Conjugated bi-layer C8 metamaterials are proposed. Chirality and refractive index can be controlled effectively by the structure geometry. Extreme chirality results in a high negative refractive index for both right- and left-circular polarized excitations. The conjugated bi-layer C8 structures are fabricated and tested in microwave regimes. The measurement results are in good agreement with the simulation results. These proposed structures are additional promising candidates for high negative refractive index metamaterials which will facilitate different applications.
Chirality can be manipulated in multilayer three-dimensional helices. Multiple backbone helices can be effectively designed and fabricated, preserving their unique electromagnetic properties of chiral metamaterials. Chirality is boosted in double helices. The chirality index is four times higher than in single helices. Based on the extreme chirality, the effective refractive index of the 3D double helices is proved to be negative, with low loss.
Thin and flexible bi-layer terahertz chiral metamaterials are experimentally demonstrated in both handednesses at terahertz frequencies. The structures are made of conjugated C8 metallic resonators fabricated on a flexible polyimide substrate. These structures exhibit chirality and can distinguish circularly polarized waves at the frequency range from 0.5 to 0.9 THz, equivalent to 57.15% bandwidth. The structures can be used as circular polarizers for terahertz waves.
Metamaterials with near-zero refractive index designed using fishnet structures are proposed. The near-zero-index band is generated with the overlap of electric and magnetic resonances, where the transition from a negative-n region to a positive-n region is found. Both the permittivity and the permeability are controlled via geometrical parameters and the structure orientation, and are near-zero within the operating band, resulting in low loss transmission. As the number of layers increases, the transmission band becomes broader and moves to lower frequency. The experimental results confirm that such designs can generate a near-zero refractive index with low loss within an operating frequency band.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.