Real-Time Mode-Agile and Multiplexing of Bidirectional OAM Waves Based on Intelligence Transmit-Reflect-Integration Metasurface

Electromagnetic (EM) waves carrying orbital angular momentum (OAM) have great potential for application in wireless communication systems due to mode orthogonality. However, the current studies are mostly subject to static EM manipulation and limited half-spatial coverage. To expand the flexibility of OAM waves and spatial coverage, a wideband intelligent transmit-reflect-integration metasurface (TRI-MS) is proposed to achieve real-time mode-agile, multimode multiplexing, and bidirectional OAM waves. At the unit level, two positive intrinsic negative (p-i-n) diodes are integrated into the magnetoelectric-type unit cell to achieve real-time manipulation of the amplitude and phase of full-space EM waves. At the array level, we developed a single-mode purity optimization method for full-space OAM-mode agility and introduced an aperture partitioning method based on the particle swarm optimization (PSO) algorithm for multimode multiplexing. As verification, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$16\times 16$ </tex-math></inline-formula> element array is developed and fabricated. The simulated and measured results of the prototype demonstrate the capability of real-time OAM-mode switching and multiplexing within bidirectional OAM wave coverage, thus generating OAM waves with the mode of −3 to +3. The results show that the proposed design has potential applications in channel capacity enhancement and bidirectional data transmission.