Broadband communication with high data rates is a dire need for state-of-the-art wireless technologies. For achieving efficient wireless communication (particularly in an indoor environment), the electromagnetic (EM) waves should maintain their state of polarization despite encountering multiple reflections. Metasurfaces provide a unique platform to design subwavelength-featured meta-reflectarrays which enable the desired retention of the polarization state of an EM wave upon reflection. We present a single-layered broadband meta-reflectarray, simultaneously breaking n-fold (n > 2) rotational and mirror symmetry, which exhibits an unprecedented control over the phase, amplitude, and polarization of a reflected EM wave. This unique control enables the retention of polarization state and recording of spin-encrypted information for the reflected EM waves. Such novel multifunctional meta-reflectarray can be crucial to building an indoor setup for high data rate wireless communications. Meanwhile, the meta-array’s ability to encode phase information provides an extra degree of freedom to structure and control (via incident spin) the reflected EM beam in the desired way. For the proof of concept, we have experimentally demonstrated a spin-encrypted holographic display which reconstructs the recorded holographic image at an image plane for the left circularly polarized (LCP) illumination and exhibits circular dichroism for the right circularly polarized (RCP) incident waves. The proposed meta-array can find applications in 5G indoor wireless communication, chiral sensing, spin-selective imaging, holography, and encryption.

中文翻译：

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用于极化保持和自旋加密相位编码的单层元反射阵列

迫切需要最新的无线技术来实现高数据速率的宽带通信。为了实现有效的无线通信（尤其是在室内环境中），尽管遇到多次反射，电磁波（EM）仍应保持其极化状态。超颖表面提供了一个独特的平台来设计亚波长特征的超反射阵列，该阵列可使反射后的EM波的偏振态保持所需的状态。我们提出了一种单层宽带元反射阵列，同时打破了n折（n> 2）旋转和镜像对称，这对反射的EM波的相位，幅度和极化表现出空前的控制。这种独特的控制可以保留极化状态并记录反射的EM波的自旋加密信息。这种新颖的多功能元反射阵列对于建立用于高数据速率无线通信的室内设置至关重要。同时，元阵列对相位信息进行编码的能力提供了额外的自由度，以所需的方式构造和控制（通过入射自旋）反射的EM光束。为了证明这一点，我们已通过实验证明了一种自旋加密的全息显示器，该显示器可在左旋圆偏振（LCP）照明的像面上重建记录的全息图像，并在右旋圆偏振（RCP）入射波中表现出圆二色性。提出的元阵列可以在5G室内无线通信，手性传感，自旋选择成像，全息术和加密中找到应用。