Broadband achromatic electromagnetic beam control based on reflective metamaterial

Abstract The emergence of metasurfaces has shown great potential in planar optics. From visible light to infrared wavelengths, various forms of metasurfaces have been studied to control electromagnetic waves. Due to the dispersive properties of light waves, the application of metasurfaces in broadband devices is limited. We design a metasurface for broadband efficient achromatic transmission in the terahertz band. After optimized design, an achromatic deflector and an achromatic focusing device were obtained. By changing the geometric parameters of the metal ring to meet the phase and dispersion requirements of the metasurface, broadband achromatic metasurfaces and focusing metasurfaces are realized in the range of 1.8–2.3 THz.