Terahertz cascaded metasurfaces for both spin-symmetric and asymmetric beam diffractions with active power distribution

Ultra-compact and tunable devices for terahertz (THz) beam manipulation are highly desired in wireless communication radar scanning. Although the appearance of Pancharatnam-Berry (PB) metasurface has provided strategies THz scanning, active output power distribution is still difficult to achieve, flexibility limited by a single metasurface. In this work, we demonstrated an all-dielectric cascaded consisting spin-decoupled PB The conjugated characteristic phase two photonic spin states broken with efficient high-order diffractions wave vector superposition through metasurfaces, both spin-symmetric spin-asymmetric transmissions obtained designing differences bandwidth. Moreover, between deflection beams can be actively tuned changing incident polarization state, achieving modulation ratios 99.3% 95.1% beams, respectively. Therefore, work realizes controllable division multiplexing opens new avenues design ultra-compact multifunctional devices.