Study The Nonlocal Optical Properties Of Typical Nanostructures

With the development of science and experimental technology, nanostructure materials can be fabricated and have gained interest for strong surface plasmon properties. Especially the surface plasmon properties can reflect the optical characteristics of nanostructures. In the case of external excitation source, surface plasmon polariton(SPP) modes are originated from the resonant excitation of the free electros in the metal-dielectric interface. Plasma optics is a near-field optical enhancement effect, and it is caused by the metal nanostructures conduction electrons interact with electromagnetic radiation. In practical applications such as solar cells, the SPP, simulated by the special optical properties of mental, has made resonance phenomenon, which can greatly improve the efficiency of transmission through changing the thickness of mental films, the surrounding medium and the periodic structure parameters. Its applications are becoming more and more widely in other aspects, such as surface bounded effect and localized near-field enhancement, biosensors, super-resolution imaging and optoelectronic devices in nanoscale.Based on the surface plasmon, the main work is the local and nonlocal properties of different nanostructures. This paper is divided into the following three contents:Firstly, the research background, the concept of surface plasmon and the basic theory of optical properties of nanostructures are introduced.Secondly, the numerical simulation algorithm of noble metal nanostructures is introduced, emphatically the basic principles and methods of the finite difference time domain (FDTD) method algorithm. Also several models of mental dielectric constant are described. By using Drude and Lorentz models to fit the dielectric constant of noble metal. Then the characteristics of the local and nonlocal of mental nanostructures are discussed. Combined with FDTD algorithm, in different dielectric constant models, the concrete difference formula of electric field and magnetic filed are obtained, and by post-processing techniques the absorption cross section, the scattering cross section and extinction section are concluded.Finally, the local and nonlocal properties of different nanostructures is studied. First of all, the transmission, reflection and absorption characteristics of the mental films in different thickness is described. Then, the local and nonlocal properties of different structure of nanowires and cylindrical and triangular nanowire dimmers are discussed. Lastly, the impact on extinction section of the core-shell structure in different size and surrounding medium is studied.