Formation of Chiral Metamaterials by Direct Imprinting of Thin-Film Metal Elements

Terahertz metasurfaces based on 3D quasi Ω-elements were proposed and studied experimentally as well as numerically. An original method was developed for shaping new types of metallic 3D micro- and nanostructures by direct imprinting of lithographically structured 2D elements on a polymer substrate. It is shown that the embedding of microstrips into the polymer changes the magnitude of their embedding depth, making it possible to control the optical activity of the metamaterial. In this case, it is possible to achieve rotation of the plane of polarization of the transmitted linearly polarized THz radiation at an angle of more than 50° due to half-wavelength, guided-mode resonances, and diffraction effects. The results obtained pave the way to the development of large-area chiral structures for high-frequency ranges, including infrared and visible.