| Surface plasmon polaritons(SPPs) are surface electromagnetic waves, which correspond to a collective oscillation formed by electrons and electromagnetic waves on the metal surface. Because SPPs can exceed the traditional diffraction limit and can produce the effect of local field enhancement, it has showed a wide range of applications in nano-devices, data storage, solar cells, chemical and biological sensors and lots of other areas. Under certain conditions, the light passes through the metallic films perforated by sub-wavelength hole arrays may result in the phenomenon of extraordinary optical transmission(EOT). Since these phenomena have been discovered, they catch much attention around the world. Although there are still many controversies about the physical interpretation of EOT phenomenon, most of researchers believe it is closely related to the quantum resonance of SPPs. In order to further explore and understand the connection between the EOT and SPPs resonance, on the basis of previous researches, several different periodic structures have been studied. By means of the finite difference time domain(FDTD) numerical simulation, we study the electromagnetic field distributions and transmission spectra. And we also make some detailed analysis of the physical mechanisms of EOT. The main contents of this paper include the following three aspects:1) On the basis of periodic slit structure, according to the electric field distribution,rectangular grooves have been embed in the exit surface of the transmission light and transmission characteristics have been researched the by two-dimensional numerical simulation. By changing the size of the groove, the position, as well as the period of structures and other parameters, we study the varying law of the transmission spectra and the electromagnetic field distribution at resonances, and theoretically analyze the causes of the change of maximum transmittance. At the same time, the studies further validate that SPPs resonance plays an important role in the enhanced transmission.2) The phenomenon of EOT of periodic square holes structure that is embedded with grooves has been studied. Compared with periodic slits, this structure which is similar to waveguide has the cutoff wavelength. The transmission spectra of periodic square holes structure with the grooves are compared with the one of periodic square holes structure without the grooves, from which we find that the grooves reduce the transmittance of light waves. Keeping the holes unchanged and changing the grooves length, width, depth, location from the holes, and the polarization direction of the incident light and the period of the structure, we explore the varing characteristics of the transmission spectrum.3) Based on the enhanced transmission of metal periodic structure, we for the first time combine the periodic structure perforated by cylindrical holes with its complementary structure of metal cylindrical arrays. And their transmission characteristics in case of the light at normal incidence have been studied comparatively. Different from the enhanced transmission of the periodic holes, transmission spectrum of the arrays of cylindrical shows a suppressed transmission at some specific wavelength. When changing the radius, thickness and the period of the complementary structures, their transmission spectra will be shifted in the same direction. Moreover, SPPs and localized surface plasmons(LSPs) behave as different roles in different spectra of the complementary structures. Finally, we present a comprehensive research of the transmission characteristics of the hybrid structure that links with the complementary structures. |
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