Study On Terahertz Phase Gradient Metasurface Lens

Today,with the rapid development of science and technology,people are increasingly pursuing the miniaturization and portability of instruments and equipment,military and civilian supplies.The adjustment of electromagnetic waves has always been adjusted through the accumulation of phases generated by media of different thicknesses.However,the birth of metasurfaces has changed this situation.The electromagnetic wave can be adjusted manually by adjusting the parameters of the material,and it can effectively solve the problems of large volume and high processing cost of traditional optical devices.As a new type of artificial material,the metasurface can control the phase,amplitude and polarization of the beam at the sub-wavelength scale,breaking the dependence on traditional optical devices.Compared with the traditional optical elements,the metasuperface structure shows novel optical phenomena,and has a more compact structure and simpler preparation process,has the ability to adjust the spatial phase,and can adjust the light wave front arbitrarily.This article describes the progress of electromagnetic wave control and phase control of metasurfaces.Starting from the basic physics for realizing complete 0-2?phase manipulation,the application overview of such metasurfaces in photonics is discussed,and the future prospects of this field are discussed.In this paper,a phase-gradient metasurface lens that achieves a good focusing effect at 1.1 THz in the terahertz band is designed.Through the design of the basic unit of the V-shaped antenna to achieve the coverage of the phase gradient of 0-2?,the directional control of the terahertz wave can be realized.And compared with the incident light of different polarizations,our metasurface lens can achieve a large numerical aperture and polarization-independent focusing effect.The experimental preparation of the terahertz metasurface lens is completed based on the micro-nano processing technology.And based on the terahertz near-field microscope for experimental measurement,we have achieved a higher resolution of up to 206 ?m by comparing terahertz with different numerical apertures.The theoretical and experimental results are consistent and can be used in integrated optics and test systems to replace traditional terahertz lenses.