Research On Multifunctional Phase Metasurface And Its OAM Beam Generation

As a new type of electromagnetic device based on sub-wavelength structural units,phased metasurfaces have received a lot of attention from researchers in recent years due to their powerful ability to manipulate electromagnetic waves.Orbital Angular Momentum(OAM)is important for improving spectrum efficiency and the development of wireless communication technology by adding a new dimension to the traditional domain of electromagnetic waves,such as intensity and phase.The OAM beam generation technology based on phase metasurfaces greatly simplifies the traditional OAM beam generation method,with the advantages of simple structure,low cost and easy processing.This paper studies the multifunctional phase metasurfaces and orbital angular momentum waves.Through the analysis of the basic principles of phase metasurfaces and phase modulation methods,two multi-functional phase metasurfaces are proposed.Combined with the basic theory of orbital angular momentum waves,an orbital angular momentum beam generator based on multi-functional phase super-surfaces is designed.The main works of this paper are:(1)A new dual-band linear polarization phase super-surface unit is designed,which realizes dual-band linear polarization beam deflection,focusing lens and four-beam modulation.(2)The corresponding OAM beam generator is designed based on the dual-band metasurface and orbital angular momentum theory,and the modulation of the arbitrary deflection angle of the OAM beam is achieved by analyzing the phase superposition theory.The simulation and experimental results are in good agreement.(3)The basic principles and modulation of the transmitted and geometric phases in the phase metasurface are analyzed,and a left circular polarization and right circular polarization multiplexing method is proposed.A polarization multiplexing metasurface unit is designed to realize independent modulation of the left circular polarization and right circular polarization beams.(4)Based on the designed polarization multiplexing metasurface unit and orbital angular momentum theory,an OAM beam generator with independent modulation of left circular polarization waves and right circular polarization waves is designed.