Transmissive all-dielectric metasurfaces for reconstructing terahertz holographic images via polarization-multiplexing and polarization-decoupling

Recently, the multifunctional terahertz metasurface holography (meta-holography) has garnered significant attention and sparked wide discussions due to its capacity for carrying a large amount of information. However, traditional multifunctional meta-holography, achieved by integrating metasurfaces with active materials or MEMS technology, have exhibited distinct shortcomings due to their intrinsic properties, such as slow response, complex structure, or low reliability. Herein, we propose a transmissive metasurface platform composed of anisotropic all-dielectric meta-atoms including three parts: the elliptical silicon pillars (Si-pillars), circular Si-pillars, and a quartz substrate sandwiched between them. This platform enables the implementation of dual-channel holographic images by utilizing linear polarization (LP) multiplexing and circular polarization (CP) decoupling. As proof of concept, two transmissive anisotropic metasurfaces (MS-1 and MS-2) are designed and created. When illuminated with two orthogonal LP-polarization waves, the MS-1 can produce holographic images of the letters 'X' and 'Y' in the corresponding co-polarized channel. Additionally, the MS-2 is illuminated by the left-circularly polarized (LCP) wave, two holographic images with different patterns ('L' and 'R') are reconstructed in the co-polarized and cross-polarized channels respectively. Therefore, the proposed metasurfaces allowing for polarization-multiplexing or polarization-decoupling can exhibit considerable potential for applications in multifunctional integration and high information capacity.