Creating a three-dimensional surface with antireflective properties by using femtosecond-laser Bessel-beam-assisted thermal oxidation

Metal surfaces with low reflectance have received considerable attention for their great optical, electrical, and thermal properties. However, the difficulty in achieving low reflectance on curved metal surfaces has hindered their practical applications. We propose a rapid and flexible method for processing a three-dimensional surface with antireflective properties. A Bessel beam created using an axicon is employed to generate ripple structures on the curved surface, thereby assisting subsequent thermal oxidation. Ripple structures coated with oxide semiconductor nanowires are then processed on a Cu substrate, thus further reducing reflectance. Antireflective properties with a minimum reflectance of less than 0.015 at a wavelength of 500-1200 nm could be achieved by using this method. This presented approach reduces dimensionality in laser processing, subsequently improving processing efficiency, and provides a foundation for the practical application of metal antireflective surfaces.