Carbonized Hybrid Micro/Nanostructured Metasurfaces Produced by Femtosecond Laser Ablation in Organic Solvents for Biomimetic Antireflective Surfaces

Hybrid micro/nanostructures and light-absorbing pigment of melanin are two key factors for the excellent antireflective properties of the butterfly wings of Ornithoptera goliath. In this work, femtosecond laser ablation of metals in an organic solvent (FLAMOS) was used to generate hybird micro/nanostructured cross-linked ultrahigh/low spatial frequency laser-induced periodic surface structures (UHSFLs/LSFLs), which well mimic the antireflective architecture of Ornithoptera goliath. The simultaneously deposited carbon or newly formed transition metal carbide (TMC) plays the same role of light-absorbing pigment of melanin on Ornithoptera goliath. A total of 13 transition metals and one transition-metal alloy (Ti, V, Nb, Ta, Mo, W, Fe, Pd, Pt, Ni, Au, Ag, Cu, and CuZn) were systematically investigated by FLAMOS to demonstrate the material-dependent formation of cross-linked hybrid UHSFL/LSFL nanostructures and metal carbonization. Hybrid UHSFLs/LSFLs were only found to be achievable when using group IVB-VIB transition metals (e.g., Ti, V, Nb, Ta, Mo, and W), while LSFLs and hole-rich microstructures were obtained with group VIII (e.g., Fe, Pd, Pt, and Ni) and IB/IB-IIB (e.g., Au, Ag, Cu, and CuZn) transition metals or alloy. This work represents the first-ever demonstration that the orientations of UHSFLs are perpendicular to the curvatures of LSFLs because of Marangoni bursting rather than parallel to the direction of light polarization, as is commonly thought to be the case. The surface chemistry and exceptional multioptical properties of structured metasurfaces were assessed, including thermally resistant antireflectance in the UV-near-infrared (NIR) range, enhanced selective absorbance in the NIR-mid-IR (MIR) range, and polarization-dependent NIR-MIR reflectance. Synergistic effects from TMCs/carbon networks and surface nanostructures resulted in the reflectance of Fe, CuZn, Ni, Ta, Mo, Ti, V, Nb, and W metasurfaces below 1% in the UV-NIR range (less than 0.2% over the entire UV-NIR range for Ni, Ti, V, and W metasurfaces).