Multiscale Hierarchical Micro/Nanostructures Created by Femtosecond Laser Ablation in Liquids for Polarization-Dependent Broadband Antireflection.

摘要: In this work, we present the possibility of producing multiscale hierarchical micro/nanostructures by femtosecond laser ablation transition metals (i.e., Ta and W) in water investigate their polarization-dependent reflectance. The are composed microscale-grooved, mountain-like pit-rich structures decorated with hybrid laser-induced periodic surface (LIPSSs). LIPSSs consist low/high ultrahigh spatial frequency (LSFLs/HSFLs UHSFLs). LSFLs/HSFLs 400-600 nm a period typically oriented perpendicular to direction polarization, while UHSFLs (widths: 10-20 periods: 30-50 nm) curvatures LSFLs/HSFLs. On microstructures height gradients, orientations misaligned 18°. ablated W metasurface, two kinds observed. become parallel nanowires deep troughs but result being very chaotic shallow LSFLs, turning into polygonal nanonetworks. contrast, USFLs not found on metasurfaces. With help Fourier transform infrared spectroscopy, it is that microgrooves show an obvious reflectance at wavelengths 15 17.5 μm associated groove, integration LSFs/HSFLs/UHSFLs thus beneficial for enhancing light absorbance trapping near-to-mid-infrared (NIR-MIR) range.