Controllable generation of large-scale highly regular gratings on Si films

• DOI: 10.37188/lam.2021.022
• Publication Date: 2021-08-16T06:15:25Z
• Authors: Jiao Geng; Xiaoguo Fang; Lei Zhang; Guangnan Yao; Liye Xu; Fengjiang Liu; Weiwei Tang; Liping Shi; Min Qiu
• Keywords: 0103 physical sciences; 02 engineering and technology; 0210 nano-technology; 01 natural sciences

The application of femtosecond laser-induced periodic surface texturing has significant potential in medicine, optics, tribology, and biology, among other areas. However, when irradiated by a large intense laser spot, the structures usually exhibit an uncontrollable regularity, forming bifurcated patterns, thus limiting their widespread application. Irregularity originates from numerous independent branching seeds. usual solution to this problem is utilize quasi-direct writing technique, that is, beam size (diameter <10 wavelengths) scanning or samples using 2D translation stages. Herein, we demonstrate optical localization-induced nonlinear competition mechanism solve problem, which occurs at fluence nearly one order magnitude below ablation threshold. Owing low intrinsic absorption silicon ultralow applied fluence, ensures self-selection single seed initiate array bifurcated-free gratings under stationary irradiation with spot >100 wavelengths). Surprisingly, some unconventional complex such as radial, annular, spiral gratings, can also be easily produced structured light fields unprecedented regularity. Their diameters reach up >500 μm. Moreover, artificially control initial seeding structure further improve regularity defined dispersion ripple orientation angle Fourier transform. As result, our experiments even higher than scanned tiny beam. Controllable highly regular ripples are beneficial structural coloring effects because they arise diffraction subwavelength gratings.