Multi-Frequency Holographic Imaging High-Transmission Complex-Amplitude Metasurface

Electromagnetic waves are closely related to our lives.To realize the application of electromagnetic waves,we must adjust them arbitrarily.As a new type of artificial electromagnetic material,metasurfaces are usually composed of two-dimensional arrays or other spatial arrangements of unit structures,and have the unique ability to arbitrarily modulate the phase,amplitude and polarization of electromagnetic waves.The study of the multiplexed metasurface can provide the possibility for the further integrated development of the information encryption and decryption system integrated with the transceiver.In this paper,a multi-frequency superstructure surface is designed,which can independently provide common modulation of amplitude and phase at multiple required frequencies.Based on the proposed dual-frequency metaatom,the applications of metasurface lens imaging and holographic imaging are designed.Firstly,two kinds of meta-atoms,C-shaped and cos curve-shaped,working in a single microwave frequency band are introduced.The structure design of the two meta-atoms and the simulation of related characteristics are carried out.Both of these meta-atoms can achieve cross-polarization in a single microwave frequency band.The continuous coverage of the transmitted wave amplitude 0?0.5 and phase-???,and changing the corresponding parameters can achieve independent adjustment of amplitude and phase.In order to realize a dual-frequency unit,the final optimized structure is a combination of a larger C-shaped slot structure and a smaller cos-shaped strip structure,so that the meta-atom can work in two operating frequency bands of10 GHz and 13 GHz,and in two different polarization selection capabilities are realized on the frequency band.In order to verify the performance of the C-cos slot-complementary dualfrequency meta-atom,a metasurface lens was designed using the quasi-optical path theorem,and the single focus focusing function was realized in both the 10 GHz and13GHz frequency bands.Then,a simple metal plate with etched horizontal and vertical slits is added at the incident position,and the electric field distribution of the cross-polarized transmitted wave shows the imaging ability of the lens.Finally,a metal plate etched with complex images was used to further verify the imaging capability of the metasurface lens.In addition,by designing the polarization information,the meta-lens can image the incident information of y polarization at 10 GHz and the incident information of x polarization at 13 GHz,demonstrating its ability to select polarization.The test results show that the imaging results of the superstructured surface lens are good.Next,the application of holographic imaging is also realized based on the C-cos slot-complementary dual-frequency superstructure surface meta-atom.Designed and implemented a metasurface for multi-focus imaging,and compared the complex amplitude holographic imaging results based on the point source method with the pure phase holographic imaging results based on the GSW algorithm.It was verified that the two algorithms can achieve metasurface holographic imaging.The complex images "H" and "V" were preset at 10 GHz and 13 GHz,respectively,and a metasurface capable of holographic imaging was designed.Finally,the physical processing and testing of the holographic metasurface are carried out,and the test results are compared with the simulation results to verify the performance and imaging capabilities of the metasurface.