Multifunctional manipulation of terahertz waves using vanadium-dioxide-based metagratings

Metasurfaces with phase-change materials have provided a promising way to achieve switchable and diverse wave control at terahertz (THz) frequencies. However, most of these reconfigurable metasurfaces are designed by complex structures that are challenged by the experimental feasibility. Here we propose a simple metagrating structure made of vanadium dioxide to realize reconfigurable manipulation of THz waves. Different from previous works, an inverse-design method is adopted to construct the metagrating, which enables multifunctional and switchable wave functions of THz waves including the switch between a perfect retroreflector and a high-efficiency absorber, polarization beam splitter, and linear polarizer. Our work provides a neat and effective method to achieve reconfigurable and multifunctional wave phenomena in a single meta-device, which may find applications in polarization control, remote sensing, and object detection.