The accidental Dirac cone of a photonic crystal allows the realization of a low loss dielectric metamaterial with simultaneous near-zero effective permittivity and permeability. The resulting zero refractive index allowed applications that require unique spatial coherency. While most thermal light sources were considered highly incoherent, structurally engineered thermal emitters have achieved relatively high spatial coherency. Here, we propose an epsilon-and-mu-near-zero metamaterial as a spatial coherency converter for thermal emissions, and experimentally demonstrate surface-normal directional emissions with an angular width of 20 degrees.

中文翻译：

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基于 Epsilon-and-mu-near-zero 超材料的部分空间相干热发射器

光子晶体的偶然狄拉克锥允许实现低损耗介电超材料，同时有效介电常数和磁导率接近零。由此产生的零折射率允许需要独特空间相干性的应用。虽然大多数热光源被认为是高度不相干的，但结构设计的热发射器已经实现了相对较高的空间相干性。在这里，我们提出了一种 epsilon-and-mu-near-zero 超材料作为热发射的空间相干转换器，并通过实验证明了角宽度为 20 度的表面法向定向发射。