Superscattering, that is, a phenomenon of the scattering cross section from a subwavelength object exceeding the single-channel limit, has important prospects in enhanced sensing/spectroscopy, solar cells, and biomedical imaging. Superscattering can be typically constructed only at a single frequency regime, and depends critically on the inescapable material losses. Under such realistic conditions, superscattering has not been predicted nor observed to exist simultaneously at multiple frequency regimes. Here we introduce multifrequency superscattering in a subwavelength hyperbolic structure, which can be made from artificial metamaterials or from naturally existing materials, such as hexagonal boron nitride (BN), and show the advantage of such hyperbolic materials for reducing structural complexity. The underlying mechanism is revealed to be the multimode resonances at multiple frequency regimes as appear in BN due to the peculiar dispersion of phonon-polaritons. Importantly, the multifrequency superscattering has a high tolerance to material losses and some structural variations, bringing the concept of multifrequency superscattering closer to useful and realistic conditions.

中文翻译：

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亚波长双曲结构的多频超散射

超散射，即来自亚波长物体的散射截面超过单通道极限的现象，在增强的感测/光谱学，太阳能电池和生物医学成像中具有重要的前景。超散射通常只能在单个频率范围内构建，并且严重取决于不可避免的材料损失。在这种现实条件下，没有预测也没有观察到在多个频率范围内同时存在超散射。在这里，我们介绍了亚波长双曲线结构中的多频超散射，该结构可以由人工超材料或天然存在的材料（例如六方氮化硼（BN））制成，并展示了此类双曲线材料在降低结构复杂性方面的优势。由于声子-极化子的奇特色散，揭示了潜在的机制是在BN中出现的多个频率范围的多模共振。重要的是，多频超级散射对材料损失和某些结构变化具有很高的容忍度，使多频超级散射的概念更接近有用和现实的条件。