It is very challenging to achieve near perfect absorption or emission that is both broadband and omnidirectional while utilizing a scalable fabrication process. Femtosecond laser surface processing is an emerging low-cost and large-scale manufacturing technique used to directly and permanently modify the surface properties of a material. The versatility of this technique to produce tailored surface properties has resulted in a rapidly growing number of applications. Here, we demonstrate near perfect, broadband, omnidirectional emissivity from aluminum surfaces by tuning the laser surface processing parameters including fluence, pulse count, and the ambient gas. Full-wave simulations and experimental results prove that the obtained increase in emissivity is mainly a result of two distinct features produced by femtosecond laser surface processing: the introduction of microscale surface features and the thick oxide layer. This technique leads to functionalized metallic surfaces that are ideal for emerging applications, such as passive radiative cooling and thermal management of spacecraft.

在利用可扩展的制造工艺时，要获得宽带和全向的近乎完美的吸收或发射是非常具有挑战性的。飞秒激光表面处理是一种新兴的低成本，大规模制造技术，用于直接和永久地更改材料的表面特性。这种技术可产生定制的表面性能，因此用途广泛。在这里，我们通过调整激光表面处理参数（包括注量，脉冲数和环境气体）来演示铝表面近乎完美的宽带全向发射率。全波仿真和实验结果证明，发射率的提高主要是飞秒激光表面处理产生的两个明显特征的结果：引入微观尺度的表面特征和厚氧化层。这种技术导致功能化的金属表面非常适合新兴应用，例如被动辐射冷却和航天器的热管理。