Broadband Chiral Metasurface for Spin-Selective Anomalous Reflection and Absorption

Chiral metasurface has attracted great amounts of interest for spin-selective wave-front manipulation of electromagnetic waves yet it still faces challenges. Here, a novel circular dichroism unit cell is reported. Lumped resistors are integrated into the I-shaped split ring to break n-fold (n>2) rotational symmetries, which introduces broadband spin- independent absorption and provides an auxiliary degree of freedom for developing spin-selective meta-devices. As validation, a gradient metasurface is theoretically simulated. From 10 to 16 GHz, the incident left-handed circularly polarized waves are converted into their orthogonal polarization and anomalously reflected. In contrast, the incident right-handed circularly polarized waves are almost completely absorbed. Our work may find applications in multi-functional systems.