Exceptional points, as degenerate points of non-Hermitian parity-time symmetric systems, have many unique physical properties. Due to its flexible control of electromagnetic waves, a metasurface is frequently used in the field of nanophotonics. In this work, we developed a parity-time symmetric metasurface and implemented the 2π$2\pi$ topological phase surrounding an exceptional point. Compared with Pancharatnam-Berry phase, the topological phase around an exceptional point can achieve independent regulation of several circular polarization beams. We combined the Pancharatnam-Berry phase with the exceptional topological phase and proposed a composite coding metasurface to achieve reflection decoupling of different circular polarizations. This work provides a design idea for polarimetric coding metasurfaces in the future.

中文翻译：

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通过特殊的拓扑相位编码超表面独立控制圆偏振光

例外点作为非厄米宇称时间对称系统的简并点，具有许多独特的物理性质。由于其对电磁波的灵活控制，超表面经常被应用于纳米光子学领域。在这项工作中，我们开发了一种宇称时间对称超表面，并实现了围绕异常点的2 π拓扑相位。$2\pi$与Pancharatnam-Berry相相比，特异点周围的拓扑相可以实现多个圆偏振光束的独立调节。我们将 Pancharatnam-Berry 相与特殊的拓扑相相结合，提出了一种复合编码超表面，以实现不同圆偏振的反射解耦。这项工作为未来偏振编码超表面提供了一种设计思路。