Generating reflective vortex waves in microwave region by metasurface
In this paper, anomalous reflection for circularly polarized (CP) waves is proposed to achieve, where the reflected waves possess orbital angular momentum (OAM) along their direction of propagation based on the Pancharatnam-Berry (geometrical) phase. Based on the phase gradient metasurface (PGM), we firstly presented a polarization-converting metasurface reflector for circularly polarized waves. On the basis of the reflector, two reflective vortex plates were designed. Under normal incidence, high-efficiency vortex waves are obtained by illuminating one vortex plate. Under oblique incidence, high-efficiency anomalous reflection of votex waves occurs for circularly polarized waves with 0° reflection angle by illuminating the other votex plate. The results of experiment and simulation are both accordant with theoretical prediction, which convincingly verifies the high-efficiency anomalous reflection of votex waves of CP waves. This technology makes a remarkable progress which is beneficial to put metasurface into practical application.