Research On Super-resolution Imaging Of Objects Based On Spoof Surface Plasmons

Spoof surface plasmons is an electromagnetic bound states in corrugated surface of perfect conductor. Its plasma frequency is decided by the geometry of the holes and these results open the possibility of engineering a surface plasmon at almost any frequency. Spoof surface plasmons is considered as an important extension of surface plasmons polaritons because its physical properties have strong similarities with the properties of the surface plasmons polaritons bands of a flat metal surface.In this thesis, super-resolution imaging in near field based on spoof surface plasmons of sub-wavelength microstructure arrays have been studied deeply, the work consists of three parts. First, we introduce the theory of spoof surface plasmons in holey metal plate and how such holey metal plate can be used as near field super-resolution super lens. Then, we analyzed the spoof surface plasmons features and near field focus of fractal-like holes drilled in a metal plate by electromagnetic simulation software CST. This structure can be used to realize near field super-resolution imaging at its plasma frequency. In order to design a plasmonic metamaterial with more compact size, we later proposed two kinds of complementary metal structure which can support spoof surface plasmons with lower frequency compared with fractal structure. In the study of their imaging characters, we use a point source and two point sources separated with sub-wavelength distance respectively. The results show that such metal lenses can both achieve near field super-resolution of λ/8.In addition, this article first studied the super-resolution imaging of objects in far field by aid of spoof surface plasmons of sub-wavelength microstructure arrays. In the fourth chapter of this article, a time-reversal process is applied with proposed metal lens to study the far-field super-resolution imaging features via experimental method. Researches show that the sub-wavelength microstructure arrays capable of realizing the conversion of evanescent waves into radiation so that sub-wavelength information can reach the far-field. This is an important basis of far-field super-resolution imaging. In this article, we use metal structures as scatters and put them in the vicinity of two point sources separated with sub-wavelength distance(λ/11). Time-reversal process was used to realize far-field imaging, the experimental results demonstrated that the two structures both have super-resolution focus effect. These researches laid a certain foundation for spoof surface plasmons from theory research to practical application.