Flexible chiral metamaterials in the terahertz regime: a comparative study of various designs

Five different chiral metamaterials in the terahertz (THz) regime, fabricated on fully flexible polyimide substrates, are comparatively studied via numerical calculations and experimental measurements. The chiral properties of these metamaterials, which are discussed based on their optical activity, circular dichroism, and the retrieved effective parameters, show pronounced pure optical activity (larger than 300°/wavelength), as well as important circular polarization generation and filtering capabilities. Negative refractive index is also obtained for all the considered designs.