Achieving broadband multifunctional modulation of wavefront via terahertz anisotropic metasurface

• A bilayer anisotropic VO 2 metasurface is proposed, enabling four-function wavefront modulation through a simple approach. • Four channels of metasurface can be altered by adjusting the state of VO 2 and the polarization direction of incident wave. • The metasurface exhibits the outstanding ability of wavefront modulation within the wide frequency range of 2.2–3.0 THz. Vanadium dioxide (VO 2 ) has become a reliable phase change material (PCM) and is increasingly utilized in multifunctional metasurface design. This study introduces designs of bilayer anisotropic VO 2 meta -atoms in simulation for multifunctional wavefront modulation in the terahertz band. By leveraging the phase change property of VO 2 and incident wave polarization, a reconfigurable metasurface composing anisotropic meta -atoms is proposed with four distinct functions. When VO 2 is in its insulating state, the metasurface serves as a hologram generator for the x-polarized wave and a focusing reflector for the y-polarized wave. Upon the transition of VO 2 into the metallic state, the metasurface functions as a generator of vortex beam for the x-polarized wave, while as an anomalous reflector for the y-polarized wave. The proposed metasurface showcases an outstanding broadband performance, delivering impressive four-channel wavefront modulation within a frequency range of 2.2–3.0 THz. Depending on the compact structure and integrated multi-functionalities, our design may have immense potential across a wide range of terahertz applications, including communication exchange and multiplexing utilization.