Terahertz isotropic transmissive metasurfaces for generation of different wavefronts

Abstract Metasurfaces are highly advantageous in realizing the phase discontinuity of an electromagnetic wave. Aiming at manipulating electromagnetic wavefront in terahertz band, a subwavelength multilayer meta-atom is designed, and it is composed of gold mesh, gold disk, and polyimide. By varying the diameter of the central gold disk, eight meta-atoms are prepared to provide full phase modulation with phase increase of 45°. A series of transmissive metasurfaces consisting of these meta-atoms are designed with different arrays. They achieve generations of deflection, single-focusing, dual-focusing, and orbital angular momentum with and . It is noteworthy that metasurfaces assembled by these isotropic meta-atoms are polarization-insensitive. Our models are numerically verified, and all results are consistent with theoretical predictions. Different from reflective metasurfaces that sometimes encounter feeding blockage, transmissive metasurfaces are feasible for the realization of a more compact terahertz system.