Dual-band giant spin-selective full-dimensional manipulation of graphene-based chiral meta-mirrors for terahertz waves

TLDR

Simultaneous circular dichroism and wavefront manipulation are crucial for detection and imaging, yet existing chiral nanostructures are limited by complex 3D designs, narrow‑band response, and lack of tunability, hindering integration and miniaturization. The authors propose a bi‑layer all‑graphene meta‑mirror platform that, through hybridization coupling, simultaneously delivers giant dual‑band circular dichroism and wavefront shaping. By tuning structural variables and graphene parameters—combining passive and active control—the design selectively modulates polarization, amplitude, phase, and frequency of incident circularly polarized terahertz waves, enabling dynamic wavefront shaping and near‑field digital imaging with high tunability. The resulting meta‑mirrors exhibit high‑performance dynamic tunability for terahertz wavefront shaping and near‑field imaging, providing new options for next‑generation intelligent terahertz communication systems.

Abstract

The ability to simultaneous achieve circular dichroism (CD) and wavefront manipulation is extremely important for many practical applications, especially for detecting and imaging. However, many of the previously observed weakness chiral features are limited to nanostructures with complex three-dimensional building configurations, single narrow-band response, and no active tunability, which are getting farther and away from the goal of integration and miniaturization. Here, a platform of bi-layer all-graphene meta-mirrors with spin-selective full-dimensional manipulation is proposed to simultaneously achieve giant dual-band CD response and wavefront shaping, based on the principle of the hybridization coupling. By simply controlling the structural variables of the meta-mirror and the characteristic parameters of graphene, that is, the combination of passive and active regulation, the proposed design can selectively manipulate the polarization, amplitude, phase, and working frequency of the incident circularly polarized wave near-independently. As a proof of concept, we used the meta-mirror to design two metasurface arrays with spin-selective properties for dynamic terahertz (THz) wavefront shaping and near-field digital imaging, both of which show a high-performance dynamic tunability. This method could provide additional options for the next-generation intelligent THz communication systems.