Large area laser-induced periodic surface structures on steel by bursts of femtosecond pulses with picosecond delays. (March 2019)

• Record Type: Journal Article
• Authors: Giannuzzi, Giuseppe; Gaudiuso, Caterina; Franco, Cinzia Di; Scamarcio, Gaetano; Lugarà, Pietro Mario; Ancona, Antonio
• Is Part Of: Optics and lasers in engineering. Volume 114(2019)
• Page Start: 15
• Page End: 21
• Publication Date: 2019-03
• Subjects: Laser structuring -- Nanostructures -- Laser-induced periodic surface structures -- Femtosecond laser -- Burst -- Metals; Lasers in engineering -- Periodicals; Optical measurements -- Periodicals; Optics -- Periodicals; Lasers en ingénierie -- Périodiques; Mesures optiques -- Périodiques; Optique -- Périodiques; 621.36605
• DOI: 10.1016/j.optlaseng.2018.10.006
• Languages: English
• ISSNs: 0143-8166

Abstract

Highlights: Regular patterns of nanoripples produced by bursts of fs laser pulses with ps delay. The spatial frequency and depth of the nanoripples depends on the burst features. For bursts with two sub-pulses the spatial period increases with the delay. The ripples depth decreases with the intraburst delay due to a plasma shielding. Plasma shielding is compensated by incubation for higher number of sub-pulses. Abstract: Bursts of linearly polarised femtosecond laser pulses with variable intra-burst delays on the picosecond timescale and different number of sub-pulses were used to produce laser-induced periodic surface structures (LIPSS) on stainless steel surfaces. The influence on the LIPSS morphology of the number sub-pulses, from 2 to 32, and the time separation between them, from 1.5 ps to 24 ps, was systematically investigated and compared to the case of unsplit pulses. The spatial periods and depths of the LIPSS produced by different irradiation conditions were derived by scanning electron and atomic force microscopies revealing that, in case of bursts with only two sub-pulses, an increase of the intra-burst delay produces nanoripples with higher spatial separation but shallower depth which is ascribed to a shielding effect. Whereas, increasing the number of sub-pulses a slight increase of the LIPSS spatial period has been observed.