Polarization-frequency multiplexed terahertz reconfigurable metasurface for diversified vortex beams generation and multi-spot patterns in full-space enabled by vanadium dioxide

Abstract This paper presents a terahertz (THz) metasurface with polarization-frequency multiplexing capability that uses vanadium dioxide (VO 2 ) to achieve dynamic wavefront control. The design leverages the phase transition of VO 2 to switch between reflective and transmissive operational modes. In the metallic state, the metasurface operates reflectively to form four channels under linear polarizations ( x -LP and y -LP) at 0.8 THz and 1.3 THz, generating diverse orbital angular momentum beams such as dual-, quadruple-, and octuple-vortex arrays. In the insulating state, it functions transmissively, creating two channels under x -LP and y -LP incidences at 0.8 THz via independent phase modulation, which produces multi-spot focal patterns like cross/X-shaped distributions and an eight-spot array. This work demonstrates full-space, six-channel (four reflective and two transmissive) wavefront manipulation, offering a viable strategy for developing high-performance devices for THz communication, imaging, and encryption systems.