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.
Keywords: aluminum alloy; antireflection; femtosecond laser; surface micro/nanostructure.