Generation of high-order orbital angular momentum beams and split beams simultaneously by employing anisotropic coding metasurfaces

摘要

Metasurfaces provide the freedom to manipulate electromagnetic (EM) waves by controlling the peculiarity of subwavelength artificial structures. Many exciting devices have been developed using metasurfaces that can even perform multiple functionalities. In this paper, we propose to transform linearly polarized EM waves into high-order orbital angular momentum (OAM) beams and specifically reflected split beams for different polarizations based on anisotropic coding metasurfaces. By means of precisely adjusting the geometry of the element structure, the reflection phases of two perpendicular polarizations can be encoded without interference, which is conductive to encode the metasurfaces independently in two different directions. Under this benefit, two kinds of 2-bit phase-coded metasurfaces are constructed and verified by experiments to demonstrate their versatility of generating effective high-order OAM beams and specified reflected split beams, respectively. Beyond that, by adjusting the coding scheme, more features can be implemented under this merit.