Reflectionless metasurface with high refractive index in the terahertz waveband

Abstract

Terahertz flat optics is a design concept for replacing conventional three-dimensional bulky optical components with two-dimensional ultra-thin optical components. However, high refractive index materials suitable for flat optics are frequently subject to high Fresnel reflections due to the cumbersome control of the relative permeability it requires. Here we experimentally demonstrate a reflectionless metasurface with a high refractive index of 5.88 + j1.57, extremely low reflectance of 1.3%, high relative permittivity of 6.73 + j0.85, and the high relative permeability of 5.03 + j2.11 at 2.97 THz. The super-fine ink-jet printer using silver paste ink fabricates the metasurface consisting of 80,036 pairs of cut metal wires on both the front and back of a 5 μm-thick polyimide film. The findings also demonstrate that weak conductors as well as good conductors can be used in the design of reflectionless metasurfaces with a high refractive index in the terahertz waveband. The presented metasurface can offer an accessible platform for terahertz flat optics in 6G (beyond 5G) wireless communications and imaging.

Optimization of plotter printing for sub-terahertz metallic metasurfaces fabrication on ultra-thin substrate

“…This standard technology allows resolutions of the order of 50 µm to be achieved with an average deposited thickness of 150-200 nm in a single pass. To increase the resolution, electrodynamic or electrohydrodynamic jet printing [38][39][40][41] or aerosol jet printing [42][43][44] have been developed. They allow the resolution to reach the micrometer range, but this is at the expense of the deposited thickness.…”