High-efficiency metagrating for broadband with a large deflection angle at terahertz frequency

Terahertz metasurface lenses are widely used due to their high design flexibility and ultra-thin characteristics, but they have an inherent bottleneck of a significant decrease in efficiency when turning large-angle beams. Therefore, this paper proposes a metagrating, aiming to develop terahertz devices with wideband response, large-angle control, and efficient beam deflection. The results demonstrate that when the deflection angle is 71.3°, the efficiency exceeds 70%. In addition, within a relative bandwidth of 15%, the metagrating maintains a diffraction efficiency exceeding 50%, and the beam deflection range is 56.79° to 84.88°. This research has confirmed the outstanding potential of metagrating to achieve high efficiency, broadband, and large-angle beam deflection.