All-silicon terahertz dielectric metasurface with polarization and phase decoupling modulation

All-dielectric chiral metasurfaces, as an emerging micro-nano optics device, have been favored in the fields of encrypted communication and optical device integration in recent years due to the strong circular dichroism (CD) and spinning effect at tiny sizes. However, a critical challenge is to achieve decoupled modulation for polarization and phase of the circularly polarized light (CPL) within a single all-dielectric unit. Here, an all-dielectric metasurface capable of simultaneously modulating polarization and phase is constructed, inspired by the art of military formation and deployment in ancient China. This methodology initiates with chiral isomer pairs of meta-atoms combined into “unit corps”. Polarization rotation is achieved through rotational manipulation of individual chiral meta-atoms within the “unit corps”, subsequently incorporating geometric phase modulation between adjacent “unit corps” to enable precise wavefront phase control. This approach effectively bypasses the inherent obstacle of polarization and phase decoupled modulation, enabling the completion of plane-wave wavefront shaping while maintaining 92% polarization conversion efficiency. The developed structural configuration establishes a novel platform for multi-parameter manipulation, providing critical insights for advancing chiroptical metasurface engineering.