A5031875697- Laser Material Processing Techniques
- Advanced Surface Polishing Techniques
- Laser-induced spectroscopy and plasma
- Laser-Ablation Synthesis of Nanoparticles
- Surface Roughness and Optical Measurements
- Photonic and Optical Devices
- Diamond and Carbon-based Materials Research
- Nonlinear Optical Materials Studies
- Optical Coatings and Gratings
- Semiconductor Lasers and Optical Devices
- Silicon Nanostructures and Photoluminescence
- Laser Design and Applications
- Advanced Fiber Optic Sensors
- Ocular and Laser Science Research
- Adhesion, Friction, and Surface Interactions
- Photonic Crystals and Applications
- Advanced Fiber Laser Technologies
- Gold and Silver Nanoparticles Synthesis and Applications
- Nanowire Synthesis and Applications
- Silicone and Siloxane Chemistry
- Semiconductor materials and devices
- Synthesis and properties of polymers
- Surface Modification and Superhydrophobicity
- Thin-Film Transistor Technologies
- Optical Coherence Tomography Applications
Institut für Nanophotonik
2015-2024
Laser Zentrum Hannover
2007
University of Göttingen
1999
A versatile model for ultraviolet (UV) laser ablation of polymers is presented, which very successfully applied to the calculation a variety different properties this process, including influence plume attenuation dynamics. The polymer described as system chromophores with two possible electronic states. based on combination photothermal decomposition and photodissociative bond breaking in electronically excited state. Laser induced chemical modifications are incorporated via absorption...
A laser is a very sharp tool, so to speak, for carving materials at the nanoscale, but involves many poorly understood, nonequilibrium processes. The authors' investigation combines an advanced experimental technique, using UV realize much finer structures than possible visible beam, with atomistic-continuum computational method that allows direct comparison of simulations empirical results. This provides both tools and understanding needed develop nanotechnology diverse ends in e.g....
A new two-step method, facilitating the rapid generation of super-hydrophobic surface structures via parallel laser processing followed by a replica injection molding is reported. self-made fused silica-based diffractive optical element (DOE) applied to distribute energy into 25×25 dot matrix. This DOE used as transmission mask for ablation metal molds, applying short-pulse UV pulses. In subsequent process step, replicas processed stamp are produced variothermal molding, enabling mass...
Abstract Understanding the mechanisms and controlling possibilities of surface nanostructuring is crucial interest for both fundamental science application perspectives. Here, we report a direct experimental observation laser-induced periodic structures (LIPSS) formed near predesigned gold step edge following single-pulse femtosecond laser irradiation. Simulation results based on hybrid atomistic-continuum model fully support observations. We experimentally detect nanosized features with...
In situ surface imaging for nondestructive evaluation (NDE) by optical coherence tomography (OCT) before, during, and after ablative laser processing is presented. Furthermore, it shown that the ability of in characterization beneficial samples such as fibers, which are difficult to handle standard analysis. Surface images taken OCT compared with these common analysis tools scanning electron microscopy (SEM), reflected-light, confocal microscopy. An axial resolution ∼126 nm detection a...
The reflectivity of noble metals can dramatically change upon ultrashort laser irradiation due to the heating $d$ electrons high temperatures. Knowledge resulting transient optics is fundamental for determining and controlling absorbed energy. In this work, high-accuracy self-reflectivity measurements are performed interpreted using a theory space-resolved time-resolved energy absorption dissipation. combined approach yields gold in dependence on incident fluence wide spectral range.
Abstract Polymers which are not absorbing at the wavelength of irradiation may be sensitized by doping with low concentrations suitable compounds for laser‐induced surface modification and ablation. In present study this approach is applied to ablation PMMA 308 nm (XeCl* excimer laser). Substituted phenyltriazene diphenyltriazene compounds, two pentazadienes a hexazadiene tested as promoters in 1, 2, 5 wt.‐%, respectively. From all these nitrogen released upon photochemical decomposition. A...
The fabrication of SERS-active substrates, which offer high enhancement factors as well spatially homogeneous distribution the enhancement, plays an important role in expansion surface-enhanced Raman scattering (SERS) spectroscopy to a powerful, quantitative, and noninvasive measurement technique for analytical applications. In this paper, novel method substrates by laser treatment 20, 40, 60 nm thick gold 40 silver films supported on quartz glass is presented. Single 308 UV-laser pulses...
We show that a periodic nanostructure patterned into polymeric or indium tin oxide (ITO) surface is capable of aligning liquid crystal (LC) molecules. Gratings different depths were created on thin ITO surfaces with submicron and micron periods by superposition ultraviolet plane waves. The depth the gratings was varied changing fluence laser. This method allows to pattern orientations over small areas does not suffer from disadvantages rubbing based alignment methods. LC tested forming...