Scattering of electromagnetic waves lies at the heart of most experimental techniques over nearly the entire electromagnetic spectrum, ranging from radio waves to optics and X-rays. Hence, deep insight into the basics of scattering theory and understanding the peculiar features of electromagnetic scattering is necessary for the correct interpretation of experimental data and an understanding of the underlying physics. Recently, a broad spectrum of exceptional scattering phenomena attainable in suitably engineered structures has been predicted and demonstrated. Examples include bound states in the continuum, exceptional points in PT-symmetrical non-Hermitian systems, coherent perfect absorption, virtual perfect absorption, nontrivial lasing, non-radiating sources, and others. In this paper, we establish a unified description of such exotic scattering phenomena and show that the origin of all these effects can be traced back to the properties of poles and zeros of the underlying scattering matrix. We provide insights on how managing these special points in the complex frequency plane provides a powerful approach to tailor unusual scattering regimes.

中文翻译：

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光散射异常

电磁波的散射是几乎整个电磁波谱中大多数实验技术的核心，范围从无线电波到光学和 X 射线。因此，深入了解散射理论的基础知识和理解电磁散射的特殊特征对于正确解释实验数据和理解基础物理是必要的。最近，已经预测并证明了在适当设计的结构中可以获得的广泛的特殊散射现象。示例包括连续介质中的束缚态、PT 对称非厄米系统中的异常点、相干完美吸收、虚拟完美吸收、非平凡激光、非辐射源等。在本文中，我们建立了对这种奇异散射现象的统一描述，并表明所有这些效应的起源都可以追溯到底层散射矩阵的极点和零点的特性。我们提供了有关如何管理复杂频率平面中的这些特殊点提供了一种定制异常散射机制的强大方法的见解。