چكيده به لاتين
In recent years, there has been notable advancement in programmable metasurfaces, primarily attributed to their cost-effectiveness and capacity to manipulate electromagnetic (EM) waves. Nevertheless, a significant limitation of numerous available metasurfaces is their capability to influence wavefronts only in reflection mode or transmission mode, thus catering to only half of the spatial coverage. To the best of our knowledge and for the first time, a novel graphene-assisted reprogrammable metasurface that offers the unprecedented capability to independently and concurrently manipulate EM waves within both half-spaces has been introduced in the THz frequency band. This intelligent programmable metasurface achieves wavefront control in reflection, transmission, and the concurrent reflection-transmission mode, all within the same polarization and frequency channel. The meta-atom is constructed with three graphene sections, enabling straightforward modification of wave behavior by adjusting the chemical potential distribution within each graphene segment via an external electronic source. Beyond real-time control of reflection and transmission modes, this approach also empowers the manipulation of wavefronts by governing the phases of these modes. The proposed functionalities encompass various programmable modes, including single and dual beam control in reflection mode, dual beam control in transmission mode, simultaneous control of direct transmission alongside two beams in reflection mode, and vice versa, and controlling a single beam in reflection mode and two beams in transmission mode simultaneously. Furthermore, we extended our exploration beyond wavefront manipulation in individual or continuous reflection and transmission modes. In fact, the structure possesses the capability to transform the proposed metasurface into an absorber and polarizer, as well. By changing the chemical potential of each graphene segment, it can selectively absorb incident waves at different frequencies. Also, by manipulating the incident wave polarization, it can convert linear polarization to circular polarization in both reflection and transmission modes. The proposed metasurface is expected to be reprogrammable due to wavefront manipulation in both half-spaces separately and continuously as well as polarization and absorption frequency control for various applications such as imaging systems, encryption, remote sensing, miniaturized systems, and next-generation wireless intelligent communications.
