基于几何相位的高透射型太赫兹超表面设计OACSTPCD

A transmission-type metasurface based on geometric phase is proposed.By designing and arranging the unit structures of the metasurface,the wavefront of the incident circularly polarized waves is manipulated arbitrarily and the terahertz vortex waves are generated.The metasurface unit consists of a typical ″sandwich″ structure,that is,a metal-dielectric-metal structure,the top and bottom metal patterns of which are composed of C-shaped and rectangular elements.By utilizing the principles of geometric phase,the phase of the transmitted light can be controlled by rotating the metal structure at the operating frequency,while maintaining a high cross-polarization transmission amplitude(>0.9).By rotating code of the unit structures,an encoded metasurface is formed capable of generating anomalous deflection phenomena and vortex beams with different topological charges.Simulation results demonstrate that at 0.63 THz,the designed encoded metasurface exhibits effective control over electromagnetic waves,producing anomalous refraction with deflection angles of±50.1° and 30°,as well as vortex beams with topological charges of l=±1.This research holds potential applications in areas such as laser radar and terahertz high-capacity communication.