Ultra-Wideband Low-Loss Control of Terahertz Scatterings via an All-Dielectric Coding Metasurface

Despite the growing interests for controlling terahertz (THz) scatterings via metallic metasurfaces, the avoidance of Ohmic loss resulting from the interaction between light and phonons or free electrons remains an arduous task. Herein, we propose a new approach of ultra-wideband low-loss control of THz scatterings via an all-dielectric coding metasurface (DCMF). In our experiments, the DCMFs manipulate THz waves remarkably in an ultra-wideband of 900 GHz. When a THz wave enters into the DCMFs, it emerges split into two beams with a higher amplitude of transmission up to 60% and the lower amplitude about 30%. In our simulations, the high amplitude of transmission may even reach 99%. Besides, the variation of coding sequence enables diversification of manipulation for THz scatterings. Notably, the DCMF with the sequence of "101010..." refracts a beam of 1.3 THz in two directions. The energy of the main beam seems to dissipate in all directions. We also find that as a beam of 1.63 THz passes through the DCMFs consisting of the sequence of "110110...", its energy may scatter in multiple directions, demonstrating an unprecedented control of THz scatterings. Our results not only enrich the strategy of THz modulation but also guide the superior design for THz devices.