The Regulation Of Surface Plasmon Polaritons By Micro-nanostructures On Metal Surfaces

Surface plasmon Polaritons (SPPs) is a kind of electron density wave propagating along metal surface formed by the interaction of free electrons on the metal surface and the incident electromagnetic field. The shape, size and arrangement of metal micro-nano structures will cause obvious influence on SPPs, so we can manipulate SPPs on nanostructures by changing factors mentioned above. Because SPPs have many new features, such as enhanced localized electric field, selective absorption of light, the strong restriction of electric field, SPPs have been applied in the field of SPPs waveguide and optical devices integration, surface roughness measurement, optical manipulation, enhanced nonlinear optical properties, and biosensors.In this paper, we designed two micro-nano structures and respectively realized the manipulation for focusing and transmission properties of SPPs. The researches are divided into two main parts:the first part is the focusing of SPPs by non-periodic grooves array on metal surface, the second part is about the effect of the rectangle structure on transmission properties of SPPs on a metallic surface. The main works in this thesis are listed as follows:(1) We designed the structure of non-periodic grooves array satisfied with the phase matching conditions, and studied the function of focusing spot with this structure by using FEM. We studied the effects of width and depth of grooves on the focus spot. Then, we designed the arrays with different excitation wavelength and we got the focus spot at predicted height. Results show that the loss of SPPs in grooves is more with the bigger width. And the more energy is restricted in the grooves and scattering on the side of grooves is more obvious with the bigger depth. Besides, the size of grooves has no effect on the position of predicted spot. Of course, the method is suitable for different excitation wavelength and different predicted height of focus spot. These results are helpful for manipulating beams by using simple metallic grooves array, and could be applied in optical fiber sensing, optical trapping, manipulation and optical integration.(2) We studied the effect of the structure of a metallic interface with a rectangle structure on transmission characteristics of SPPs propagating along the film by using the finite elements method. We studied the effect of the width and height of rectangle, and the separation between rectangle and film on properties of SPPs. And we analyzed the mechanism of transmission troughs and the relation between periods of transmission and two kinds of SPPs. Researches show that SPPs are on the upper surface of rectangle structure and in the separation of rectangle structure and metallic film, thus their interaction affects the transmission characteristics of SPPs. Enhanced electric field due to resonance is around rectangle and the resonator formed by rectangle and film will cause strong localized electric filed. These results have potential application in the field of enhanced nonlinear optics, and they have significant meaning for investigating nanostructure resonator.