Multifunctional reflective dielectric metasurface in the terahertz region.

The recent emergence of digital coding metasurfaces has significantly simplified the design of functional devices and manipulated electromagnetic waves digitally. In this paper, we propose a dielectric coding metasurface with different functions, which is implemented by a metasurface with specific coding sequences. It is composed of a three-dimensional T-shaped dielectric block placed on a metal plate. Compared with traditional metal resonators, the all-dielectric metasurface has relatively low loss and the reflection amplitude maintains a high value. Here, we demonstrate five different functions of anomalous reflection, beam splitting, diffuse scattering, line focusing, and vortex beam generation achieved under normal incidence of the linearly polarized wave. Through full-wave numerical simulation, the far-field scattering patterns and near-field electric-field intensity distribution of the proposed metasurface under various reflection conditions are obtained, which is in good agreement with the theoretical prediction. It is verified that the multifunctional dielectric coding metasurface provides a new way to control the reflection of terahertz waves.