Asymmetric all Silicon Micro-Antenna Array for High Angle Beam Bending in Terahertz Band

Phase mapping of metasurfaces with a finite number of elements is popular in wavefront manipulation. However, in high angle beam bending, the efficiency of bending beams drastically drops, which will greatly limit the applications of metasurface in photonic devices. Here, we propose an all silicon asymmetric dimer micro-antenna array used as meta-grating to achieve large bending angle and high efficiency for both P- and S- polarized incident wave at 0.3 THz. The geometric structure of the dimer consisting of one solid and one hollow pillar was meticulously optimized to realize a large bending angle of 70.2° with the diffraction efficiency of 73.1% and 37.8% for the P- and S- polarizations, respectively. The proposed all silicon metasurface can be easily prepared with CMOS technology, and can be used in flat lenses with high numerical aperture or other photonic devices in THz range.