Independent Control of Beam Direction and Polarization of Terahertz Active Wavefronts with Cascaded Metasurfaces

Terahertz (THz) wave front control technologies have recently attracted huge attention due to their potential applications in THz radar, communication and imaging system. According to Huygens principle, the manipulation of wavefront requires local control of the phase of the propagation source. However, in the THz regime, such local phase modulation is hampered by that current electronic device (such as PIN diodes or variable capacitors, widely used in Microwave regime) are unavailable in terahertz regime. Here, we propose a novel terahertz wave front control mechanism based on four cascaded metasurfaces, which can control the direction and polarization of beam by rotating angles of four cascaded Metasurface separately. Our design of terahertz device provides a new approach for the implementation of easy-to-fabricate beam-scanning and polarization-conversion devices in THz regime.