Design And Transmission Characteristics Analysis Of Rectangular Huygens' Metasurfaces

With the development of optical research,people have been trying to use a variety of technical means to achieve the effective control of the amplitude,phase and polarization of light.Metamaterials and metasurfaces may have unique properties different from those of natural materials,thus providing new methods for optical manipulation.Based on Huygens' basic principle,the Huygens' metasurfaces form the equivalent Huygens' sources by designing unit structures,which is considered to be able to realize the complete control of the amplitude,phase and polarization of light in theory,and they have attracted much attention.In this paper,the phase control of light is realized by using Huygens' metasurface in terahertz band.At present,the researches on Huygens metasurfaces mainly focus on the realization of phase modulation function,such as anomalous refraction or reflection.The existing Huygens metasurfaces design usually have high transmission efficiency.However,they also have complex unit structure design,which increases the manufacturing difficulty and makes it difficult to scale to higher frequencies.Huygens metasurfaces made of nonmetallic materials have high efficiency and higher requirements for process.Therefore,based on the above problems,this paper designs a two-layer metal structure with a simpler design.In this thesis,according to the simulation results,we analyzed the mechanism by which the double-layer metal sheet structure can realize the Huygens source.Furthermore,the loss of the structures we designed is further revealed by simulation,which comes from metal ohmic loss and dielectric loss,respectively.By adjusting the structural parameters,the double-layer metal sheet structure we designed can achieve complete 2? phase control of transmitted light by changing a single structural parameter without the need for other complicated designs.And the double-layer metal sheet design has a simple model structure,which is more conducive to physical implementation.We designed a set of metasurfaces to implement the anomalous refraction function.Simulation results show that the metasurface of the double-layer metal sheet structure can achieve an anomalous refraction with a deflection angle of 19.8 degrees,and an anomalous refraction efficiency of 66%.In order to make the metasurfaces with diverse functions,we successfully improved the design of three-layer metal sheet on the basis of double-layer metal structure design.By changing two structural parameters,complete 2? phase control of transmitted light can be achieved,and it can also be used to achieve phase control of reflected light.With reasonable design,we designed two sets of metasurfaces.One group can achieve an anomalous refraction with a deflection angle of 27.6 degrees and an anomalous refraction efficiency of 62%.The other group is designed as an anomalous reflection metasurface,which can achieve an anomalous reflection with a deflection angle of 27.6 degrees and an anomalous reflection efficiency of 60%.