Terahertz dual-polarization 3-bit coding metasurface based on two pairs of C-shaped split-ring resonators for holographic imaging

Abstract Terahertz holographic imaging based on metasurfaces has attracted increasing attention owing to its promising applications in information storage, image display, and multichannel communication systems. However, realizing 3-bit phase quantization while strictly maintaining low crosstalk between orthogonal polarizations remains a critical bottleneck for high-quality holographic reconstruction. In this paper, a dual-polarized 3-bit coding metasurface is proposed for high-fidelity terahertz holographic imaging. The designed unit cell consists of two pairs of C-shaped split-ring resonators (SRRs), with each pair dedicated to manipulating one specific polarization state. Such a configuration enables independent and flexible control of the reflection phase of incident terahertz waves under two orthogonal polarizations, effectively suppressing cross-polarization interference while ensuring accurate 3-bit phase modulation at 0.9 THz. By employing the Gerchberg–Saxton (GS) algorithm to optimize the coding sequences, the proposed metasurface successfully reconstructs two distinct holographic images under x-polarized and y-polarized excitations, respectively, thereby realizing polarization-multiplexed information encoding. Theoretical analysis and full-wave simulations are in strong agreement, and the reconstructed holographic images achieve a similarity coefficient exceeding 75%. These results demonstrate that the proposed approach provides a feasible solution for high-fidelity terahertz holographic displays and secure information encryption in multiple-input multiple-output (MIMO) systems.