Strongly anisotropic media where the principal components of electric permittivity or magnetic permeability tensors have opposite signs are termed as hyperbolic media. Such media support propagating electromagnetic waves with extremely large wave vectors exhibiting unique optical properties. However, in all artificial and natural optical materials studied to date, the hyperbolic dispersion originates solely from the electric response. This restricts material functionality to one polarization of light and inhibits free-space impedance matching. Such restrictions can be overcome in media having components of opposite signs for both electric and magnetic tensors. Here we present the experimental demonstration of the magnetic hyperbolic dispersion in three-dimensional metamaterials. We measure metamaterial isofrequency contours and reveal the topological phase transition between the elliptic and hyperbolic dispersion. In the hyperbolic regime, we demonstrate the strong enhancement of thermal emission, which becomes directional, coherent and polarized. Our findings show the possibilities for realizing efficient impedance-matched hyperbolic media for unpolarized light.

中文翻译：

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磁性双曲光学超材料。

介电常数或磁导率张量的主要成分具有相反符号的强各向异性介质称为双曲线介质。这样的介质以极大的波矢量支持传播的电磁波，这些波矢量表现出独特的光学特性。然而，在迄今为止研究的所有人造和天然光学材料中，双曲线色散仅源自电响应。这将材料功能性限制为光的一种偏振，并抑制了自由空间阻抗匹配。在具有用于电和磁张量的相反符号的组件的介质中，可以克服这种限制。在这里，我们介绍三维超材料中的磁双曲线弥散的实验演示。我们测量了超材料等频线轮廓，并揭示了椭圆形和双曲线色散之间的拓扑相变。在双曲状态下，我们证明了热发射的强烈增强，该热发射变成定向的，相干的和极化的。我们的发现表明了为非偏振光实现高效阻抗匹配双曲线介质的可能性。