Achieving wideband polarization-independent anomalous reflection for linearly polarized waves with dispersionless phase gradient metasurfaces

In this letter, we proposed to achieve wideband polarization-independent anomalous reflection for linearly polarized (LP) waves based on the phase gradient metasurface (PGM) with a dispersionless phase gradient. A polarization-keeping metasurface reflector for circularly polarized (CP) waves was firstly presented. Based on the reflector, a reflective PGM was designed to realize dispersionless but adverse phase gradients for left-and right-handed circularly polarized (LCP and RCP, respectively) waves. Under normal incidence, high-efficiency anomalous reflection occurs for both LCP and RCP waves with opposite-signed reflection angles. Under the LP wave incidence, the reflected waves are separated into two beams due to the decomposition of LP waves into LCP and RCP waves. The anomalous reflection of LP waves is independent of the polarization angle. Both the experimental and simulated results are consistent with theoretical predictions, which convincingly verifies the wideband polarization-independent anomalous reflection of LP waves.