Vortex Light Study Based On Phase Control Of Metasurface

Since the birth of metasurfaces,researchers have used the dichroism of metasurfaces to realize the phase control of transmitted light/reflected light.Metasurfaces have shown important application potential in integrated optics,optical communications,etc.The constituent units of metasurfaces can control the propagation direction,phase,and amplitude of light through electromagnetic responses.By arranging a series of unit structures with gradually changing structure sizes in a specific order,a discontinuous distribution in phase can be achieved,thereby realizing modulation of incident light.Metasurfaces have powerful optical properties and electromagnetic control capabilities,providing more possibilities for holographic optics,optical imaging,and electromagnetic stealth.In this paper,a U-shaped unit structure is first designed.By appropriately changing the geometric parameters of the U-shaped unit structure,the cross-polarized light can achieve a phase shift of 0-2π.The U-shaped unit structure selected in this paper has unique symmetry,and through a series of formula derivation,it is found that the optical device composed of the U-shaped unit structure with unique symmetry also has polarization-independent properties.A beam deflector that can realize anomalous refraction is designed by using the U-shaped unit structure.When light with different polarization states is incident on the beam deflector,the beam deflection phenomenon of the orthogonally polarized transmission field obtained is the same and can be solved theoretically.Based on the beam deflector,the effect of lattice constant and different incident angles on the deflection phenomenon was further explored.Based on the U-shaped unit structure,a metalens to achieve focusing was designed.Similarly,with four different polarization states of light incident,the beam focusing results obtained by the simulation are the same.Focusing effect based on metalens Finally,the focusing ability of metalens with different incident angles and the focusing effects of metalens with different focal lengths are simulated and analyzed.Through the analysis of the simulation results,it is found that the optical devices designed in this paper have polarization-independent characteristics.