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Double- and Multi-Femtosecond Pulses Produced by Birefringent Crystals for the Generation of 2D Laser-Induced Structures on a Stainless Steel Surface
摘要： Laser-induced textures have been proven to be excellent solutions for modifying wetting, friction, biocompatibility, and optical properties of solids. The possibility to generate 2D-submicron morphologies by laser processing has been demonstrated recently. Employing double-pulse irradiation, it is possible to control the induced structures and to fabricate novel and more complex 2D-textures. Nevertheless, double-pulse irradiation often implies the use of sophisticated setups for modifying the pulse polarization and temporal profile. Here, we show the generation of homogeneous 2D-LIPSS (laser-induced periodic surface structures) over large areas utilizing a simple array of birefringent crystals. Linearly and circularly polarized pulses were applied, and the optimum process window was defined for both. The results are compared to previous studies, which include a delay line, and the reproducibility between the two techniques is validated. As a result of a systematic study of the process parameters, the obtained morphology was found to depend both on the interplay between fluence and inter-pulse delay, as well as on the number of incident pulses. The obtained structures were characterized via SEM (scanning electron microscopy) and atomic force microscopy. We believe that our results represent a novel approach to surface structuring, primed for introduction in an industrial environment.
关键词： metal surface texturing,2D-LIPSS,femtosecond,micro/nanostructuring,birefringent crystals,double pulses
更新于2025-11-14 14:32:36
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Nanostructured Transparent Conductive Electrodes for Applications in Harsh Environments Fabricated via Nanosecond Laser‐Induced Periodic Surface Structures (LIPSS) in Indium–Tin Oxide Films on Glass
摘要： A self-organization phenomenon named laser-induced periodic surface structures (LIPSS) is utilized for pattern formation in indium–tin oxide (ITO) transparent conductive films coated on borosilicate glass. Stripe patterns with periodicities down to 175 nm are created by scanning the focused beam (30 μm spot diameter 1 e?2) of a nanosecond pulsed laser operating at 532 nm wavelength over ITO films. Highly ordered ITO-LIPSS are generated at a pulse duration of 6 ns, pulse frequencies between 100 and 200 kHz, pulse energies around 20 μJ, and laser spot scan speeds in the range of 50–80 mm s?1. Resulting nanopatterns are electrically conductive and feature improved optical transparency as well as stability against strong acids such as hydrochloric acid, sulfuric acid, and even aqua regia. The formation of mixed phases between ITO and silicon is considered to be the origin for the chemical robustness of laser patterned transparent conductive electrodes.
关键词： laser-induced periodic surface structures (LIPSS),laser patterning,self-organization,indium–tin oxide (ITO),transparent conductive films (TCF)
更新于2025-10-22 19:40:53
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Femtosecond laser irradiation of titanium oxide thin films: accumulation effect under IR beam
摘要： This paper discusses the mechanisms of laser-induced periodic surface structures (LIPSS) formation using a high repetition rate femtosecond laser beam irradiation of magnetron-sputtered titanium oxide thin films (TiO1.8) grown onto SiO2/Si substrates. An Yb:YKW 500 fs linearly polarized laser emitting at a wavelength, λ, of 1030 nm, was used to irradiate the films (300 nm thickness) at a repetition rate of 100 kHz under both static and dynamic (scanning) conditions. Under static beam conditions, an incubation behavior related to materials in thin film form was established with a damage threshold of 72 mJ/cm2. Close to this fluence value and increasing the number of laser shots from 1 to 1000, micro-cracking occurred and propagated inside the beam waist diameter zone estimated close to 60 μm. In addition, using a higher fluence value of 280 mJ/cm2, i.e., well above the damage threshold, a melting occurred in an intermediate zone within the irradiated area, with a surprising ‘cure effect’ that contributes to the micro-cracks stabilization. Simultaneously, at the center of the Gaussian laser beam spot, the entire film ablation was observed. Furthermore, irradiation under dynamic mode with a scanning speed of 4 mm/s and a repetition rate of 100 kHz were achieved for the large-scale processing of the TiO1.8 films up to surface area of 25 × 25 mm2. For these irradiation conditions case that correspond to a fluence of 110 mJ/cm2 and a cumulative number of shots of 3000, 2D-LIPSS nano-cracks (200 nm length and λ/8 to λ/9 period) are obtained over the whole irradiated surface, a phenomenon that is mainly attributed to a thermo-mechanical ablation mechanism.
关键词： Femtosecond laser beam,Titanium oxide film,Micro/nano-cracks,High repetition rate,Incubation,LIPSS
更新于2025-09-23 15:21:01
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Micro and Nanoscale Laser Processing of Hard Brittle Materials || Surface nanostructuring of hard brittle materials
摘要： In the recent developments of laser processing technology, there has been exponentially growing interest in surface structuring. A wide variety of shapes and sizes can be achieved for the structures depending on the laser parameters applied. In this chapter, we will be focusing on nanoscale surface structuring. Laser surface nanostructuring is such an attractive process, from a technological point of view, as it is so simple. Nanostructures can be generated on a large surface area using a single-step process; this is impossible on hard brittle materials by any other methods. However, as is the case with many simple technologies, the fundamental science behind it is highly complex. Surface structure generation is attributed to a complex combination of inter- and intrapulse physical processes. This chapter will attempt to clarify the scientific processes of the nanostructure formation mechanism, to describe recent trends in nanostructuring technology, and to present innovative applications of nanostructured surfaces with particular focus on the surface nanostructuring of silicon and zirconia.
关键词： zirconia,surface nanostructuring,LIPSS,silicon,laser processing
更新于2025-09-23 15:21:01
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Surface functionalization by laser-induced periodic surface structures
摘要： In recent years, the improved understanding of the formation of laser-induced periodic surface structures (LIPSS) has led to an emerging variety of applications that modify the optical, mechanical, and chemical properties of many materials. Such structures strongly depend on the laser beam polarization and are formed usually after irradiation with ultrashort linearly polarized laser pulses. The most accepted explanation for the origin of the structures is based on the interference of the incident laser radiation with electromagnetic surface waves that propagate or scatter at the surface of the irradiated materials. This leads to an intensity modulation that is finally responsible for the selective ablation in the form of parallel structures with periods ranging from hundreds of nanometers up to some micrometers. The versatility when forming such structures is based on the high reproducibility with different wavelengths, pulse durations and repetition rate laser sources, customized micro- and nanometric spatial resolutions, and compatibility with industrially relevant processing speeds when combined with fast scanning devices. In this contribution, we review the latest applications in the rapidly emerging field of surface functionalization through LIPSS, including biomimetic functionalities on fluid transport, control of the wetting properties, specific optical responses in technical materials, improvement of tribological performance on metallic surfaces, and bacterial and cell growth for medical devices, among many others.
关键词： applications,laser processing,surface functionalization,laser-induced periodic surface structures (LIPSS)
更新于2025-09-23 15:21:01
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Uniform LIPSS on titanium irradiated by two-color double-pulse beam of femtosecond laser
摘要： The authors have investigated the uniformity of laser-induced periodic surface structures (LIPSSs) generated on titanium surfaces irradiated with a two-color double-pulse cross-polarized beam with a time delay of Δt = 0–200 ps. The double-pulse beam consisted of 800 nm pulses with a duration of 150 fs and 400 nm pulses with a duration of >150 fs. The fundamental-pulse fluence F800 and the second-harmonic pulse fluence F400 were set to be near the corresponding ablation thresholds of F800th = 0.108 J/cm2 and F400th = 0.090 J/cm2, respectively. The authors found that uniform LIPSSs could be produced on titanium surfaces using laser fluences of 1.5F400th + 0.9F800th and a delay of Δt = 0–2 ps. The periodicity and direction of the LIPSSs were characterized by the wavelength and electric field of the fundamental (800 nm) pulse. The results suggest that the longer-wavelength pulse influences surface plasma wave generation and improves uniformity by the second harmonic pulse even though laser plasma is produced on the surface.
关键词： femtosecond laser,double pulse beam,titanium,LIPSS
更新于2025-09-23 15:21:01
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Laser-Induced Periodic Surface Structuring of Poly(trimethylene terephthalate) Films Containing Tungsten Disulfide Nanotubes
摘要： We report the study of the formation of Laser Induced Periodic Surface Structures (LIPSS), with UV femtosecond laser pulses (λ = 265 nm), in free-standing films of both Poly(trimethylene terephthalate) (PTT) and the composite PTT/tungsten disulfide inorganic nanotubes (PTT-WS2). We characterized the range of fluences and number of pulses necessary to induce LIPSS formation and measured the topography of the samples by Atomic Force Microscopy, the change in surface energy and contact angle using the sessile drop technique, and the modification in both Young’s modulus and adhesion force values with Peak Force-Quantitative Nanomechanical Mapping. LIPSS appeared parallel to the laser polarization with a period close to its wavelength in a narrow fluence and number of pulses regime, with PTT-WS2 needing slightly larger fluence than raw PTT due to its higher crystallinity and heat diffusion. Little change was found in the total surface energy of the samples, but there was a radical increase in the negative polar component (???). Besides, we measured small variations in the samples Young’s modulus after LIPSS formation whereas adhesion is reduced by a factor of four. This reduction, as well as the increase in ???, is a result of the modification of the surface chemistry, in particular a slight oxidation, during irradiation.
关键词： nanocomposites,ultrashort pulses,laser material processing,nanostructures,LIPSS
更新于2025-09-23 15:21:01
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Chemical effects during the formation of various types of femtosecond laser-generated surface structures on titanium alloy
摘要： In this contribution, chemical, structural, and mechanical alterations in various types of femtosecond laser-generated surface structures, i.e., laser-induced periodic surface structures (LIPSS, ripples), Grooves, and Spikes on titanium alloy, are characterized by various surface analytical techniques, including X-ray diffraction and glow-discharge optical emission spectroscopy. The formation of oxide layers of the different laser-based structures inherently influences the friction and wear performance as demonstrated in oil-lubricated reciprocating sliding tribological tests (RSTTs) along with subsequent elemental mapping by energy-dispersive X-ray analysis. It is revealed that the fs-laser scan processing (790 nm, 30 fs, 1 kHz) of near-wavelength-sized LIPSS leads to the formation of a graded oxide layer extending a few hundreds of nanometers into depth, consisting mainly of amorphous oxides. Other superficial fs-laser-generated structures such as periodic Grooves and irregular Spikes produced at higher fluences and effective number of pulses per unit area present even thicker graded oxide layers that are also suitable for friction reduction and wear resistance. Ultimately, these femtosecond laser-induced nanostructured surface layers efficiently prevent a direct metal-to-metal contact in the RSTT and may act as an anchor layer for specific wear-reducing additives contained in the used engine oil.
关键词： Tribology,Femtosecond laser processing,GD-OES,Surface chemistry,XRD,LIPSS,Laser-induced periodic surface structures,Laser-induced oxide layer
更新于2025-09-23 15:19:57
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Femtosecond laser fabrication of LIPSS-based waveplates on metallic surfaces
摘要： A fast and reliable method for the fabrication of polarization modifying devices using femtosecond laser is reported. A setup based on line focusing is used for the generation of LIPSS on stainless steel, processing at different speeds between 0.8 and 2.4 mm/s with constant energy per pulse of 1.4 mJ. SEM and AFM characterizations of the LIPSS show a progressive increase in period as the processing speed increases, while height remains approximately constant in the studied range. Optical characterization of the devices shows an induced change in the polarization of the reflected beam that varies with the processing speed, which allows a controlled fabrication of these devices.
关键词： polarization,waveplate,femtosecond,laser,LIPSS,nanostructure
更新于2025-09-23 15:19:57
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Editorial: Special Issue a??Laser-Induced Periodic Surface Nano- and Microstructures for Tribological Applicationsa??
摘要： Laser material processing is an innovative technology that generates surface functionalities on the basis of optical, mechanical, or chemical properties. In the form of laser surface texturing (LST), it has attracted a remarkable amount of research to tailor surface properties towards various tribological applications. Of this single-step, laser-based technology, the main advantages are the contactless machining, featuring a high flexibility, efficiency, and speed, along with the excellent quality of the processed products. LST can be applied precisely, localized to sub-micrometric areas, but, via laser beam scanning, it is also feasible for structuring large surface areas the size of square-meters.
关键词： microstructure,wear,laser-induced periodic surface structures (LIPSS),lubricant,applications,friction,tribology,nanostructure
更新于2025-09-23 15:19:57