Full-space metasurfaces demonstrate powerful abilities in manipulating electromagnetic (EM) waves, but most of them are usually single band. Here, a multiband bidirectional digital coding metasurface is proposed for multiple tasks, which can achieve completely different functions in up to six frequency bands when the EM waves are incident from the front and back of the metasurface. As a proof-of-concept, we design and fabricate a dual-band full-space metasurface with integrated functions of reflection, transmission, holographic imaging, and vortex-beam forming, and a six-band full-space metasurface with completely independent holographic imaging functions at different frequency bands. Simulated and measured results are in good agreements with the theoretical predictions, verifying the good performance of the proposed multitask bidirectional digital coding metasurface.

中文翻译：

---

多任务双向数字编码超表面，用于独立控制多波段和全空间电磁波

全空间超表面在操纵电磁 (EM) 波方面表现出强大的能力，但它们中的大多数通常是单波段的。在这里，针对多个任务提出了一种多波段双向数字编码超表面，当电磁波从超表面的正面和背面入射时，它可以在多达六个频带内实现完全不同的功能。作为概念验证，我们设计并制造了具有反射、透射、全息成像和涡旋光束形成功能的双波段全空间超表面，以及具有完全独立全息的六波段全空间超表面。不同频段的成像功能。模拟和实测结果与理论预测吻合较好，