Manipulation of main lobe number and azimuth angle of terahertz-transmitted beams by matrix-form-coding metasurface

To flexibly control the main lobes number and azimuth angle of terahertz-transmitted beams, we here propose a kind of matrix-form-coding metasurface. Coding metasurfaces are artificial structures composed of periodic or nonperiodic subwavelength unit cells, which are a kind of equivalent material that is made by replacing elementary particles such as molecules and atoms of natural materials with ordered artificial "particles". By critically design of coding modes, the azimuth and elevation of the transmitted terahertz beam can be flexibly manipulated. Particularly, the 1-bit coding is realized in x-direction coding, y-direction coding, and the chessboard coding. The combination of 2-bit and 1-bit coding forms a chessboard coding in the form of matrix, so as to flexibly control the azimuth and elevation of the transmitted beam and control the number of main lobes. Our coding method can flexibly control the azimuth of the beam and effectively reduce the energy of the side lobes. This work opens up a new digital perspective for new methods of metamaterials, making it possible to combine electromagnetic wave manipulation with digital signal processing.