The Study On Focusing Characteristics Of Metallic Grating

Surface plasmons polaritons (SPPs) are special electromagnetic waves which excited on the boundary surface between the medium and metal, and they are tightly bounded on the metal surface and also propagate on the metal surface in a kind of evanescent wave form. SPPs play a very important role in Nano-Optics because they have the character beyond the diffraction limit. To realize such potentials, ultra-small apertures, such as sub-wavelength holes or slits, are usually utilized to realize the extraordinary optical transmission (EOT) effect and nano-focusing phenomenon based on the sub-wavelength metallic structures.However, the efficiency of the extraordinary optical transmission and nano-focusing proposed by the previous literature is not very high and there is also certain difficulty on the manufacture of these nanoscale structure. In this article, we mainly research the transmission characteristics and nano-focusing on the structure of T-shape slits,the research content is as follows:First of all, under simulating the field distribution of the Metal-Insulator-Metal (MIM) waveguide, we studied the transmission characteristics of periodic T shape slits array, and gave detailed analysis and comparison for the various parameters of the structure, such as we fixed the width of the lower part of the T shape slits and changed the width of the upper part, we also changed the period of the model, as well as the thickness of the metal film. We studied the effect of the transmission characteristics on the main parameters of the periodic nanoscale structure through the simulation calculation for the transmittance of the model.Secondly, we studied nano-focusing characteristics of the structure of single T shape and the structure of tilted T shape on the basis of the work before. We compared the influence of nano-focusing between the structure of single T shape slit and the structure of the inverted T shape slit.Finally, we studied nano-focusing characteristics of the nanoscale slits array. We made the further study of the structure on the convergence effect of the various parameters, also studied the influence of the nano-focusing characteristics after replacing the straight slits array by the T shape slits array.