Flexible terahertz optics: light beam profile engineering via C-shaped metallic metasurface

Abstract

The potential of terahertz (THz) imaging implementation in a large variety of applications requires compact, reliable, and relatively low-cost solutions in systems constituents. Here we focus on the development of passive optical elements and demonstrate flexible and reliable THz beam profile engineering for imaging aims via mechanical bending of a stainless steel-based C-shaped metasurface. The designed and laser-ablation technology fabricated metasurface provides compact THz focusing and enables THz light engineering as well as polarization control ability in THz imaging. Focusing, light profile engineering, and polarization control performances of the metasurfaces with different focal distances and C-shape designs are presented. Experimental data are well supported by simulations, using Finite Difference Time Domain (FDTD) method. THz images of different objects at ∼94 GHz using InP Gunn diode, bow-tie sensors, and exclusively metasurfaces-based optics are exposed. Further routes in the development of low-cost multicolor and polarization-sensitive THz imaging are discussed.

Study of the low-cost HIPS and paraffin-based terahertz optical components

“…It is seen that the experimental intensity maximums are shifted to longer distances, compared to the simulated ones, which are most noticeable for the lenses of 20 mm focal length. That might be caused by fabrication imperfections and nonparaxial effects occurring in small focal length optical devices [9]. One may note the increase of the intensity with the increase of focal distance for the case of simulated lenses.…”

“…Currently, typically employed optics are usually made of silicon [6], Tef-lon [7] or special z-cut quartz [8]; however, they require a special manufacturing equipment. Another solution for THz beam shaping is the employment of complementary meta-lenses [9], allowing conduction of exciting experiments and being comparably simple to fabricate. Still, specific machinery, which may not be easily accessible, is required.…”