Dual-Phase Hybrid Metasurface for Independent Amplitude and Phase Control of Circularly Polarized Wave

Achieving independent control of the amplitude and phase of the electromagnetic (EM) wave by a thin flat device is very important in wireless and photonic communications. However, most of the reported metasurfaces, so far, have realized only the simultaneous control of the amplitude and phase of the linearly polarized EM wave. This communication presents a strategy to realize the independent and arbitrary control of the amplitude and phase responses for the circularly polarized EM wave by using a dual-phase hybrid metasurface that integrates both geometric and propagation phases. A beam deflector with a tailorable amplitude is then designed to verify the proposed strategy. As a proof of concept of its practical application, a circularly polarized reflector antenna with a high gain and an extremely low sidelobe is implemented by the proposed metasurface. Experimental results are in good accordance with the simulation ones, demonstrating that the sidelobe of the designed antenna can be reduced by 8 dB compared with a reflector antenna actualized by the phase-only metasurface. The proposed methodology and the metasurface can provide a new degree of freedom in controlling the circularly polarized waves by simultaneous phase and amplitude modulations, which may trigger many interests in EM/optical integration and complex EM-wave manipulations, as well as advanced metadevices for real-world applications.