Design of High-Transmittance All-Dielectric Focusing Metasurface With Polarization-Controllable Focus

A high-transmittance all-dielectric focusing metasurface (MS) with polarization-controllable focus is proposed and experimentally applied in the $Ku$ -band. The MS is based on a single-layer dielectric structure consisting of cross-shaped dielectric elements. Without the use of any metallic unit, the dielectric element shows a high transmission magnitude of up to 0.95 and a nearly full phase-control coverage of about 330°. Moreover, the element is polarization-sensitive, capable of providing different phase gradients for the orthogonally polarized incident waves. As a result, two spatially separated foci can be obtained for the orthogonal polarizations through the focusing MS, and the focal positions can be independently controlled by tuning the lengths of the two orthogonal arms of the cross-shaped dielectric elements. For verification, a prototype of the dielectric focusing MS is fabricated and measured. A separation of more than two wavelengths between the two polarization-dependent foci is obtained. The high levels of polarization sensitivity, design freedom, and transmittance (89%) make the proposed all-dielectric MS a promising material for use in polarization detection, wireless communication, and power transfer systems.