Research On Metasurface Devices Based On Trapezoidal Cell Structure

Metasurface is the two-dimensional counterpart of metamaterials.Metasurface is a two-dimensional array structure composed of unit structures arranged according to a certain rule,and the unit structures ’size is smaller than the incident wavelength.Metasurface can flexibly control the polarization,amplitude,and phase parameters of electromagnetic waves by designing the shape,size,and azimuth angle of the unit structures.Therefore,metasurface has great potential in applications such as planar lenses,holography,beam shaping,and polarizing devices.The main research of this thesis can be divided into two parts,as follows:1.Based on the transmission phase theory,optimize the structural parameters of the trapezoidal element,and design the metasurface deflector and lens.Using the proposed trapezoidal structure antenna,the phase is regulated by changing the geometrical parameters of the element structure based on the transmission phase theory.Under the incidence of linearly polarized light with a wavelength of 640 nm,the deflection of the beam is realized,and a lens based on a trapezoidal structure is designed.In addition,by changing the lattice period of the unit structure,the effect of different lattice periods on the focusing performance of the lens is studied,and the highest focusing efficiency can reach 47%.2.Based on the geometric phase theory,selected rotation angle of the unit structure and designed the metasurface deflector and lens.Using the proposed trapezoidal structure antenna,based on the geometric phase theory,optimizing the parameters of the unit structure,and rotate the unit structures when cell structure transmittance is highest,the phase control can be realized under the incident left-handed circularly polarized light with a wavelength of 640 nm.Beam deflectors and lenses are designed.The beam deflectors designed with different numbers and different lattice periods of structural units are studied,and the theoretical calculation values are basically consistent with the simulation values.Types of polarized light,and focusing of lenses with different focal lengths are also studied.