The Researches On Polarization Characteristics And Applications Of Metamaterials With Chirality Or Anisotropy

In recent years,the rapid development of metamaterials in electromagnetic manipulation has shown great potential for application.Before,the most conventional methods available accomplished by natural material for electromagnetic controlling have a lot of deficiency,such as low efficiency and big bulk,which hinder its development and applications in the relevant field.While metamaterials are becoming a better choice for new devices due to performing more unique properties and overcoming the shortcoming brought by traditional device by adjusting structure and geometrical size.Based on the metamaterials theory and numerical simulation method,we have investigated the relevant reflective characteristics and polarization properties of the metamaterials,including chiral metamaterials and anisotropic metamaterials.The research contents can be concluded as follows:(1)A terahertz polarization convertor device based on the chiral metamaterials has been proposed and investigated theoretically.By the asymmetric combination of plasmonic grating and split-ring the incident linear polarization can be transformed.It is investigated that broadband(0.28~1.82THz)high efficient polarization conversion ratio(PCR higher than 0.9)can be achieved by CST MWS.Moreover,the incident linear polarization wave at the specific frequency of 0.64 THz and 1.45 THz can be transformed the cross-polarization wave.Simulation results show that 90° linear polarization convertor and circular polarization generator at specific wavelength can be achieved simultaneously.(2)A infrared wavelength polarization convertor device based on the chiral metamaterials has been proposed and investigated theoretically.To avoid the metal loss in the infrared wavelength,Fabry-Perot-like cavity composed of S structure and double rods has been adopt,thus,enhancing the maximum value of transmission,reaching 0.91.At the sametime,three transmission bands can be successfully controlled by adjusting the related parameters.According the simulation result,bandwidth tunable linear polarization convertor can be achieved.(3)A polarization beam splitter device based on the anisotropic metasurface has been proposed and investigated theoretically.Owing to two dimension metamaterials,that is metasurface,easy fabrication and design,the beam splitter device based on cross-shaped structure has been designed.The investigated result show that the defection angle Y-and X-incident polarization wave and resonant frequency of 15 GHz in the simulation result are consistent with the result in the theory.Further,according to the point above,the polarization beam splitter with focusing property has been proposed.The investigated result show that the defection angle for Y-and X-incident polarization wave and focusing position at Z=40mm are consistent with the result in the theory.