Based On The Chiral Metasurface Circular Polarized Electromagnetic Wave Selective Reflector

Metasurfaces are two-dimensional versions of metamaterials.Because they are easy to manufacture and have powerful capabilities in electromagnetic wave control,they have attracted widespread attention.However,so far,most of these proven metasurfaces are based on achiral meta-atoms,and perform the same efficiency on the amplitude and phase modulation of left-hand circular polarization(LHCP)and right-hand circular polarization(RHCP)waves,the spin-selective metasurface that exhibits different reflection characteristics of circularly polarized waves is less discussed.In response to this problem,this paper combines the characteristics of the chiral structure with the Pancharatnam-Berry(PB)phase theory,and proposes a design method of dual-function reflector,which realizes the selective reflection of circularly polarized electromagnetic waves and the generation of vortex electromagnetic waves.The reflection device designed in this article will have broad application prospects in the fields of spin-selective modulation of wavefront,circularly polarized wave detection,polarization conversion,and wireless communication.The main research contents are as follows:First,the working mechanism of spin selective reflection of circularly polarized electromagnetic waves and the characteristics of vortex electromagnetic waves are studied.Through the introduction of various polarization forms of electromagnetic waves,the derivation of spin selection theory,and the analysis of the angular momentum of vortex electromagnetic waves,it provides a theoretical basis for the design of circularly polarized electromagnetic wave selective reflection devices.Next,the design of a chiral metasurface tailored for spin-selective abnormal reflection and the generation of vortex waves carrying orbital angular momentum(OAM)was completed.First,according to the basic characteristics of the chiral structure,a chiral unit suitable for spin selective reflection is proposed,that is,asymmetric ?-type and ?-type resonators are embedded in each other as the basic element of strong circular dichroism.By introducing chiral resonance to achieve spin-dependent reflection and absorption.According to the PB phase theory,the phase is changed by adjusting the geometric azimuth angle of the metal pattern on the surface of the element atom,so as to realize the phase condition required by the vortex electromagnetic wave,and lay the foundation for the realization of the subsequent circularly polarized electromagnetic wave selective reflection device.Then,through using MATLAB and HFSS co-simulation method to quickly build a chiral metasurface model,and complete the simulation in the HFSS software.Then the near-field electric field amplitude distribution,phase distribution and far-field pattern distribution of the chiral metasurface is analyzed and the performance of selective reflection of circularly polarized waves and the generation of vortex electromagnetic waves is verified.Finally,the PCB printed circuit board technology is used to prepare the physical object and carry out the experimental test.By comparing the measured near-field electric field amplitude distribution,phase distribution and far-field pattern data with the simulation results,the function of the reflector for the circular polarization spin selective reflection and vortex electromagnetic wave generation is verified,and then complete all the work of this subject.