Nonreciprocal thermal radiation allows the violation of Kirchhoff's law, as the spectral directional emissivity and absorptivity at the same angle can be different. Prior research has elucidated that certain optical resonance modes facilitate amplification of nonreciprocity at specific angles or wavelengths. However, achieving nonreciprocal thermal radiation with both wide-angle coverage and narrowband characteristics poses a fundamental yet challenging problem. In this work, we demonstrate a nonreciprocal thermal emitter that achieves both wide-angle and narrowband through a periodic structure composed of magneto-optical materials. With an external magnetic field ( = 3 T or 1 T), the pronounced nonreciprocity arising from the magneto-optical localized resonance mode at 6.52 μm or 7.18 μm facilitates a distinct difference between the emissivity and absorptivity across a wide angular range from near 0°–89°. The robustness of the wide-angle and narrowband nonreciprocal thermal radiation is demonstrated with ±5 % fluctuations in structural parameters. The performance of the nonreciprocity with azimuthal angle ranging from 0° to 360° is also investigated. This work holds promising potential for applications in thermal management, directional thermal camouflage, high-efficiency thermophotovoltaic systems, and more.

中文翻译：

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非互易广角和窄带热发射器


非互易热辐射允许违反基尔霍夫定律，因为同一角度的光谱定向发射率和吸收率可能不同。先前的研究已经阐明，某些光学共振模式有助于在特定角度或波长下放大非互易性。然而，实现具有广角覆盖和窄带特性的不可逆热辐射提出了一个基本但具有挑战性的问题。在这项工作中，我们展示了一种不可逆热发射器，它通过磁光材料组成的周期性结构实现广角和窄带。在外部磁场（= 3 T 或 1 T）下，6.52 μm 或 7.18 μm 处的磁光局域共振模式产生的明显非互易性，使得发射率和吸收率在从接近 0° 的宽角度范围内出现明显差异–89°。广角和窄带非互易热辐射的鲁棒性通过结构参数 ±5% 的波动得到证明。还研究了方位角范围从 0° 到 360° 的非互易性的性能。这项工作在热管理、定向热伪装、高效热光伏系统等领域具有广阔的应用前景。