Analysis Of Scattering Of Light By The Metal-coated Dielectric Nanocylinders With Cylindrical Periodicity

With the rapidly development of modern photonics and nanoscience, the optical device becomes more adapted to integration and miniaturization. Since nanostructured metal surface plasmons have the localized enhancement effection of local metal and free space at the junction,which can break the diffraction limit of light, they can achieve the control of light transmission.As the optical properties of nano structure are decided not only by the material properties, size and periodical structure but also by the excitation source wavelength, research methods of nano photonics might be distinguished with the general electromagnetism. In this paper, we will focus on the model of the cylindrically periodic arrays of nanowires.Firstly, this paper tends to establish a single-layered cylindrically periodic structure model. It uses the boundary conditions to achieve the connection between the incident field and the scattered field of a single nanocylinder. It can accomplish the calculation of the near field distributions of cylindrical nanowires model in the global coordinate system using Graf's addition theorem, which can be utilized to simulate and analyze the characteristics of the near field distribution and to verify the correctness of the theoretical model as well.In addition, in the research of metal-coated nanowires periodical structure model, the relationship between the metal(Ag) relative dielectric constant and the wavelength of the incident wave can be determined by the method of Drude-Lorentz model. This study selects the appropriate excitation wavelength to observe and analyze the near field distribution characteristics. From the perspective of theoretical derivation of the formula, the cylindrical periodic structure surface plasmon resonance can be attributes to three reasons:(1) the material properties and shape of the single element;(2) the geometrical configuration of multiple elements and the mutual coupling between the elements;(3) the multiple interactions between the layered arrays.We analyze the far field scattering characteristics of the periodic structure by calculating the scattering cross section and the absorption cross section.Finally, based on the study of a single-layer of nanocylinder model, through precise and strict formula calculation, the model of multi-layered metal-coated cylindrically periodic structure can be set up. The study analyzes the characteristics of near field distribution and far-field scattering patterns with two layers of metal- dielectric nanowire system as an example,which can further indicate that the multi-layered periodic structure possess directional properties and conductivity. The results can provide a theoretical basis for the design and manufacturing of optical antenna, solar cells and other optical devices.