Independent wavefront manipulation based on multifunctional terahertz metasurface

In this paper, a full-space metasurface is designed to control the transmitted circularly polarized waves and reflected linearly polarized waves independently at two different terahertz frequencies. The proposed metasurface unit consists of two layers of metal patches with complex patterns and a dielectric layer connected in the middle with an extremely low profile. It can convert a left-handed circularly polarized incident wave into a right-handed circularly polarized transmitted wave at a frequency of 1.27 THz and convert an incident x-polarization wave into a y-polarization reflected wave at 3.07 THz, both with high conversion efficiencies. By changing the geometric parameters of two resonators, the emergent phase of the two frequencies can be controlled arbitrarily in the range of 360°. In order to verify the versatility advantage of this metasurface in electromagnetic wavefront modulation, a dual-band orbital angular momentum generator and holographic imaging are designed and verified. This design concept provides a new idea for realizing multi-band and multi-polarization controlled metasurface, and the method can be extended to other bands such as millimeter wave.