Terahertz All-Dielectric Metalens: Design and Fabrication Features

— A metalens operating at terahertz band is numerically designed. By adjusting the diameters of the pillar array from 25 to 80 μm, the metalens achieves 2π-phase modulation with over 70% transmission efficiency. Further analysis indicates that tiny displacement of the focal length occurs at different wavelengths due to the chromatic aberration, and the transmission efficiency shows strong dependency on the incident angle. The influence of the power of capacitive plasma on the structure height and surface morphology properties of the single-crystal silicon is experimentally studied. An increase in the power from 15 to 75 W is found to vary the obtained structure height from 62 to 193 nm, root mean square roughness increases from 15 to 75 nm, however peak-to-peak values decreases from 12.5 to 6.1 nm, respectively.