Reconfigurable chiral metasurface for tailoring circular dichroism to realize switchable circularly polarized OAM multi-modal/selective generation and absorption

Metasurfaces or artificial electromagnetic structures offer viable solutions for electromagnetic (EM) wave manipulation with their compact periodic configurations. Tunable metasurfaces capable of controlling wavefronts are highly desirable in numerous engineering and scientific applications. This paper presents the design and implementation of a reconfigurable electromagnetic metasurface based on circular dichroism (CD), which integrates PIN diodes to achieve dynamic manipulation of circularly polarized (CP) waves and enables vortex beam generation under corresponding states. The metasurface consists of a 30 × 30 array of meta-atoms, each independently controllable. By switching the diode states, each meta-atom switch between functioning as a high-efficiency reflector, high-efficiency absorber, left-handed circular polarization (LHCP) metamirror, and right-handed circular polarization (RHCP) metamirror. Leveraging the Pancharatnam-Berry (PB) phase principle, chiral mirror elements are arranged in arrays to generate vortex beams. Through simulations and experimental verification, the metasurface achieves multi-modal generation by simultaneously generating vortex beams with topological charges l = + 1 and l = −1, enables selective generation of orbital angular momentum (OAM) modes to produce vortex beams carrying either l = + 1 or l = −1 topological charge, and demonstrates efficient absorption of CP beams under specific operational conditions. The device demonstrates superior performance in the 8.5–13.5 GHz frequency range, providing innovative technical approaches for optics, communications, quantum technologies, biomedicine, and other fields. It is expected to enhance information transmission efficiency, strengthen optical manipulation capabilities, and drive the realization of more cutting-edge applications.