Design and computation on high transmission metasurface for subwavelength focusing of terahertz waves

In this paper, a high transmission metasurface for subwavelength focusing of terahertz waves was proposed. A full 2π phase coverage with high transmission at target frequency was designed by varying the lengths of the cross resonators. The high transmission characteristics of the resonators were analyzed and the performance of the focusing was also discussed. The results show that the maximum transmission of the resonators reaches 0.92 and the terahertz wave can be focused with at the focusing point of a full width at half-maximum of 143 μm, which agrees well with the full width at half-maximum of 139 μm obtained by Huygens' principle. This device with the characteristics of flexible, thin and easy-integration exhibits the potential applications in THz imaging and communications, and also can be extended in the design of other planar THz components easily.