Terahertz Multi‐State Reconfigurable Holographic Metasurface Based on Full‐Stokes Magnetic Eigen‐Modulation of Photonic Weyl Semimetal

The metasurface is limited by the fixed microstructure to integrate more reconfigurable functional states, making it indispensable to introduce active materials. Nowadays, attributing to the nontrivial topological properties, the photonic Weyl semimetal shows its potential in active polarization modulation. Here, it is demonstrated that the photonic Weyl semimetal can filter the light with arbitrary required normalized Stokes parameters selected by the magnetic field, namely full-Stokes magnetic eigen-modulation scheme, and an analytical relationship between the magnetized direction and eigen polarization state is further derived to guide the modulation scheme. The fractional bandwidth of the modulation scheme is up to 52%. Combined with vectorial holography, an 8-state reconfigurable metasurface is designed, whose imaging states can be modulated by magnetized direction and experimentally demonstrated in the frequency range from 0.6 to 0.71THz. Furthermore, a single metasurface can function as four switches of the four pairs of orthogonal polarization channels, and the largest contrast ratios of each state are over 18 dB. This multi-state metasurface scheme provides a novel paradigm to increase the number of functional states, theoretically to infinity, showing promising potential in 6G THz communication and quantum technology.