Designed micro-nano structures on the surface of aluminum alloy provide excellent light trapping properties that can be used extensively in thermal photovoltaics, sensors, etc. However, the fabrication of high-performance antireflective micro-nano structures on aluminum alloy is challenging because aluminum has shallow intrinsic losses and weak absorption. A two-step strategy is proposed for fabricating broadband antireflection structures by superimposing nanostructures onto microscale structures. By optimizing the processing parameters of femtosecond laser, the average reflectances of 2.6% within the visible spectral region (400–800 nm) and 5.14% within the Vis-NIR spectral region (400–2500 nm) are obtained.

Mitigating the optical reflection of aluminum alloy over a broad spectral range from 0.45 μm to 15 μm is vital for many applications. This can be realized by introducing efficient light-absorbing textured surfaces via femtosecond laser surface processing. However, a clear analysis of antireflection performance has not been reported yet. This paper proposes a numerical model of anti-reflective structures is proposed based on SEM and EDS characterization. Multiple anti-reflective mechanisms were revealed intuitively through FDTD simulation.