a spectral splitting device at subwavelength; and the other is that we use silicon as a substrate for the metallic nanowire, making the plasmonic nanowire device compatible with silicon based technologies. In this paper, we continue and develop our previous work on position-sensitive spectral splitting with a plasmonic nanowire on silicon chip （see Scientific Reports （2013） 3 3095）. The three parts are organized as follows. In the first part, we derive analytically the dispersion relation of the SPs in a suspended silver nanowire based on Maxwell equations. In the second part, we place a silver nanowire in the silicon substrate, and use the finite-element method （FEM） to obtain the dispersion relation of the SPs for the p