TY - JOUR A1 - Grehn, M. A1 - Seuthe, T. A1 - Reinhardt, F. A1 - Höfner, M. A1 - Griga, N. A1 - Eberstein, M. A1 - Bonse, Jörn T1 - Debris of potassium-magnesium silicate glass generated by femtosecond laser-induced ablation in air: An analysis by near edge X-ray absorption spectroscopy, micro Raman and energy dispersive X-ray spectroscopy N2 - The redeposited material (debris) resulting from ablation of a potassium–magnesium silicate glass upon scanning femtosecond laser pulse irradiation (130 fs, 800 nm) in air environment is investigated by means of three complementary surface analytical methods. Changes in the electronic band structure of the glass constituent Magnesium (Mg) were identified by X-ray Absorption Near Edge Structure spectroscopy (XANES) using synchrotron radiation. An up-shift of ≈0.8 eV of a specific Magnesium Κ-edge absorption peak in the spectrum of the redeposited material along with a significant change in its leading edge position was detected. In contrast, the surface left after laser ablation exhibits a downshift of the peak position by ≈0.9 eV. Both observations may be related to a change of the Mg coordinative state of the laser modified/redeposited glass material. The presence of carbon in the debris is revealed by micro Raman spectroscopy (µ-RS) and was confirmed by energy dispersive X-ray spectroscopy (EDX). These observations are attributed to structural changes and chemical reactions taking place during the ablation process. KW - Femtosecond laser ablation KW - Potassium-magnesium silicate glass KW - Debris KW - XANES KW - EDX KW - Raman spectroscopy PY - 2014 DO - https://doi.org/10.1016/j.apsusc.2013.10.028 SN - 0169-4332 SN - 1873-5584 VL - 302 SP - 286 EP - 290 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-30454 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Mimicking lizard-like surface structures upon ultrashort laser pulse irradiation of inorganic materials N2 - The wetting behavior of material surfaces can be controlled by surface structures. We functionalized inorganic material surfaces, such as steel, titanium alloy and silicon, to modify the wetting behavior using ultrashort laser pulses (fs- to ps-range). The laser processing was performed by scanning the laser beam across the surface of initially polished flat sample material. A combined experimental and theoretical study of the laser processing parameters (peak fluence, scan velocity, line overlap) allowed the identification of different regimes associated with characteristic surface morphologies (laser-induced periodic surface structures, grooves, micro cones, dimples, etc.). Analyses of the surface using optical as well as scanning electron microscopy allowed the identification of morphologies providing the optimum similarity to the natural skin of lizards. For mimicking skin structures of moisture-harvesting lizards towards an optimization of the surface wetting behavior, additionally, a two-step laser processing strategy was established for realizing hierarchical micro- and nanostructures. In this approach, a laser-generated regular array of small dimples was superimposed (step 2) to the micron-scaled capillaries processed before (step 1). Optical focus variation imaging measurements finally revealed the three dimensional topography of the laser processed surfaces derived from lizard skin structures. The functionality of these surfaces was analyzed in view of wetting properties. T2 - E-MRS 2016 Spring Meeting, Symposium C: "Laser-material interactions for tailoring future applications" CY - Lille, France DA - 02.05.2016 KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser ablation KW - Steel KW - Lizard KW - Wetting PY - 2016 AN - OPUS4-36047 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Tribological properties of femtosecond laserinduced periodic surface structures on metals N2 - Laser-induced periodic surface structures (LIPSS, ripples) were generated on steel and titanium surfaces upon irradiation with multiple linear polarized femtosecond laser pulses (pulse duration 30 fs, central wavelength 790 nm). The experimental conditions (laser fluence, spatial spot overlap) were optimized in a sample-scanning geometry for the processing of large surface areas covered homogeneously by the nanostructures. The irradiated surface regions were subjected to optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM) revealing sub-wavelength spatial periods. The nanostructured surfaces were tribologically tested under reciprocal sliding conditions against a sphere of hardened 100Cr6 steel at 1 Hz using paraffin oil and engine oil as lubricants. After 1000 sliding cycles at a load of 1.0 N, the corresponding wear tracks were characterized by OM and SEM. For specific conditions the laser-generated nanostructures endured the tribological treatment. Simultaneously, a significant reduction of the friction coefficient was observed in the laser-irradiated (LIPSS-covered) areas when compared to the non-irradiated surface, indicating the potential benefit of laser surface structuring for tribological applications. T2 - SPIE Photonics West Conference, Symposium "Laser Applications in Microelectronic and Optoelectronic Manufacturing" (LAMOM) XXI CY - San Francisco, CA, USA DA - 13.02.2016 KW - Femtosecond laser ablation KW - Laser-induced periodic surface structures (LIPSS) KW - Tribology KW - Friction KW - Wear PY - 2016 AN - OPUS4-36041 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Höhm, S. A1 - Koter, Robert A1 - Hartelt, Manfred A1 - Spaltmann, Dirk A1 - Pentzien, Simone A1 - Rosenfeld, A. A1 - Krüger, Jörg T1 - Tribological performance of sub-100-nm femtosecond laser-induced periodic surface structures on titanium N2 - Sub-100-nm laser-induced periodic surface structures (LIPSS) were processed on bulk titanium (Ti) surfaces by femtosecond laser pulse irradiation in air (30 fs pulse duration, 790 nm wavelength). The laser peak fluence, the spatial spot overlap, and the number of overscans were optimized in a sample-scanning geometry in order to obtain large surface areas (5 mm × 5 mm) covered homogeneously by the LIPSS. The laser-processed regions were characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). The friction coefficient of the nanostructured surfaces was tested during 1000 cycles under reciprocal sliding conditions (1 Hz, 1.0 N normal load) against a 10-mm diameter ball of hardened 100Cr6 steel, both in paraffin oil and in engine oil used as lubricants. Subsequently, the corresponding wear tracks were qualified by OM, SEM, and energy dispersive X-ray analyses (EDX). The results of the tribological tests are discussed and compared to that obtained for near wavelength-sized fs-LIPSS, processed under somewhat different irradiation conditions. Some constraints for a beneficial effect of LIPSS on the tribological performance are provided. KW - Femtosecond laser ablation KW - Laser-induced periodic surface structures, LIPSS KW - Friction KW - Wear KW - Nanostructures KW - Surface functionalization PY - 2016 UR - http://www.sciencedirect.com/science/article/pii/S0169433215026987 DO - https://doi.org/10.1016/j.apsusc.2015.11.019 SN - 0169-4332 SN - 1873-5584 VL - 374 SP - 190 EP - 196 PB - Elsevier B.V. CY - Amsterdam, Netherlands AN - OPUS4-35937 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Höhm, S. A1 - Herzlieb, M. A1 - Rosenfeld, A. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Dynamics of the formation of laser-induced periodic surface structures (LIPSS) upon femtosecond two-color double-pulse irradiation of metals, semiconductors, and dielectrics N2 - In order to address the dynamics and physical mechanisms of LIPSS formation for three different classes of materials (metals, semiconductors, and dielectrics), two-color double-fs-pulse experiments were performed on Titanium, Silicon and Fused Silica. For that purpose a Mach–Zehnder interferometer generated polarization controlled (parallel or cross-polarized) double-pulse sequences at 400 nm and 800 nm wavelength, with inter-pulse delays up to a few picoseconds. Multiple of these two-color double-pulse sequences were collinearly focused by a spherical mirror to the sample surfaces. The fluence of each individual pulse (400 nm and 800 nm) was always kept below its respective ablation threshold and only the joint action of both pulses lead to the formation of LIPSS. Their resulting characteristics (periods, areas) were analyzed by scanning electron microscopy. The periods along with the LIPSS orientation allow a clear identification of the pulse which dominates the energy coupling to the material. For strong absorbing materials (Silicon, Titanium), a wavelength-dependent plasmonic mechanism can explain the delay-dependence of the LIPSS. In contrast, for dielectrics (Fused Silica) the first pulse always dominates the energy deposition and LIPSS orientation, supporting a non-plasmonic formation scenario. For all materials, these two-color experiments confirm the importance of the ultrafast energy deposition stage for LIPSS formation. KW - Femtosecond laser ablation KW - Double-pulse experiments KW - Laser-induced periodic surface structures (LIPSS) KW - Mach-Zehnder interferometer KW - Ultrafast optical techniques PY - 2016 UR - http://www.sciencedirect.com/science/article/pii/S0169433215031347 DO - https://doi.org/10.1016/j.apsusc.2015.12.129 SN - 0169-4332 SN - 1873-5584 VL - 374 SP - 331 EP - 338 PB - Elsevier CY - Amsterdam, Netherlands AN - OPUS4-35938 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lone, S. A. A1 - Muck, M. A1 - Fosodeder, P. A1 - Mardare, C.C. A1 - Florian, Camilo A1 - Weth, A. A1 - Krüger, Jörg A1 - Steinwender, C. A1 - Baumgartner, W. A1 - Bonse, Jörn A1 - Heitz, J. A1 - Hassel, A.W. T1 - Impact of Femtosecond Laser Treatment Accompanied with Anodization of Titanium Alloy on Fibroblast Cell Growth N2 - Herein, Ti6Al4V alloy is surface modified by femtosecond laser ablation. The microstructure image obtained by secondary electron microscopy reveals a combination of micrometer spikes or cones superimposed by nanoripples (laser‐induced periodic surface structures). To make the surface hydrophilic, anodization is performed resulting in further smoothness of microstructure and a final thickness of 35 ± 4 nm is estimated for oxide produced after anodization at 10 V (scan rate = 0.1 V s−1) versus standard hydrogen electrode. The obtained electrochemically active surface area (ECSA) is approximately 8 times larger compared with flat mirror polished Ti6Al4V surface. Combined chemical analysis by Pourbaix diagram and X‐ray photoelectron spectroscopy (XPS) analyses reveal that titanium and aluminum are passivating into TiO2 and Al2O3, but the dissolution of aluminum in the form of solvated ion is inevitable. Finally, cell seeding experiments on anodized and laser‐treated titanium alloy samples show that the growth of murine fibroblast cells is significantly suppressed due to unique surface texture of the laser‐treated and anodized titanium alloy sample. KW - Anodization KW - Femtosecond laser ablation KW - Laser-induced periodic surface structures, LIPSS KW - Ti6Al4V alloys KW - X-ray photoelectron spectroscopy PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-510263 DO - https://doi.org/https://doi.org/10.1002/pssa.201900838 SN - 1862-6300 SN - 1862-6319 VL - 217 IS - 13 SP - 1900838-1 EP - 1900838-9 PB - WILEY-VCH Verlag CY - Weinheim, Germany AN - OPUS4-51026 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Florian, Camilo A1 - Deziel, J.-L. A1 - Kirner, Sabrina V. A1 - Siegel, J. A1 - Bonse, Jörn T1 - Femtosecond laser-induced oxidation in the formation of periodic surface structures N2 - Micro- and nanostructuring with laser-induced periodic surface structures (LIPSS) has been demonstrated to be feasible in a wide variety of materials including metals, semiconductors and dielectrics. Suitable processing regimes for flat, curved and complex surfaces have been identified for many materials, allowing the generation of diverse applications in fields such as optics, tribology and medicine, to name a few. A common side effect when producing such structures in air environment is the formation of a thin surface oxide layer in the laser irradiated areas. Previous studies have shown that oxidation plays an important role in the tribological performance for which the structures where created, and very recently it has been shown that the laser-induced oxide graded layers may contribute to the formation of a new type of embedded low-spatial frequency LIPSS (LSFL) with annomalous orientation parallel to the laser polarization, in addition to the appearance of the well-known high-spatial frequency LIPSS (HSFL) at the surface. In this contribution, we explore this effect experimentally for chromium nitride (CrN) irradiated with femtosecond laser pulses and compare the findings to finite-difference time-domain (FDTD) simulations of the intensity distributions at different depth positions. T2 - 2021 Conference on Lasers and Electro-Optics/Europe – European Quantum Electronics Virtual Conferences CY - Munich, Germany DA - 21.06.2021 KW - Femtosecond laser ablation KW - Finite-difference time-domain calculations KW - Laser-induced periodic surface structures (LIPSS) KW - Surface oxidation PY - 2021 SN - 978-1-6654-1876-8 DO - https://doi.org/10.1109/CLEO/Europe-EQEC52157.2021.9542774 VL - 2021 SP - 1 PB - Institute of Electrical and Electronics Engineers (IEEE) CY - Piscataway, NJ, USA AN - OPUS4-53457 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Kirner, Sabrina V. A1 - Epperlein, Nadja A1 - Spaltmann, Dirk A1 - Krüger, Jörg T1 - Surface functionalization by laser-induced periodic surface structures (LIPSS) N2 - In this contribution the mechanisms of formation and current applications of LIPSS are reviewed, including the colorization of technical surfaces, the control of surface wetting properties, the mimicry of the natural texture of animal integuments, the tailoring of surface colonization by bacterial biofilms, and the improvement of the tribological performance of nanostructured metal surfaces. T2 - 10th Stuttgart Laser Technology Forum 2018 CY - Stuttgart, Germany DA - 05.06.2018 KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser ablation KW - Surface functionalization KW - Wetting KW - Tribology KW - Biofilms PY - 2018 SP - 35 AN - OPUS4-45128 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Surface functionalization by laser-induced periodic surface structures (LIPSS) N2 - Laser-induced periodic surface structures (LIPSS, ripples) are a universal phenomenon that can be observed on almost any material after the irradiation by linearly polarized laser beams, particularly when using ultrashort laser pulses with durations in the femtosecond to picosecond range. During the past few years significantly increasing research activities have been reported in the field of LIPSS, since their generation in a single-step process provides a simple way of nanostructuring and surface functionalization towards the control of optical, mechanical, biological, or chemical surface properties. In this contribution the mechanisms of formation and current applications of LIPSS are reviewed, including the colorization of technical surfaces, the control of surface wetting properties, the mimicry of the natural texture of animal integuments, the tailoring of surface colonization by bacterial biofilms, the advancement of medical pacemakers, and the improvement of the tribological performance of nanostructured metal surfaces. T2 - Stuttgarter Lasertage - SLT 2018 CY - Stuttgart, Germany DA - 05.06.2018 KW - Surface functionalization KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser ablation PY - 2018 AN - OPUS4-45132 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kirner, Sabrina V. A1 - Hermens, U. A1 - Mimidis, A. A1 - Skoulas, E. A1 - Florian, C. A1 - Hischen, F. A1 - Plamadeala, C. A1 - Baumgartner, W. A1 - Winands, K. A1 - Mescheder, H. A1 - Krüger, Jörg A1 - Solis, J. A1 - Siegel, J. A1 - Stratakis, E. A1 - Bonse, Jörn T1 - Mimicking bug-like surface structures and their fluid transport produced by ultrashort laser pulse irradiation of steel N2 - Ultrashort laser pulses with durations in the fs-to-ps range were used for large area surface processing of steel aimed at mimicking the morphology and extraordinary wetting behaviour of bark bugs (Aradidae) found in nature. The processing was performed by scanning the laser beam over the surface of polished flat sample surfaces. A systematic variation of the laser processing parameters (peak fluence and effective number of pulses per spot diameter) allowed the identification of different regimes associated with characteristic surface morphologies (laser-induced periodic surface structures, i.e., LIPSS, grooves, spikes, etc.). Moreover, different laser processing strategies, varying laser wavelength, pulse duration, angle of incidence, irradiation atmosphere, and repetition rates, allowed to achieve a range of morphologies that resemble specific structures found on bark bugs. For identifying the ideal combination of parameters for mimicking bug-like structures, the surfaces were inspected by scanning electron microscopy. In particular, tilted micrometre-sized spikes are the best match for the structure found on bark bugs. Complementary to the morphology study, the wetting behaviour of the surface structures for water and oil was examined in terms of philic/ phobic nature and fluid transport. These results point out a route towards reproducing complex surface structures inspired by nature and their functional response in technologically relevant materials. KW - Biomometics KW - Surface wetting KW - Steel KW - Bug KW - Laser-induced periodic surface structures KW - Fluid transport KW - Femtosecond laser ablation PY - 2017 DO - https://doi.org/10.1007/s00339-017-1317-3 SN - 0947-8396 SN - 1432-0630 VL - 123 IS - 12 SP - 754, 1 EP - 13 AN - OPUS4-42817 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tsibidis, G. D. A1 - Mimidis, A. A1 - Skoulas, E. A1 - Kirner, Sabrina V. A1 - Krüger, Jörg A1 - Bonse, Jörn A1 - Stratakis, E. T1 - Modelling periodic structure formation on 100Cr6 steel after irradiation with femtosecond-pulsed laser beams N2 - We investigate the periodic structure formation upon intense femtosecond pulsed irradiation of chrome steel (100Cr6) for linearly polarised laser beams. The underlying physical mechanism of the laser-induced periodic structures is explored, their spatial frequency is calculated and theoretical results are compared with experimental observations. The proposed theoretical model comprises estimations of electron excitation, heat transfer, relaxation processes, and hydrodynamics-related mass transport. Simulations describe the sequential formation of sub-wavelength ripples and supra-wavelength grooves. In addition, the influence of the laser wavelength on the periodicity of the structures is discussed. The proposed theoretical investigation offers a systematic methodology towards laser processing of steel surfaces with important applications. KW - Laser-induced periodic surface structures KW - Femtosecond laser ablation KW - Steel PY - 2018 UR - https://link.springer.com/article/10.1007/s00339-017-1443-y DO - https://doi.org/10.1007/s00339-017-1443-y SN - 0947-8396 SN - 1432-0630 VL - 124 IS - 1 SP - 27, 1 EP - 13 PB - Springer-Verlag AN - OPUS4-43626 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - Structuring of thin films by ultrashort laser pulses N2 - Modern life and global communication would not be possible without technologically tailored thin films; they are omnipresent in daily life applications. In most cases, the films are deposited entirely at the carrying substrates in a specific processing step of the device or sample. In some cases, however, removal or modification must be performed locally, i.e., site-controlled and material selective through an additional laser processing step. For that ultrashort laser pulses with durations in the femtosecond and picosecond range can provide unique advantages and capabilities in industrially scalable schemes. This article reviews the current state of the research and corresponding industrial transfer related to the structuring of thin films by ultrashort pulsed lasers. It focuses on the pertinent historic developments, reveals the relevant physical and chemical effects, explores the ultimate limits, and discusses selected industrial and scientific applications. KW - Thin films KW - Laser processing KW - Ultrashort lasers KW - Laser damage KW - Femtosecond laser ablation PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-565732 DO - https://doi.org/10.1007/s00339-022-06229-x SN - 0947-8396 SN - 1432-0630 VL - 129 IS - 1 SP - 1 EP - 38 PB - Springer CY - Berlin AN - OPUS4-56573 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Höhm, S. A1 - Herzlieb, M. A1 - Rosenfeld, A. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Laser-induced periodic surface structures on fused silica upon cross-polarized two-color double-fs-pulse irradiation N2 - The dynamics of the formation of laser-induced periodic surface structures (LIPSS) on fused silica upon irradiation with linearly polarized fs-laser pulses (50 fs pulse duration) is studied by cross-polarized two-color double-fs-pulse experiments. In order to analyze the relevance of temporally distributed energy deposition in the early stage of LIPSS formation, a Mach-Zehnder interferometer was used for generating multiple double-pulse sequences at two different wavelengths (400 and 800 nm). The inter-pulse delay between the individual cross-polarized pulses of each sequence was systematically varied in the sub-ps range and the resulting LIPSS morphologies were characterized by scanning electron microscopy. It is found that the polarization of the first laser pulse arriving to the surface determines the orientation and the periodicity of the LIPSS. These two-color experiments further confirm the importance of the ultrafast energy deposition to the silica surface for LIPSS formation, particularly by the first laser pulse of each sequence. The second laser pulse subsequently reinforces the previously seeded spatial LIPSS characteristics (period, orientation). KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser ablation KW - Double-pulse experiments KW - Ultrafast optical techniques KW - Mach-Zehnder interferometer PY - 2015 DO - https://doi.org/10.1016/j.apsusc.2014.09.101 SN - 0169-4332 SN - 1873-5584 VL - 336 SP - 39 EP - 42 PB - North-Holland CY - Amsterdam AN - OPUS4-32860 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Kirner, Sabrina A1 - Koter, Robert A1 - Pentzien, Simone A1 - Spaltmann, Dirk A1 - Krüger, Jörg T1 - Femtosecond laser-induced periodic surface structures on titanium nitride coatings for tribological applications N2 - Titanium nitride (TiN) was coated on different substrate materials, namely pure titanium (Ti), titanium alloy (Ti6Al4V) and steel (100Cr6), generating 2.5 μm thick TiN layers. Using femtosecond laser pulses (30 fs, 790 nm, 1 kHz pulse repetition rate), large surface areas (5 mm × 5 mm) of laser-induced periodic surface structures (LIPSS) with sub-wavelength periods ranging between 470 nm and 600 nm were generated and characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). In tribological tests, coefficients of friction (COF) of the nanostructured surfaces were determined under reciprocating sliding conditions (1 Hz, 1.0 N normal load) against a 10-mm diameter ball of hardened 100Cr6 steel during 1000 cycles using two different lubricants, namely paraffin oil and engine oil. It turned out that the substrate material, the laser fluence and the lubricant are crucial for the tribological performance. However, friction and wear could not be significantly reduced by LIPSS on TiN layers in comparison to unstructured TiN surfaces. Finally, the resulting wear tracks on the nanostructured surfaces were investigated with respect to their morphology (OM, SEM), depth (WLIM) and chemical composition by energy dispersive X-ray spectroscopy (EDX) and, on one hand, compared with each other, on the other hand, with non-structured TiN surfaces. KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser ablation KW - Titanium nitride films KW - Friction KW - Wear PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S0169433216322486 DO - https://doi.org/10.1016/j.apsusc.2016.10.132 SN - 0169-4332 SN - 1873-5584 VL - 418 IS - Part B SP - 572 EP - 579 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-40507 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hermens, U. A1 - Kirner, Sabrina A1 - Emonts, C. A1 - Comanns, P. A1 - Skoulas, E. A1 - Mimidis, A. A1 - Mescheder, H. A1 - Winands, K. A1 - Krüger, Jörg A1 - Stratakis, E. A1 - Bonse, Jörn T1 - Mimicking lizard-like surface structures upon ultrashort laser pulse irradiation of inorganic materials N2 - Inorganic materials, such as steel, were functionalized by ultrashort laser pulse irradiation (fs- to ps-range) to modify the surface’s wetting behavior. The laser processing was performed by scanning the laser beam across the surface of initially polished flat sample material. A systematic experimental study of the laser processing parameters (peak fluence, scan velocity, line overlap) allowed the identification of different regimes associated with characteristic surface morphologies (laser-induced periodic surface structures, grooves, spikes, etc.). Analyses of the surface using optical as well as scanning electron microscopy revealed morphologies providing the optimum similarity to the natural skin of lizards. For mimicking skin structures of moisture-harvesting lizards towards an optimization of the surface wetting behavior, additionally a two-step laser processing strategy was established for realizing hierarchical microstructures. In this approach, micrometer-scaled capillaries (step 1) were superimposed by a laser-generated regular array of small dimples (step 2). Optical focus variation imaging measurements finally disclosed the three dimensional topography of the laser processed surfaces derived from lizard skin structures. The functionality of these surfaces was analyzed in view of wetting properties. KW - Femtosecond laser ablation KW - Laser-induced periodic surface structures KW - Lizard KW - Surface wetting KW - Fluid transport KW - Steel PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S0169433216328306 DO - https://doi.org/10.1016/j.apsusc.2016.12.112 SN - 0169-4332 SN - 1873-5584 VL - 418 IS - Part B SP - 499 EP - 507 PB - Elsevier, North-Holland CY - Amsterdam AN - OPUS4-40509 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn A1 - Höhm, S. A1 - Kirner, Sabrina A1 - Rosenfeld, A. A1 - Krüger, Jörg T1 - Laser-induced periodic surface structures (LIPSS) - A scientific evergreen N2 - The current state in the field of laser-induced periodic surface structures (LIPSS, ripples) is reviewed. Their formation mechanisms are analyzed in ultrafast experiments (time-resolved diffraction and polarization controlled double-pulse experiments) and technological applications are demonstrated. T2 - Conference on Lasers and Electro-Optics (CLEO) - Science and Innovations 2016 CY - San Jose, CA, USA DA - 05.06.2016 KW - Laser materials processing KW - Optics at surfaces KW - Ultrafast phenomena KW - Laser-induced periodic surface strcutures (LIPSS) KW - Femtosecond laser ablation PY - 2016 SN - 978-1-943580-11-8 DO - https://doi.org/10.1364/CLEO_SI.2016.STh1Q.3 SP - STh1Q.3, 1 EP - 2 PB - Optical Society of America AN - OPUS4-37072 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sokolowski-Tinten, K. A1 - Barty, A. A1 - Boutet, S. A1 - Shymanovich, U. A1 - Bogan, M. A1 - Marchesini, S. A1 - Hau-Riege, S. A1 - Stojanovic, N. A1 - Bonse, Jörn A1 - Tobey, R. A1 - Ehrke, H. A1 - Cavalleri, A. A1 - Duesterer, S. A1 - Frank, M. A1 - Bajt, S. A1 - Schulz, J. A1 - Seibert, M. A1 - Hajdu, J. A1 - Treusch, R. A1 - Chapman, H. T1 - Short-pulse laser induced transient structure formation and ablation studied with time-resolved coherent XUV-scattering N2 - XUV- and X-ray free-electron-lasers (FEL) combine short wavelength, ultrashort pulse duration, spatial coherence and high intensity. This unique combination of properties opens up new possibilities to study the dynamics of non-reversible phenomena with ultrafast temporal and nano- to atomic-scale spatial resolution. In this contribution we wish to present results of time-resolved experiments performed at the XUV-FEL FLASH (HASYLAB/Hamburg) aimed to investigate the nano-scale structural dynamics of laser-irradiated materials. Thin films and fabricated nano-structures, deposited on Si3N4-membranes, have been excited with ultrashort optical laser pulses. The dynamics of the non-reversible structural evolution of the irradiated samples during laser-induced melting and ablation has been studied in an optical pump - XUV-probe configuration by means of single-shot coherent scattering techniques (i.e. diffraction imaging [1]). In a first set of experiments we investigated the formation of laser induced periodic surface structures (LIPSS) on the surface of thin Si-films (thickness 100 nm). In a simplified view LIPPS are generated as a result of interference between the incident laser pulse and surface scattered waves which leads to a periodically modulated energy deposition. Time-resolved scattering using femtosecond XUV-pulses (with a wavelength of 13.5 nm and 7 nm) allowed us to directly follow LIPSS evolution on an ultrafast time-scale and with better than 40 nm spatial resolution. The observed scattering patterns show almost quantitative agreement with theoretical predictions [2] and reveal that the LIPSS start to form already during the 12 ps pump pulse. In the second set of measurements we studied picosecond and femtosecond laser induced ablation and disintegration of fabricated nano-structures. Correlations of coherent diffraction patterns measured at various time delays to the pattern of the undisturbed object show that order in the structure is progressively lost starting from short length scales. This structural rearrangement progresses at close to the speed of sound in the material. Under certain circumstances (e.g. adequate sampling) it became also possible to reconstruct real-space images of the object as it evolves over time [3]. The possibility of femtosecond single-shot imaging of ultrafast dynamic processes with nanoscale resolution provides yet more details of the physical processes involved. [1] H. N. Chapman et al. Nature Phys. 2, 839 (2006). [2] J. F. Young et al., Phys. Rev. B 27, 1155 (1983). [3] A. Barty et al. Nature Phot. 2, 415 (2008). T2 - Fall meeting of the materials research society 2009 CY - Boston, MA, USA DA - 2009-11-30 KW - Femtosecond laser ablation KW - Laser-induced periodic surface structures KW - Time-resolved coherent XUV scattering KW - Semiconductor KW - Silicon PY - 2010 DO - https://doi.org/10.1557/PROC-1230-MM05-03 N1 - Serientitel: Materials Research Society symposium proceedings – Series title: Materials Research Society symposium proceedings VL - 1230E IS - Paper 1230-MM05-03 SP - 1 EP - 6 AN - OPUS4-21438 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Rosenfeld, A. A1 - Grebing, C. A1 - Steinmeyer, G. A1 - Mailman, N. A1 - Botton, G.A. A1 - Haugen, H.K. T1 - Ablation and structural changes induced in InP surfaces by single 10 fs laser pulses in air N2 - Ablation of single-crystalline (100) indium phosphide wafer surfaces with single 10 fs Ti:sapphire laser pulses in air has been studied by means of complementary cross-sectional transmission electron microscopy, scanning force microscopy, and optical microscopy. A local protrusion of ~70 nm height is generated within the ablation craters for fluences exceeding 0.78 J/cm². This morphological feature has been studied in detail, revealing the material structure of the laser-affected zone and its spatial extent. The resolidified layer (60-200 nm thick) consists of polycrystalline grains (5-15 nm diameter) and is covered by an ~10 nm thick amorphous top layer. Interestingly, the sharp boundary of the solidified layer to the unaffected crystal underneath exhibits a Gaussian-like shape and does not follow the shape of the surface topography. Evidence is presented that the central crater protrusion is formed by near-surface optical breakdown, and that the absorption in the material transiently changes during the femtosecond-laser pulse. KW - Femtosecond laser ablation KW - Optical breakdown KW - Transmission electron microscopy KW - Semiconductor KW - Indium phosphide KW - Scanning force microscopy KW - Time-resolved measurements PY - 2009 UR - http://link.aip.org/link/?JAPIAU/106/074907/1 DO - https://doi.org/10.1063/1.3236630 SN - 0021-8979 SN - 1089-7550 VL - 106 SP - 074907-1 - 074907-7 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-20083 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Krüger, Jörg T1 - Probing the heat affected zone by chemical modifications in femtosecond pulse laser ablation of titanium nitride films in air N2 - A new approach is presented to quantify the so-called "heat affected zone" (HAZ) during femtosecond laser pulse processing. Ablation of titanium nitride (TiN) thin films (~3 μm thickness) by multiple femtosecond laser pulses (τ=130 fs, λ=800 nm) in air environment was studied by means of two different surface analytical methods both being sensitive to chemical alterations at the surface. Scanning Auger electron microscopy was applied for a visualization of the spatial distribution of specific elements (Ti, O) within the laser-modified areas. The chemical state of the irradiated surface was revealed by complementary x-ray photoelectron spectroscopy. Both methods were used for a depth-profiling chemical analysis (tracking the elements Ti, N, O, and C) using an Ar-ion beam for surface sputtering. In a narrow laser fluence range slightly below the ablation threshold of TiN significant superficial oxidation can be observed leading to the formation of substoichiometric TiO2-x. At fluences above the ablation threshold, an increased titanium concentration is observed within the entire ablation craters. Following upon sputter removal the elemental distribution into the depth of the nonablated material, the results allow an estimation of the heat-affected zone for femtosecond laser ablation in air environment. According to our analyses, the HAZ extends up to a few hundreds of nanometers into the nonablated material. KW - Femtosecond laser ablation KW - Heat affected zone KW - Titanium nitride KW - Scanning Auger electron microscopy KW - X-ray KW - Photoelektron spectroscopy PY - 2010 UR - http://link.aip.org/link/?JAP/107/054902 DO - https://doi.org/10.1063/1.3311552 SN - 0021-8979 SN - 1089-7550 VL - 107 IS - 5 SP - 054902-1 - 054902-5 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-20949 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Puerto, D. A1 - Siegel, J. A1 - Gawelda, W. A1 - Galvan-Sosa, M. A1 - Ehrentraut, L. A1 - Bonse, Jörn A1 - Solis, J. T1 - Dynamics of plasma formation, relaxation, and topography modification induced by femtosecond laser pulses in crystalline and amorphous dielectrics N2 - We have studied plasma formation and relaxation dynamics along with the corresponding topography modifications in fused silica and sapphire induced by single femtosecond laser pulses (800 nm and 120 fs). These materials, representative of high bandgap amorphous and crystalline dielectrics, respectively, require nonlinear mechanisms to absorb the laser light. The study employed a femtosecond time-resolved microscopy technique that allows obtaining reflectivity and transmission images of the material surface at well-defined temporal delays after the arrival of the pump pulse which excites the dielectric material. The transient evolution of the free-electron plasma formed can be followed by combining the time-resolved optical data with a Drude model to estimate transient electron densities and skin depths. The temporal evolution of the optical properties is very similar in both materials within the first few hundred picoseconds, including the formation of a high reflectivity ring at about 7 ps. In contrast, at longer delays (100 ps–20 ns) the behavior of both materials differs significantly, revealing a longer lasting ablation process in sapphire. Moreover, transient images of sapphire show a concentric ring pattern surrounding the ablation crater, which is not observed in fused silica. We attribute this phenomenon to optical diffraction at a transient elevation of the ejected molten material at the crater border. On the other hand, the final topography of the ablation crater is radically different for each material. While in fused silica a relatively smooth crater with two distinct regimes is observed, sapphire shows much steeper crater walls, surrounded by a weak depression along with cracks in the material surface. These differences are explained in terms of the most relevant thermal and mechanical properties of the material. Despite these differences the maximum crater depth is comparable in both material at the highest fluences used (16J/cm2). The evolution of the crater depth as a function of fluence can be described taking into account the individual bandgap of each material. KW - Femtosecond laser ablation KW - Plasma formation KW - Time-resolved microscopy KW - Dielectrics KW - Fused silica KW - Sapphire KW - Scanning force microscopy KW - Reflectivity measurements KW - Transmission measurements KW - Drude model PY - 2010 DO - https://doi.org/10.1364/JOSAB.27.001065 SN - 0740-3224 SN - 1520-8540 VL - 27 IS - 5 SP - 1065 EP - 1076 PB - Optical Society of America CY - Washington, DC AN - OPUS4-21167 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -