Broadband and Wide-Incident-Angle Anomalous Reflection Multifunctional Metagrating

Anomalous reflection efficiency is limited in the case of large deflection angles. In this letter, we design a metagrating that can maintain high efficiency in an incident angle range of 10 degrees-60 degrees with a fractional bandwidth up to 55.3%. By adjusting the period of the metagrating, only the 0th and -1st-diffraction orders exist under oblique incidence. The unit cell of the metagrating consists of two metal rings, which exhibit a pi phase difference and can shut down the 0th-order diffraction mode. Therefore, only the -1st-order anomalous reflection can be achieved under oblique incidence conditions. Simulated and experimental results demonstrate that the proposed metagrating can achieve anomalous reflection at broadband and large angles. Furthermore, a multifunctional metagrating can be implemented by redesigning the metal rings, which have various functions of anomalous reflection, polarization selection, and multibeam generation.