This letter reports on the fabrication, simulation, and characterization of conformal antireflective black-silicon (BSi) nanowires on a 3-D silicon structure. The BSi nanostructures were formed on various facets of a 3-D Si structure including sharp tips and sidewalls using a metal-assisted chemical etching process. The conformal BSi design was simulated using an finite-difference time-domain Lumerical software. The antireflection capability was indicated by the quantified reduction in normalized intensity after the image processing of diffraction patterns. An optical iris of 1.00-mm circular aperture with conformal BSi nanowires was fabricated and characterized to demonstrate the anti-reflectivity capability at two visible wavelengths of 532 and 633 nm. The iris showed a significant reduction in glare around its Airy disc, up to 3x smaller than the same one but without the BSi nanostructures.

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