scholarly journals On the Interplay of DLIP and LIPSS Upon Ultra-Short Laser Pulse Irradiation

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1018 ◽  
Author(s):  
Sabri Alamri ◽  
Fotis Fraggelakis ◽  
Tim Kunze ◽  
Benjamin Krupop ◽  
Girolamo Mincuzzi ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Surface Morphology ◽  
Spot Size ◽  
Surface Structures ◽  
Laser Source ◽  
Periodic Patterns ◽  
Simultaneous Generation ◽  
Periodic Surface ◽  
Direct Laser ◽  
Surface Patterns

Controlling laser induced surface morphology is essential for developing specialized functional surfaces. This work presents novel, multi-scale periodic patterns with two-dimensional symmetry generated on stainless steel, polyimide and sapphire. The microstructures were realized by combining Direct Laser Interference Patterning with the generation of Laser Induced Periodic Surface Structures in a one-step process. An industrial, fiber femtosecond laser source emitting at 1030 nm with a pulse duration of 500 fs was utilized for the experiments. In the case of stainless steel, it was possible to create line-like or pillar-like surface patterns by rotating the polarization orientation with respect to the interference pattern. In the case of polyimide and sapphire, the absorption of the laser radiation was promoted by a multiphoton mechanism. In polyimide, grooves and pillars of several microns in depth were produced over an area much larger than the spot size. Finally, for sapphire, the simultaneous generation of interference-like pattern and laser induced periodic surface structures was realized. The results reported here provide valuable data on the feasibility to combine two state-of-the-art techniques with an industrial apparatus, to control the induced surface morphology.

scholarly journals Picosecond Laser Interference Patterning of Periodical Micro-Architectures on Metallic Molds for Hot Embossing

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3409 ◽  
Author(s):  
Yangxi Fu ◽  
Marcos Soldera ◽  
Wei Wang ◽  
Bogdan Voisiat ◽  
Andrés Fabián Lasagni
Keyword(s):  
Picosecond Laser ◽  
Processing Parameters ◽  
Hot Embossing ◽  
Surface Structures ◽  
Laser Source ◽  
Laser Interference ◽  
Periodic Surface ◽  
Direct Laser ◽  
Direct Laser Interference Patterning ◽  
532 Nm

In this work, it is demonstrated that direct laser interference patterning (DLIP) is a method capable of producing microtextured metallic molds for hot embossing processes. Three different metals (Cr, Ni, and Cu), relevant for the mold production used in nanoimprinting systems, are patterned by DLIP using a picosecond laser source emitting at a 532 nm wavelength. The results show that the quality and surface topography of the produced hole-like micropatterns are determined by the laser processing parameters, such as irradiated energy density and the number of pulses. Laser-induced periodic surface structures (LIPSS) are also observed on the treated surfaces, whose shapes, periodicities, and orientations are strongly dependent on the accumulated fluence. Finally, the three structured metals are used as embossing molds to imprint microlenses on polymethyl methacrylate (PMMA) foils using an electrohydraulic press. Topographical profiles demonstrate that the obtained structures are comparable to the masters showing a satisfactory reproduction of the texture. The polymeric microlens arrays that showed the best surface homogeneity and overall quality were those embossed with the Cr molds.

scholarly journals Direct Laser Interference Patterning of Diffraction Gratings in Safrofilcon-A Hydrogel: Fabrication and Hydration Assessment

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 679
Author(s):  
Daniel Sola ◽  
Stephan Milles ◽  
Andrés F. Lasagni
Keyword(s):  
Laser Fluence ◽  
Contact Lenses ◽  
Laser Source ◽  
Spatial Period ◽  
Laser Interference ◽  
Periodic Patterns ◽  
Hydration Properties ◽  
Water Contact ◽  
Direct Laser ◽  
Direct Laser Interference Patterning

Refractive index modification by laser micro-structuration of diffractive optical devices in ophthalmic polymers has recently been applied for refractive correction in the fields of optics and ophthalmology. In this work, Safrofilcon-A hydrogel, used as soft contact lenses, was processed by direct laser interference patterning (DLIP) to fabricate linear periodic patterns on the surface of the samples. Periodic modulation of the surface was attained under two-beam interference by using a Q-switched laser source with emission at 263 nm and 4 ns pulse duration. Features of processed areas were studied as a function of both the interference spatial period and the laser fluence. Optical confocal microscopy used to evaluate the topography of the processed samples showed that both structured height and surface roughness increased with laser fluence. Static water contact angle (WCA) measurements were carried out with deionized water droplets on the structured areas to evaluate the hydration properties of DLIP structures. It was observed that the laser structured areas induced a delay in the hydration process. Finally, microstructural changes induced in the structured areas were assessed by confocal micro-Raman spectroscopy showing that at low laser fluences the polymer structure remained almost unaltered. In addition, Raman spectra of hydrated samples recovered the original shape of areas structured at low laser fluence.

scholarly journals Tunable laser induced periodic surface structures in Ge2Sb2Te5 thin films

2021 ◽  
Vol 2086 (1) ◽  
pp. 012170
Author(s):  
Irina G Bessonova ◽  
Pavel I Trofimov ◽  
Petr I Lazarenko ◽  
Demid A Kirilenko ◽  
Nikolay A Bert ◽  
...  
Keyword(s):  
Thin Films ◽  
Phase Change ◽  
Low Cost ◽  
Beam Steering ◽  
Tunable Laser ◽  
Surface Structures ◽  
Periodic Surface ◽  
Light Localization ◽  
Rapid Fabrication ◽  
Direct Laser

Abstract Planar photonic structures, such as gratings and metasurfaces, are routinely used for beam steering, waveguide coupling, and light localization. However, conventional fabrication techniques that involve lithography are demanding in terms of time and cost. Much cheaper and simpler methods for surface patterning and formation of periodic surface structures are enabled by direct laser processing. Here, we demonstrate low-cost rapid fabrication of high-quality phase gratings based on the formation of laser induced periodic surface structures (LIPSS, or ripples) in Ge2Sb2Te5 (GST) thin films. Due to unique phase change properties of GST, the structures demonstrate strong modulation of refractive index with period controlled by the wavelength of laser irradiation. We study the formation of phase change LIPSS in a broad range of excitation wavelengths and observe transition between regimes with different orientations of generated ripples with respect to laser polarization.

Laser interference ablation by ultrashort UV laser pulses via diffractive beam management

2020 ◽  
Vol 9 (1-2) ◽  
pp. 41-52 ◽  
Author(s):  
Jan-Hendrik Klein-Wiele ◽  
Andreas Blumenstein ◽  
Peter Simon ◽  
Jürgen Ihlemann
Keyword(s):  
Laser Pulses ◽  
Diffractive Optical Elements ◽  
Uv Laser ◽  
Laser Interference ◽  
Periodic Patterns ◽  
Optical Elements ◽  
Periodic Surface ◽  
Coherent Beams ◽  
Surface Patterns ◽  
Computer Generated Holograms

AbstractThe fabrication of periodic surface patterns on various materials by ultrashort ultraviolet (UV) laser pulses is reviewed. Laser interference ablation using two or more coherent beams leads to deterministic, strictly periodic patterns. The generation of the interfering beams is accomplished by diffractive optical elements like gratings, grating systems or computer-generated holograms. The recombination of the diffracted beams is performed by optical imaging or diffractive beam management. Ultrashort UV pulses are especially suited for generating micron- to submicron-sized deterministic periodic patterns on metals and semiconductors.

scholarly journals Formation of Highly Ordered Platinum Nanowire Arrays on Silicon via Laser-Induced Self-Organization

Nanomaterials ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 1031
Author(s):  
Michael Dasbach ◽  
Hendrik M. Reinhardt ◽  
Norbert A. Hampp
Keyword(s):  
Thin Films ◽  
Nanowire Arrays ◽  
Surface Structures ◽  
Self Organization ◽  
Periodic Patterns ◽  
Periodic Surface ◽  
Platinum Nanowires ◽  
Nanosecond Pulsed Laser ◽  
Sputter Deposited ◽  
20 Nm

Laser-induced periodic surface structures (LIPSS) provide an elegant solution for the generation of highly ordered periodic patterns on the surface of solids. In this study, LIPSS are utilized for the formation of periodic platinum nanowire arrays. In a process based on laser-stimulated self-organization, platinum thin films, sputter-deposited onto silicon, are transformed into nanowire arrays with an average periodicity of 538 nm. The width of the platinum nanowires is adjustable in a range from 20 nm to 250 nm by simply adjusting the thickness of the initial platinum thin films in a range from 0.3 nm to 4.3 nm. With increasing width, platinum nanowires show a rising tendency to sink into the surface of the silicon wafer, thus indicating alloying between platinum and silicon upon LIPSS-formation by a nanosecond-pulsed laser. The Pt/silicon wires may be etched away, leaving a complementary nanostructure in the silicon surface.

scholarly journals Subwavelength Direct Laser Nanopatterning Via Microparticle Arrays for Functionalizing Metallic Surfaces

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Jean-Michel Romano ◽  
Rajib Ahmed ◽  
Antonio Garcia-Giron ◽  
Pavel Penchev ◽  
Haider Butt ◽  
...  
Keyword(s):  
Focal Length ◽  
Near Field ◽  
Cost Effective ◽  
Spot Size ◽  
Metallic Surface ◽  
Metallic Surfaces ◽  
Large Area ◽  
Transitional State ◽  
Direct Laser ◽  
Surface Patterns

Functionalized metallic nanofeatures can be selectively fabricated via ultrashort laser processing; however, the cost-effective large-area texturing, intrinsically constrained by the diffraction limit of light, remains a challenging issue. A high-intensity near-field phenomenon that takes place when irradiating microsized spheres, referred to as photonic nanojet (PN), was investigated in the transitional state between geometrical optics and dipole regime to fabricate functionalized metallic subwavelength features. Finite element simulations were performed to predict the PN focal length and beam spot size, and nanofeature formation. A systematic approach was employed to functionalize metallic surface by varying the pulse energy, focal offset, and number of pulses to fabricate controlled array of nanoholes and to study the generation of triangular and rhombic laser-induced periodic surface structures (LIPSS). Finally, large-area texturing was investigated to minimize the dry laser cleaning (DLC) effect and improve homogeneity of PN-assisted texturing. Tailored dimensions and densities of achievable surface patterns could provide hexagonal light scattering and selective optical reflectance for a specific light wavelength. Surfaces exhibited controlled wetting properties with either hydrophilicity or hydrophobicity. No correlation was found between wetting and microbacterial colonization properties of textured metallic surfaces after 4 h incubation of Escherichia coli. However, an unexpected bacterial repellency was observed.

In vitro study on the response of RAW264.7 and MS-5 fibroblast cells on laser-induced periodic surface structures for stainless steel alloys

RSC Advances ◽  
2015 ◽  
Vol 5 (53) ◽  
pp. 42548-42558 ◽  
Author(s):  
Clare McDaniel ◽  
Olga Gladkovskaya ◽  
Aiden Flanagan ◽  
Yury Rochev ◽  
Gerard M. O'Connor
Keyword(s):  
Stainless Steel ◽  
Surface Topography ◽  
Cell Attachment ◽  
In Vitro Study ◽  
Surface Structures ◽  
Fibroblast Cells ◽  
Steel Alloys ◽  
Periodic Surface ◽  
Stent Surface

Cell attachment and growth can be controlled by stent surface topography. In some cases fibroblast cells attach while monocytes failed on the structured surface of Pt:SS and 316LSS stents.

Laser Nanopatterning for Wettability Applications

2017 ◽  
Vol 5 (2) ◽  
Author(s):  
Leonardo Orazi ◽  
Iaroslav Gnilitskyi ◽  
Ana Paula Serro
Keyword(s):  
Stainless Steel ◽  
Femtosecond Laser ◽  
High Speed ◽  
Surface Structures ◽  
Periodic Surface ◽  
Hydrophobic Behavior

We report on periodic, homogeneous nanoripples fabricated on stainless steel (SS), copper (Cu), and aluminum (Al) substrates using an ytterbium pulsed femtosecond laser. These structures called laser induced periodic surface structures (LIPSS) are processed at a relatively high-speed and over large areas. This paper investigates the effect of LIPSS on a wettability behavior of SS, Cu, and Al surfaces. It is shown that nanoripples significantly influenced the wettability character of these metals turning them from hydrophilic to hydrophobic behavior.

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