Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).
Please note that all times are shown in the time zone of the conference. The current conference time is: 4th Aug 2021, 01:59:54am CEST
Session Chair: Clemens Roider, Institute of Photonic Technologies (LPT), Germany
Location:Room 3 ICM
1:30pm - 1:45pm
Optical system for multi Bessel beam high power ultrashort pulsed laser processing using a spatial light modulator
Christian Lutz1, Simon Schwarz1, Stefan Rung1, Jan Marx2, Cemal Esen2, Ralf Hellmann1
1University of Applied Science Aschaffenburg, Germany; 2Ruhr University Bochum, Germany
We report on an optical setup for multi Bessel beam processing combining refractive axicon and spatial light modulator technology. Based on their particular beam profile, Bessel beams exhibit various advantages over conventional Gaussian beams for ultrashort pulsed laser processing. Especially for micromachining of transparent materials, applications like drilling micro-holes or the generation of voids benefit from the increased focal length of a Bessel beam. In addition, on account of the significantly increased average output power of industrial ultrashort pulsed lasers over the last years, there is a high demand on multi spot applications for using the available laser power in efficient production processes. Our optical concept combines the dynamic possibilities of beam splitting using spatial light modulator with the benefits of Bessel beams facilitating multi Bessel beam processing.
1:45pm - 2:00pm
Water jet guided laser as a versatile tool for industrial turning applications
The Laser Microjet® technology couples a nanosecond pulsed Nd:YAG laser into a thin cylindrical water jet. It comes with numerous advantages such as a reduced heat affected zone and a parallel energy beam over several centimeters. Laser turning is in high demand to process hard or fragile materials allowing the production of complex solids of revolution. However, conventional laser must still contend with heat management, as well as the energy needed to ablate the whole volume. The LMJ technology can both cut-out large section in facets as well as fully turn the surface by ablation. Effective and efficient strategies of roughing and finishing become therefore possible and can yield high throughput. A surface roughness with Ra as low as 0.2µm can be reached. This paper presents several water jet guided laser turning strategies and their implementation in challenging industrial turning applications.
2:00pm - 2:15pm
Automated synthesis of colloidal nanoparticles powered by microchip lasers
Tobias Bessel, Sarah Dittrich, Bilal Gökce, Stephan Barcikowski, Friedrich Waag
Technical Chemistry I and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Germany
Energy and health, two topics with continuing high relevance for our society, which require intensive R&D. Nanoparticles, with their unique properties, already make an important contribution to both fields and will play an even more essential role in the future. Access to high-quality nanoparticles for R&D is still difficult, especially when high purity and material diversity are required. Pure colloidal nanoparticles of numerous combinations of particle material and dispersion medium become available by pulsed laser ablation. Novel microchip lasers now enable the transfer of the synthesis method from the laser lab to any R&D lab as a compact, easy-to-use machine. The low-power lasers impress with unprecedented power efficiency in the laser synthesis of colloids. In addition, innovative solutions in measurement and control technology make full automation of the nanoparticle production possible.
2:15pm - 2:30pm
Mastering micro-filamentation for semiconductor-metal ultrafast laser welding
Maxime Chambonneau1, Qingfeng Li1, Vladimir Yu. Fedorov2, Markus Blothe1, Stelios Tzortzakis2, Stefan Nolte1,3
1Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Germany; 2Science Program, Texas A&M University at Qatar, Qatar; 3Fraunhofer Institute for Applied Optics and Precision Engineering IOF, Germany
While ultrafast laser welding is a proven technique for bonding a wide variety of materials together, it has no equivalent for semiconductor-metal, which would be particularly interesting for applications in microelectronics. We explain this nonexistence by the strong nonlinear propagation effects in the semiconductor. Nonlinear propagation imaging shows significant nonlinear focal shift values, in excellent agreement with self-focusing theory. We demonstrate that this nonlinear focal shift leads to a drastic depletion of the light intensity at the exit surface of silicon, at levels insufficient for laser welding applications. By determining and precompensating the nonlinear focal shift, the energy delivered at the interface is optimized, leading to the very first demonstration of semiconductor-metal laser welding. A maximum shear joining strength of 2.2 MPa is measured between the samples, which is compatible with applications. Ultimately, material analyses of the welds shed light on the underlying physical mechanisms.