Generation of Orbital Angular Momentum Vortex Waves on Both Sides of the Cascaded Metasurfaces

In this paper, the cascaded metasurface is proposed for simultaneous control of the reflected and transmitted wavefronts to generate vortex beams carrying orbital angular momentum (OAM). The metasurface is composed of four metallic layers and the amplitude and phase of reflection and transmission can be controlled independently. The simulation results show that the x-polarized incident waves can be reflected into the OAM vortex beam with l=3, while the y-polarized incident waves can be transmitted into the OAM vortex beam with l=2.