Topological Transformation OAM Based on Metasurface Generated Bessel Beam

Metasurfaces have provided new opportunities to control electromagnetic waves, which may find applications in areas such as wireless communications, imaging, energy harvesting, and invisible cloaks. Among all of the applications, Bessel beams and orbital angular momentum (OAM) beams have been investigated extensively. The combination of Bessel beam and OAM can engender some interesting phenomenon. In this work, we report a topological transformation of mode in the transmission of OAM using millimeter wave metasurface. Unit cell of the metasurface is designed to adjust phase of the transmitted wave. Two kinds of Bessel beams carrying OAM are encoded simultaneously with a crossed arrangement. Simulation results show that with the propagation of the beam, the mode number of OAM transformed from one to four and the energy delivered to all four modes. This work may be helpful in the transportation exploring of OAM and can be used in multifunction wireless communication.