| Due to its unique subwavelength size and artificially designed structure,metasurfaces have rapidly become the first choice for researchers in the field of electromagnetic wave regulation.In recent years,the research on metasurfaces has become more and more in-depth,and its achievements have been applied in many fields,such as vortex light generation,optical tweezers,electromagnetic stealth and abnormal refraction.Geometric phasemodulated metasurface have received much attention because their phase abrupt changes are only related to the rotation angle of the cell structure.However,they still face many problems,such as weak overall performance due to the coupling between discrete cell structures,low polarization conversion rate resulting in low overall structure efficiency,complex structure and other issues.Therefore,the suspension metasurface based on continuous geometric phase control can solve the above problems perfectly,and its single suspension structure can achieve phase mutation of 0～2.Focusing on the above problems,this paper studies and designs the catenary structure based on continuous geometric phase control.The main work is as follows :1.A beam deflector based on catenary structure is studied.The beam deflection of 30°,45° and 60° is realized by changing the parameters of catenary structure.2.An infrared perfect absorber based on catenary structure is designed.The structure consists of a top layer with four disjoint rotationally symmetrical catenary metal layers,a single layer of graphene,a silicon dielectric layer,and a substrate metal reflection layer.The device can reach 99.2 % absorptivity in the infrared band at 51.8 THZ and 84.2 THZ,achieving multi-band adjustable perfect absorption.The effects of changing the chemical potential of graphene and the thickness of each layer on the electromagnetic wave absorption of the structure were analyzed.3.The wavelength selection characteristics of the catenary structure are analyzed,and the cross-polarized light transmittance with different heights is realized under different incident wavelengths corresponding to different structural sizes.The results show that the transmittance exceeds 20 % in the 315 THZ and 357 THZ bands.On this basis,a wavelength selective Bessel beam generator based on catenary structure is designed.A single catenary structure can achieve 0-2 continuous phase coverage,which simplifies the complexity of structural design.The metasurface device is arranged in a concentric circle,the inner ring is a spiral structure,and the outer ring is a ring structure,which is used to generate Bessel beams with different topological charges. |
