A bilayered chiral metamaterial is proposed and demonstrated to exhibit dual-band asymmetric transmission of linearly polarized electromagnetic waves in two opposite directions. Simulated and measured results show that the bilayered chiral metamaterial can achieve cross-polarization conversion with an efficiency of over 90% for both y- and x-polarized waves. The proposed metasurface can be regarded as an ultrathin polarization-controlled switch that is easily switched on/off by changing a linearly polarized wave to its orthogonal component.

Polarization manipulations of electromagnetic waves can be obtained by chiral and anisotropic metamaterials routinely, but the dynamic and high-efficiency modulations of chiral properties still remain challenging at the terahertz range. Here, we theoretically demonstrate a new scheme for realizing thermal-controlled chirality using a hybrid terahertz metamaterial with embedded vanadium dioxide (VO₂) films. The phase transition of VO₂ films in 90° twisted E-shaped resonators enables high-efficiency thermal modulation of linear polarization conversion. The asymmetric transmission of linearly polarized wave and circular dichroism simultaneously exhibit a pronounced switching effect dictated by temperature-controlled conductivity of VO₂ inclusions. The proposed hybrid metamaterial design opens exciting possibilities to achieve dynamic modulation of terahertz waves and further develop tunable terahertz polarization devices.

We present an ultrathin dual-band plasmonic waveguide and frequency splitter experimentally based on designer surface plasmon polaritons (DSPPs) of planar composite periodic gratings. In such planar plasmonic metamaterials, the electromagnetic wave can be tightly confined around an ultrathin metallic grating, and the propagation of DSPPs strongly depends on the dispersion relation determined by the depth of groove. Based on such features, we design and fabricate an ultrathin composite grating to support two DSPP modes, which exhibit low bending loss in the bending surface plasmon polariton (SPP) waveguide. We further propose an ultrathin SPP frequency splitter by adjusting the groove depths of two branches. The experimental results are in good agreement to the numerical simulations.

Terahertz radiation refers to a broad electromagnetic spectrum range between microwave and infrared waves, which is also known as the terahertz gap due to inadequate materials and technologies for its generation and manipulation.

A helicity-dependent computational ghost image generated by a metasurface hologram offers a promising optical encryption scheme.

A broadband asymmetric transmission of linearly polarized waves with totally suppressed copolarization transmission is experimentally demonstrated in ultrathin 90°-twisted Babinet-inverted metasurfaces constructed by an array of asymmetrically split ring apertures. The only accessible direction-dependent cross-polarization transmission is allowed in this anisotropic chiral metamaterial. Through full-wave simulation and experiment results, the bilayered Babinet-inverted metasurface reveals broadband artificial chirality and asymmetric transmission, with a transmission contrast that is better than 17.7 dB within a 50% relative bandwidth for two opposite directions. In particular, we can modify polarization conversion efficiency and the bandwidth of asymmetric transmission via parametric study.