We present a polarization-insensitive metasurface processor to perform spatial asymmetric filtering of an incident beam, thereby allowing for real-time parallel analog processing. To enable massive parallel processing, we introduce a multiple-input multiple-output (MIMO) computational metasurface with asymmetric response that can perform spatial differentiation on two distinct input signals regardless of their polarization. In our scenario, two distinct signals set in $x$ and $y$ directions, parallel and perpendicular to the incident plane, illuminate simultaneously the metasurface processor, and the resulting differentiated signals are separated from each other via appropriate spatial low-pass filters. By leveraging generalized sheet transition conditions and surface susceptibility tensors, we design an asymmetric meta-atom augmented with normal susceptibilities to reach asymmetric response at normal beam illumination. Proof-of-principle simulations are also reported along with the successful realization of signal processing functions. The proposed metasurface overcomes major shortcomings imposed by previous studies, such as large architectures arising from the need for additional subblocks, slow responses, and, most importantly, supporting only a single input with a given polarization. Our results set the path for future developments of material-based analog computing using efficient and easy-to-fabricate MIMO processors for compact, fast, and integrable computing elements without any Fourier lens.

中文翻译：

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基于a2×2非对称响应的多输入多输出超表面处理器的并行模拟计算

我们提出一种对极化不敏感的超表面处理器，以对入射光束进行空间非对称滤波，从而实现实时并行模拟处理。为了实现大规模并行处理，我们引入了具有非对称响应的多输入多输出（MIMO）计算超表面，该超表面可以对两个不同的输入信号进行空间微分，而无论其极化如何。在我们的场景中，设置了两个不同的信号$X$ 和 $ÿ$平行于入射平面并垂直于入射平面的两个方向同时照射超表面处理器，并且所产生的微分信号通过适当的空间低通滤波器彼此分离。通过利用广义的薄片转变条件和表面磁化张量，我们设计了一个不对称的偏原子，该原子以正常的磁化率增强，从而在正常的光束照射下达到不对称的响应。还报告了原理证明仿真以及信号处理功能的成功实现。所提出的超颖表面克服了先前研究所施加的主要缺点，例如由于需要更多子块，响应速度较慢而产生的大型体系结构，最重要的是，仅支持具有给定极化的单个输入。