The ability to control the directional and spectral properties of thermal emission is of fundamental importance for many applications. Here we propose a method to design directional and broadband thermal emitters (DBTEs) and directional and narrowband thermal emitters (DNTEs) based on classic thermal emitters and angular selectors. DBTEs exhibit strong thermal emission at a specific angle and within a broadband wavelength range. Besides, DBTEs achieve better radiative cooling performance than classic thermal emitters without special angular control when there are surrounding buildings. On the other hand, DNTEs can confine thermal emission within a narrow bandwidth and a narrow angular width. DNTEs show higher energy conversion efficiency than conventional narrowband thermal emitters, and have potential application in high-efficiency infrared light sources.

中文翻译：

---

辐射的方向和光谱控制及其在辐射冷却和红外光源中的应用

控制热辐射的方向和光谱特性的能力对于许多应用至关重要。在此，我们提出了一种基于经典热辐射器和角度选择器的定向和宽带热辐射器（DBTE）以及定向和窄带热辐射器（DNTE）的设计方法。DBTE在特定角度和宽带波长范围内均显示出强烈的热辐射。此外，在建筑物周围的情况下，DBTE可以比传统的热辐射器实现更好的辐射冷却性能，而无需特殊的角度控制。另一方面，DNTE可以将热辐射限制在窄带宽和窄角宽度内。DNTE比传统的窄带热辐射器具有更高的能量转换效率，