Proposing a reconfigurable bi-lateral graphene-based meta-surface for wide-band independent OAM generation in transmit/ reflect modes

Orbital angular momentum (OAM) vortex waves attract a lot of attention due to their application in various areas, and specifically in next-generation communication. On the other hand, the development of graphene-based active metasurfaces is increasing due to its significant benefits. In this paper, a tunable graphene-based metasurface is proposed for generating an OAM beam with various topological charges in the terahertz (THz) frequency range. The goal of this work is the operation of a metasurface in three operating modes: transmission, reflection, and transmission/reflection simultaneously. The incident beam can be reflected, transmitted, or divided equally into transmitted/ reflected beams with independent OAM modes. Generation of OAM topological charge or switching in three operating modes can be achieved by changing the chemical potential of graphene. The proposed metasurface can produce an OAM beam in both half-spaces separately and continuously. Suppose a horn antenna is placed as the feed of the metasurface. In that case, a bi-lateral antenna can be achieved, which is useful for multichannel communication, free space communication, next-gen communication, minimization systems, etc.