scholarly journals The Role of the Laser-Induced Oxide Layer in the Formation of Laser-Induced Periodic Surface Structures

Nanomaterials ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 147 ◽  
Author(s):  
Camilo Florian ◽  
Jean-Luc Déziel ◽  
Sabrina V. Kirner ◽  
Jan Siegel ◽  
Jörn Bonse
Keyword(s):  
Spatial Frequency ◽  
Oxide Layer ◽  
Structural Characteristics ◽  
High Spatial Frequency ◽  
Laser Pulses ◽  
Surface Structures ◽  
Layered System ◽  
Periodic Surface ◽  
New Type ◽  
The Impact

Laser-induced periodic surface structures (LIPSS) are often present when processing solid targets with linearly polarized ultrashort laser pulses. The different irradiation parameters to produce them on metals, semiconductors and dielectrics have been studied extensively, identifying suitable regimes to tailor its properties for applications in the fields of optics, medicine, fluidics and tribology, to name a few. One important parameter widely present when exposing the samples to the high intensities provided by these laser pulses in air environment, that generally is not considered, is the formation of a superficial laser-induced oxide layer. In this paper, we fabricate LIPSS on a layer of the oxidation prone hard-coating material chromium nitride in order to investigate the impact of the laser-induced oxide layer on its formation. A variety of complementary surface analytic techniques were employed, revealing morphological, chemical and structural characteristics of well-known high-spatial frequency LIPSS (HSFL) together with a new type of low-spatial frequency LIPSS (LSFL) with an anomalous orientation parallel to the laser polarization. Based on this input, we performed finite-difference time-domain calculations considering a layered system resembling the geometry of the HSFL along with the presence of a laser-induced oxide layer. The simulations support a scenario that the new type of LSFL is formed at the interface between the laser-induced oxide layer and the non-altered material underneath. These findings suggest that LSFL structures parallel to the polarization can be easily induced in materials that are prone to oxidation.

scholarly journals Influence of Bulk Temperature on Laser-Induced Periodic Surface Structures on Polycarbonate

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1947 ◽  
Author(s):  
Marek Mezera ◽  
Jörn Bonse ◽  
Gert-willem R. B. E. Römer
Keyword(s):  
Spatial Frequency ◽  
Laser Energy ◽  
High Spatial Frequency ◽  
Laser Pulses ◽  
Processing Parameters ◽  
Surface Structures ◽  
Bulk Temperature ◽  
Periodic Surface ◽  
Peak Fluence ◽  
First Time

In this paper, the influence of the bulk temperature (BT) of Polycarbonate (PC) on the occurrence and growth of Laser-induced Periodic Surface Structures (LIPSS) is studied. Ultrashort UV laser pulses with various laser peak fluence levels F 0 and various numbers of overscans ( N OS ) were applied on the surface of pre-heated Polycarbonate at different bulk temperatures. Increased BT leads to a stronger absorption of laser energy by the Polycarbonate. For N OS < 1000 High Spatial Frequency LIPSS (HSFL), Low Spatial Frequency LIPSS perpendicular (LSFL-I) and parallel (LSFL-II) to the laser polarization were only observed on the rim of the ablated tracks on the surface but not in the center of the tracks. For N OS ≥ 1000 , it was found that when pre-heating the polymer to a BT close its glass transition temperature ( T g ), the laser fluence to achieve similar LIPSS as when processed at room temperature decreases by a factor of two. LSFL types I and II were obtained on PC at a BT close to T g and their periods and amplitudes were similar to typical values found in the literature. To the best of the author’s knowledge, it is the first time both LSFL types developed simultaneously and consistently on the same sample under equal laser processing parameters. The evolution of LIPSS from HSFL, over LSFL-II to LSFL I, is described, depending on laser peak fluence levels, number of pulses processing the spot and bulk temperature.

scholarly journals Large-area fabrication of low- and high-spatial-frequency laser-induced periodic surface structures on carbon fibers

Carbon ◽  
2018 ◽  
Vol 133 ◽  
pp. 176-185 ◽  
Author(s):  
Clemens Kunz ◽  
Tobias N. Büttner ◽  
Björn Naumann ◽  
Anne V. Boehm ◽  
Enrico Gnecco ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Carbon Fibers ◽  
High Spatial Frequency ◽  
Surface Structures ◽  
Large Area ◽  
Periodic Surface ◽  
Frequency Laser

scholarly journals Impact of Pre-Patterned Structures on Features of Laser-Induced Periodic Surface Structures

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7330
Author(s):  
Stella Maragkaki ◽  
Panagiotis C. Lingos ◽  
George D. Tsibidis ◽  
George Deligeorgis ◽  
Emmanuel Stratakis
Keyword(s):  
Laser Pulses ◽  
Laser Wavelength ◽  
Femtosecond Laser Pulses ◽  
Surface Structures ◽  
Periodic Pattern ◽  
Patterned Surfaces ◽  
Periodic Surface ◽  
Multi Scale ◽  
Patterned Structures ◽  
The Impact

The efficiency of light coupling to surface plasmon polariton (SPP) represents a very important issue in plasmonics and laser fabrication of topographies in various solids. To illustrate the role of pre-patterned surfaces and impact of laser polarisation in the excitation of electromagnetic modes and periodic pattern formation, Nickel surfaces are irradiated with femtosecond laser pulses of polarisation perpendicular or parallel to the orientation of the pre-pattern ridges. Experimental results indicate that for polarisation parallel to the ridges, laser induced periodic surface structures (LIPSS) are formed perpendicularly to the pre-pattern with a frequency that is independent of the distance between the ridges and periodicities close to the wavelength of the excited SPP. By contrast, for polarisation perpendicular to the pre-pattern, the periodicities of the LIPSS are closely correlated to the distance between the ridges for pre-pattern distance larger than the laser wavelength. The experimental observations are interpreted through a multi-scale physical model in which the impact of the interference of the electromagnetic modes is revealed.

scholarly journals Fabricating Laser-Induced Periodic Surface Structures on Medical Grade Cobalt–Chrome–Molybdenum: Tribological, Wetting and Leaching Properties

Lubricants ◽  
2019 ◽  
Vol 7 (8) ◽  
pp. 70 ◽  
Author(s):  
Sanne van der Poel ◽  
Marek Mezera ◽  
Gert-willem Römer ◽  
Erik de Vries ◽  
Dave Matthews
Keyword(s):  
Spatial Frequency ◽  
High Spatial Frequency ◽  
Hierarchical Structures ◽  
Surface Structures ◽  
Hazardous Substances ◽  
Laser Source ◽  
Hip Implants ◽  
Periodic Surface ◽  
Cobalt Chrome ◽  
Counter Surface

Hip-implants structured with anti-bacterial textures should show a low-friction coefficient and should not leach hazardous substances into the human body. The surface of a typical material used for hip-implants, namely Cobalt–Chrome–Molybdenum (CoCrMo) was textured with different types of laser-induced periodic surface structures (LIPSS)—i.e., low spatial frequency LIPSS (LSFL), hierarchical structures consisting of grooves superimposed with high spatial frequency LIPSS (HSFL) and Triangular shaped Nanopillars (TNP)—using a picosecond pulsed laser source. The effect of LIPSS on the wettability, friction, as well as wear of the structures, when slid against a polyethylene (PE) counter surface and biocompatibility was analyzed. Surfaces covered with LSFL show superhydrophobicity and grooves with superimposed HSFL, as well as TNP, show hydrophobic behavior. The coefficient of friction (CoF) of LIPSS against a polyethylene (PE) counter surface was found to be higher (ranging from 0.40 to 0.66) than the CoF of (polished) CoCrMo, which was found to equal 0.22. It was found that the samples release cobalt within biocompatible limits. Compared to polished reference surfaces, LIPSS cause higher friction of CoCrMo against PE contact. However, the wear of the PE counter surface only increased significantly for the LSFL textures. For these reasons, it is concluded that LIPSS are not suitable for a heavily loaded metal-on-plastic bearing contact.

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