Article
Materials Science, Multidisciplinary
Andreas Tuennermann, Carsten Momma, Stefan Nolte
Summary: Ultrashort pulse lasers have been widely used in precise micromachining. This article presents a brief perspective on the development of this innovative technology from the 1990s until today.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2023)
Review
Materials Science, Multidisciplinary
Yue Lu, Yun-Fei Li, Gong Wang, Yu Yu, Zhenxu Bai, Yulei Wang, ZhiWei Lu
Summary: Transparent hard materials with excellent characteristics such as high hardness, high transparency, corrosion resistance, and high temperature resistance have found applications in microfluidic substrates even in harsh environments. The traditional contact processing method for microchannel structures in transparent hard materials lacks processing efficiency and quality. Femtosecond laser processing, with its non-contact nature, no thermal damage, and high accuracy, provides a promising approach for fabricating microchannels in transparent hard materials. This review summarizes recent advances in femtosecond laser processing of transparent hard materials to form microchannel structures, including the reaction mechanism, processing methods, and obtained microchannel structures. The potential applications of microchannel structures in microfluidic fields, such as optical inspection and biochemical reactions, are also discussed.
ADVANCED MATERIALS TECHNOLOGIES
(2023)
Article
Engineering, Electrical & Electronic
Khaled Barhoum, Alena S. Shishkina, Roman A. Zakoldaev, Olga V. Andreeva
Summary: This study proposes a novel method for fabricating microchannels in two-phase glass using femtosecond direct laser writing (FDLW) and chemical etching. Different pulse durations, laser powers, and scanning speeds were used to create microchannels with varying widths and layer properties. After chemical etching, the resulting microchannels exhibited highly uniform morphology, high aspect ratio, and a pronounced refractive index surrounding layer, making them potentially suitable as waveguide layers.
OPTICAL AND QUANTUM ELECTRONICS
(2023)
Article
Chemistry, Analytical
Weiliang Chen, Jichao Gao, Jie Tian, Jingyu Zhang
Summary: In situ fluorophores were induced on polyvinyl alcohol (PVA) bulk materials by direct femtosecond laser writing, allowing for various applications such as sensors, data encryption, and water detection. The reversible and irreversible switching properties of laser-induced fluorophores were utilized to demonstrate a data encryption scheme and a burn after reading technique.
Article
Polymer Science
Kay Bischoff, Dominik Muecke, Gian-Luca Roth, Cemal Esen, Ralf Hellmann
Summary: In this study, we report on the laser ablation of cyclic olefin copolymer using an amplified ultrashort pulsed laser in the ultraviolet spectral range. The results demonstrate high ablation depth, excellent surface roughness, and increasing ablation efficiencies with increasing fluence. Comparing with an infrared laser wavelength, UV ablation shows significant advantages in terms of ablation efficiency, surface roughness, and quality. This study provides an efficient and qualitative tool for the laser machining of cyclic olefin copolymer using high-power UV ultrashort pulsed lasers.
Article
Chemistry, Analytical
Pawel Koziol, Piotr Jaworski, Karol Krzempek, Viktoria Hoppe, Grzegorz Dudzik, Fei Yu, Dakun Wu, Meisong Liao, Jonathan Knight, Krzysztof Abramski
Summary: This study demonstrated the fabrication of microchannels in a nodeless antiresonant hollow-core fiber (ARHCF) using femtosecond laser cutting, improving gas flow into the fiber core. Experimental results showed low transmission losses and the flexibility of the process. The maximum bending radius for the ARHCF with the processed microchannel was experimentally determined to be 15 cm without causing breaking.
Article
Engineering, Industrial
Astrid Sassmannshausen, Andreas Brenner, Johannes Finger
Summary: Ultrafast pulse laser polishing can achieve fine surface polishing effects by reallocating material from peaks to valleys. Experiments on 1.2738 tool steel show that polishing can significantly reduce surface roughness, achieving a polishing rate of 12.15 cm(2)/min.
JOURNAL OF MATERIALS PROCESSING TECHNOLOGY
(2021)
Review
Optics
Qiandong Ran, Hao Li, Wonkeun Chang, Qijie Wang
Summary: This paper reviews the latest advances in self-compression techniques without dispersion compensation optics for high-energy few-cycle pulse generation over the past two decades. Various experimental approaches and their potential applications in generating extremely intense optical fields for strong-field physics research are discussed.
LASER & PHOTONICS REVIEWS
(2023)
Article
Chemistry, Physical
Stefan Rung, Niklas Haecker, Ralf Hellmann
Summary: In this study, a comprehensive investigation on laser ablation and micromachining of alumina using a high-power ultrashort-pulsed laser was conducted. The optimal process strategy was determined and discussed based on the variation of laser parameters such as power, pulse duration, repetition rate, and spatial pulse overlap. The results showed that the highest ablation efficiency and ablation rate were achieved at high repetition rate and short pulse duration, while the surface roughness was predominantly affected by the applied laser fluence.
Article
Chemistry, Analytical
Julian Zettl, Cemal Esen, Ralf Hellmann
Summary: This article discusses the laser turning process of rotational symmetric, cylindrical components using ultrashort laser pulses. By considering the geometrical conditions and the resulting energy distribution, process predictions and potential optimizations can be made. The formation of laser spot on the cylindrical surface of the work piece and the positioning of the laser beam relative to the rotation axis are particularly emphasized.
Article
Optics
Angel Rodriguez, Ana J. Lopez, Javier Lamas, Alicia Moreno, Alberto Ramil
Summary: The paper presents a robot-assisted laser cleaning system that can automatically process 3D objects with any geometry. The system integrates a femtosecond pulse laser, a 6 DOF robotic arm, and a laser profilometer to capture the geometry of the workpiece. It performs an automatic procedure to generate cleaning paths and accurately targets each point on the surface. Experimental results demonstrate the improved efficiency of automatic laser cleaning with this system.
OPTICS AND LASERS IN ENGINEERING
(2023)
Review
Optics
Xinyang Su, Ruixue Zhu, Bolin Wang, Yu Bai, Tao Ding, Tianran Sun, Xing Lu, Jiying Peng, Yi Zheng
Summary: This paper summarizes the developments in mid-infrared (MIR) ultrafast laser generation and discusses the methods and theoretical models for generating 8-20 μm MIR ultrafast laser pulses via difference frequency generation (DFG). Furthermore, the feasibility of MIR power scaling using nonlinear-amplification DFG and methods for measuring the power of DFG-based MIR are analyzed from the author's perspective.
Review
Chemistry, Physical
Bakhtiar Ali, Igor V. Litvinyuk, Maksym Rybachuk
Summary: Ultra-fast femtosecond lasers offer a unique technological opportunity for precise and efficient micromachining, with minimal thermal damage. The application of fs-laser technology in micromachining diamond shows promising prospects but also faces challenges and opportunities for further development.
Article
Multidisciplinary Sciences
T. Janda, T. Ostatnicky, P. Nemec, E. Schmoranzerova, R. Campion, V. Hills, V. Novak, Z. Soban, J. Wunderlich
Summary: To develop ultra-high frequency and energy-efficient electronic devices, a fast and scalable approach to switch magnetic bits is required. By utilizing spin currents generated by spin-orbit interaction at ferromagnetic/non-magnetic interfaces, magnetization switching can be achieved.
SCIENTIFIC REPORTS
(2022)
Review
Optics
Jia-Wei Tan, Gong Wang, Yunfei Li, Yu Yu, Qi-Dai Chen
Summary: Micro-optical components have significant potential applications in imaging, optical fiber communication, and aerospace due to their small size, light weight, and flexible design. Fabricating micro-optical components on hard brittle materials is crucial for improving stability and expanding the optical transmission range. This study reviews recent advances in refractive/diffractive micro-optical components using femtosecond laser processing technologies, and summarizes their applications in imaging, sensing, display, and integration, highlighting the challenges and outlook of femtosecond laser processing technologies for micro-optical components.
LASER & PHOTONICS REVIEWS
(2023)
Article
Polymer Science
Yannick L. Wencke, Yunus Kutlu, Malte Seefeldt, Cemal Esen, Andreas Ostendorf, Gerrit A. Luinstra
Summary: The facile manufacture of PA12 MWCNT/silica nanocomposite powders through a high energy mixing process enables the generation of 3D objects using Laser Polymer Deposition. The built parts exhibit mechanical properties comparable to 10%-20% of the bulk material, with main mechanical failure mechanisms identified as partially unmolten particles and voids. The mechanical properties are improved with low additive content, and electronic conductivity can be achieved through the formation of a MWCNT network.
JOURNAL OF APPLIED POLYMER SCIENCE
(2021)
Article
Optics
Simon Schwarz, Stefan Rung, Cemal Esen, Ralf Hellmann
Summary: The study on micromilling cavities into fused silica using a femtosecond laser showed that increasing the number of pulses per burst led to increased depth per layer and ablation efficiency. The maximum ablation efficiency achieved in the experiments was 3.05 mm(3)/min/W for a burst number of 10, which was 7.4 times higher than for the non-burst condition.
Article
Chemistry, Physical
David Sommer, Dominik Pape, Cemal Esen, Ralf Hellmann
Summary: This study reports on the milling and tool wear characteristics of hybrid additive manufacturing. It is found that flank wear is the dominant wear characteristic, showing a typical S-shaped dependence over utilization period. The width of flank wear land is measured and correlated to the surface roughness of milled 3D-printed parts, revealing that a superior surface roughness below 3 μm is achievable for hybrid additive manufacturing with flank wear levels up to 100 μm. Furthermore, the milling process is improved by optimizing the finishing tool start position and the number of afore-built layers, resulting in an increased maximum millable angle for undercut surfaces of 3D-printed parts.
Article
Optics
Daniel Franz, Tom Haefner, Tim Kunz, Gian-Luca Roth, Stefan Rung, Cemal Esen, Ralf Hellmann
Summary: This study reports on a hybrid laser scanning system that combines acousto-optical deflectors with galvanometer scanners for ultra-short pulse laser material processing. The system exhibits high ablation roundness and positioning speed, enabling highly dynamic and extremely precise laser beam positioning in a large processing area.
APPLIED PHYSICS B-LASERS AND OPTICS
(2022)
Article
Chemistry, Analytical
Max Schleier, Benedikt Adelmann, Cemal Esen, Ralf Hellmann
Summary: We propose an in situ process monitoring approach for remote fiber laser cutting, which utilizes a high-speed camera and a specifically designed image processing algorithm to distinguish between complete and incomplete cuts. The camera-based monitoring system is suitable for high-power fiber lasers and can accurately evaluate the size of the melt pool and the emitted sparks during the cutting process.
Article
Chemistry, Physical
Daniel Franz, Tom Haefner, Tim Kunz, Gian-Luca Roth, Stefan Rung, Cemal Esen, Ralf Hellmann
Summary: In this study, a comprehensive investigation on laser percussion microvia drilling of FR-4 printed circuit board material using ultrashort pulse lasers is carried out. The effects of different laser parameters on the quality of microvias are analyzed, and the optimal conditions are identified.
Article
Polymer Science
Kay Bischoff, Dominik Muecke, Gian-Luca Roth, Cemal Esen, Ralf Hellmann
Summary: In this study, we report on the laser ablation of cyclic olefin copolymer using an amplified ultrashort pulsed laser in the ultraviolet spectral range. The results demonstrate high ablation depth, excellent surface roughness, and increasing ablation efficiencies with increasing fluence. Comparing with an infrared laser wavelength, UV ablation shows significant advantages in terms of ablation efficiency, surface roughness, and quality. This study provides an efficient and qualitative tool for the laser machining of cyclic olefin copolymer using high-power UV ultrashort pulsed lasers.
Article
Chemistry, Physical
Stefan Kefer, Julian Zettl, Cemal Esen, Ralf Hellmann
Summary: This article introduces two new methods for micromachining rotational-symmetric sapphire workpieces using femtosecond laser. The first method can produce sapphire fibers with a diameter of 50 μm, while the second method can produce sapphire fibers with a diameter of 90 μm and a length of up to 20 cm. These methods provide an innovative all laser-based approach for the fabrication or microstructuring of sapphire optical devices, and offer a promising alternative to chemical processes.
Article
Chemistry, Physical
Mustafa Ayna, Johannes Spille, Yahya Acil, Jan-Tobias Weitkamp, Jorg Wiltfang, Cemal Esen, Aydin Guelses
Summary: The aim of this experimental study was to compare the surface alterations of titanium and titanium-zirconium alloy implants after Er:YAG laser irradiation, particularly in terms of thread pitch topography. The results showed that Roxolid (R) alloy could maintain its surface topography at lower energy levels, but higher energy levels were required to smoothen the surface.
Article
Chemistry, Physical
David Sommer, Cemal Esen, Ralf Hellmann
Summary: We conducted a comprehensive study on the mechanical properties of maraging steel body-centred cubic lattice structures fabricated by a hybrid additive manufacturing technology that combines laser powder bed fusion with in situ high-speed milling. Surface modifications can improve the mechanical behavior of additive manufactured components. Different hybrid additive manufacturing technologies have been designed using additive and subtractive processes, aiming to improve process quality.
Article
Chemistry, Physical
Christian Lutz, Jonas Helm, Katrin Tschirpke, Cemal Esen, Ralf Hellmann
Summary: This study reports on laser drilling borehole arrays using ultrashort pulsed lasers, with a focus on reducing inadvertent heat accumulation across the workpiece by optimizing the drilling sequence. Evolutionary algorithms are employed for optimization, and their results are verified through thermal simulation and experimental evaluation. Multi-spot approaches using a spatial light modulator are utilized to enhance process efficiency, but careful selection of spatial distribution and sequence is necessary to limit local heat input.
Article
Chemistry, Multidisciplinary
Kay Bischoff, Cemal Esen, Ralf Hellmann
Summary: This study demonstrates the preparation of finely dispersed copper(II) oxide nanosuspensions as precursors for reductive laser sintering (RLS) and discusses different methods for particle dispersion. Nanosuspensions prepared by high-energy ball milling exhibit a higher proportion of fine particles and a more uniform particle size distribution, which can be used to produce high-quality copper layers.
Article
Nanoscience & Nanotechnology
Jan Marx, Jochen Tenkamp, Frank Walther, Cemal Esen
Summary: This study reports on the combination of non-diffracting Bessel beams and ultra-short pulsed laser ablation for generating micro-channels, analyzing optimal processing conditions by investigating laser power, exposure cycles, and sample axial position. Compared to Gaussian Beam processing, channels processed with Bessel beams exhibit more rectangular geometry.
JOURNAL OF LASER MICRO NANOENGINEERING
(2022)
Article
Optics
Gordon Zyla, Alexander Kovalev, Cemal Esen, Andreas Ostendorf, Stanislav Gorb
Summary: This study successfully utilized 3D printing by two-photon polymerization to engineer biomimetic surface structures inspired by blue-winged butterflies. The printed structures displayed angle-insensitive optical properties similar to the Morpho wings. The researchers also analyzed the morphology and optical properties of the biological and engineered specimens and compared the coloration of biomimetic surfaces with that of the Morpho butterfly.
JOURNAL OF OPTICAL MICROSYSTEMS
(2022)
Proceedings Paper
Engineering, Electrical & Electronic
Philipp Maack, Alexander Kanitz, Jan Hoppius, Jannis Koehler, Cemal Esen, Andreas Ostendorf
Summary: Pulsed laser ablation in liquid reduces particle redeposition and can potentially be an alternative to laser processing under atmospheric conditions. However, the complex interaction between hot molten material, plasma, and liquid can cause persistent changes in surface chemistry.
LASER-BASED MICRO- AND NANOPROCESSING XVI
(2022)