In this paper, we demonstrate the fabrication of S-shaped micron-sized constrictions on steel (Fe₃C_II) surface using the femtosecond laser ablation technique. The femtosecond laser used has a wavelength of 775 nm, a power range of 0–1000 mW, a pulse duration of 130 fs, and a pulse repetition rate of 1–2 kHz. The ultra-low-pulse duration of 130 fs enables ablation of material surfaces without excessive thermal heating of the material around the zone of ablation. This becomes useful when ablating materials that are thermally sensitive such as superconducting thin films. This practice run of ablating S-shaped micron-sized constrictions on steel surfaces shown in this paper will enable one to use the same technique in ablating micron- and nano-sized structures on superconducting thin films without thermally altering the superconductive film. In this paper, S-shaped micron-sized constrictions on steel were fabricated with a constriction width of 37.1 and 47.3 μm whose images were created using an optical microscope (OM) and S-shaped micron-sized constrictions with a constriction width of 30.8 and 35.2 μm whose images were created using an atomic force microscope (AFM). The reduction in the constriction widths was achieved by reducing the laser ablation width or laser ablation spot size and then bringing the laser ablation spots closer together in G-code program. The reduction of the laser ablation width is achieved by reducing the laser fluence applied closer to the ablation threshold of steel and by using laser beam shaping techniques such as beam collimation and beam focusing.

在本文中，我们展示了在钢 ( Fe ₃ C _II) 表面使用飞秒激光烧蚀技术。所使用的飞秒激光器波长为 775 nm，功率范围为 0-1000 mW，脉冲持续时间为 130 fs，脉冲重复率为 1-2 kHz。130 fs 的超低脉冲持续时间能够对材料表面进行烧蚀，而不会对烧蚀区域周围的材料产生过多的热加热。这在烧蚀对热敏感的材料（例如超导薄膜）时非常有用。本文中显示的这种在钢表面上烧蚀 S 形微米级收缩的实践运行将使人们能够使用相同的技术在超导薄膜上烧蚀微米级和纳米级结构，而无需热改变超导膜。在本文中，在钢上制造了 S 形微米尺寸的缩颈，缩颈宽度为 37。1 和 47.3 μm 的图像是使用光学显微镜 (OM) 创建的，S 形微米尺寸的缩颈宽度为 30.8 和 35.2 μm，其图像是使用原子力显微镜 (AFM) 创建的。通过减小激光烧蚀宽度或激光烧蚀光斑尺寸，然后在 G 代码程序中使激光烧蚀光斑靠得更近来实现收缩宽度的减小。激光烧蚀宽度的减小是通过减少更接近钢烧蚀阈值的激光能量密度和使用激光束整形技术（如光束准直和光束聚焦）来实现的。2 μm，其图像是使用原子力显微镜 (AFM) 创建的。通过减小激光烧蚀宽度或激光烧蚀光斑尺寸，然后在 G 代码程序中使激光烧蚀光斑靠得更近来实现收缩宽度的减小。激光烧蚀宽度的减小是通过减少更接近钢烧蚀阈值的激光能量密度和使用激光束整形技术（如光束准直和光束聚焦）来实现的。2 μm，其图像是使用原子力显微镜 (AFM) 创建的。通过减小激光烧蚀宽度或激光烧蚀光斑尺寸，然后在 G 代码程序中使激光烧蚀光斑靠得更近来实现收缩宽度的减小。激光烧蚀宽度的减小是通过减少更接近钢烧蚀阈值的激光能量密度和使用激光束整形技术（如光束准直和光束聚焦）来实现的。