1,720,996 research outputs found
Deterministic sub-micron 2D grating structures on steel by UV-fs-laser interference patterning
No full textLarge area linear and crossed grating structures on steel surfaces are obtained by UV-femtosecond-laser ablation at 248 nm. High resolution on large areas is secured using a beam delivery system based on a two-grating interferometer. Thus, deterministic gratings with periods down to 330 nm and modulation depths of more than 100 nm are fabricated on tool steel and stainless steel. Areas of up to mm can be processed without stitching errors
A 100 mJ table-top short pulse amplifier for 248 nm using interferometric multiplexing
No full textA polarization multiplexing method (based on Sagnac interferometer's principle) was used in combination with a table-top wide aperture discharge pumped excimer amplifier to amplify femtosecond UV pulses. It is possible to optimize the operational conditions of the device within a wide range of input energies by changing the optical setup, while keeping the signal-to-noise ratio (short pulse - amplified spontaneous emission (ASE) ratio) of the pulses on a reasonably low value. The amplifier was tested for two different front ends. With similar to 40 muJ input energy similar to 50 mJ output energy was obtained in a 3-pass arrangement, and applying a seed pulse carrying an energy of around 2-3 mJ a maximum output energy of 100 mJ was reached in a single subpicosecond beam at 248 nm
Sub-micron patterning of solid materials with ultraviolet femtosecond pulses
No full textThe treatment of solid materials using subpicosecond laser pulses at 248 nm is studied. The potential of the combination of femtosecond pulse durations with ultraviolet wavelengths for precise material processing is demonstrated. Imaging techniques combined with diffractive optical elements are exploited for the fabrication of nanometer-scale features on practically all classes of materials including metals, semiconductors, and dielectrics. Two-dimensional periodic surface structures with excellent quality and reproducibility over large areas with feature sizes down to the 100 nm range are reached . An extension of this technique to transparent solids to reach defect sizes of a few hundreds of nanometers inside various materials is also possible. As a technical highlight, efficient drilling of a great number of holes with diameters below 500 nm through metal foils is demonstrated. Irradiation is performed using a UV laser system based on a Ti:Sapphire-Excimer hybrid device generating 300 fs pulses at 248 nm. Operation at 300 Hz (resulting in 10 W average output power) allows high speed machining, opening up new possibilities in industrial applications
Fabrication of SiO2 Phase Gratings by UV Laser Patterning of Silicon Suboxide Layers and Subsequent Oxidation
No full textUV transparent phase masks are used in various laser applications like fabrication of Bragg gratings in optical fibers or micro patterning by high power laser ablation. Normally they are fabricated by a costly lithographic process including e-beam writing and reactive ion etching. We propose a new fabrication method based on UV laser ablation. The process consists of three steps. First, a silicon suboxide coating (SiOx with x < 2) with a predefined thickness is deposited on a fused silica substrate. Second, due to its strong UV-absorption, this coating can be removed in defined areas by excimer laser ablation at 193 nm or 248 nm leading to the desired phase pattern in form of a binary depth profile. Third, by applying a thermal annealing process, the remaining SiOx-coating is oxidized to UV-transparent SiO2, resulting in a UV-grade surface relief element. The precisely defined interface between substrate and layer allows for ablation with exact depth control and perfect optical surface quality. Such SiO2 phase masks feature a large processed area, high efficiency for VUV to NIR radiation and can be customized e. g. for perfect zero order suppression. Applications of such phase gratings for materials processing with a UV-femtosecond laser are demonstrated. Using the phase gratings in a mask projection configuration, submicron patterns are created in a variety of materials.German Bundesministerium fur Wirtschaft und Technologie [16IN0174
Efficient submicron processing of metals with femtosecond UV pulses
No full textThe generation of submicron-sized holes on metal surfaces by applying femtosecond UV laser pulses was investigated. Different optical schemes based on a Schwarzschild-type reflective objective were used to reach optimized ablation quality and efficiency in different applications (hole ablation, through-hole drilling, generation of surface patterns consisting of holes, etc.). Submicron-sized holes and hole patterns were ablated onto metal surfaces and drilled through similar to5-mum-thick steel foils with 600-nm diameter on the output side. Using a special optical interferometric method, large-area surface processing of high-conductivity materials in the submicron regime was performed. Combining these techniques with the application of high-repetition-rate ultra-short UV laser sources, large-area sub-mum processing of all kinds of materials in industrial environments is possible
Sub-500-nm patterning of glass by nanosecond KrF excimer laser ablation
No full textThe surface of flint glass of type F2 is patterned by nanosecond KrF excimer laser ablation. Strong UV absorption provides a comparatively low ablation threshold and precise ablation contours. By using a two-grating interferometer, periodic surface patterns with 330 nm period and 100 nm modulation depth are obtained. This method enables the fabrication of 7 mmx13 mm wide grating areas with perfectly aligned grooves without the need of high-precision sample positioning. By double exposure, crossed gratings with adjustable depths in the two orthogonal directions can be generated
Fabrication of large-area grating structures through laser ablation
No full textA Grating-Interferometer setup is shown to be ideally suited for the fabrication of high quality periodic structures over large sample areas via laser ablation. Virtually perfect line structures with periods in the submicron range are easily obtained. The capabilities and limitations of the new setup are analyzed theoretically for nanosecond and femtosecond laser sources with different coherence properties. The theoretical predictions are verified experimentally for various sample materials.BMWi of Germany [16IN0205, 16IN0393
Table-top KrF amplifier delivering 270 fs output pulses with over 9 W average power at 300 Hz
No full textApplying the combination of a solid-state Ti:Sa laser system and a newly developed wide-aperture, discharge-pumped KrF amplifier, output pulses with over 9 W average power at 300 Hz have been achieved in a single output beam. The frequency-tripled seed pulses of the Ti:Sa system - delivering approximately 10 muJ energy at 248 nm - were amplified to over 30 mJ using a 3-pass off-axis amplification scheme. The optical set-up has been fitted to the amplifier's parameters, and stored-energy measurements were carried out with different parameters in order to optimize the operational conditions of the device for the highest average power
Ablation of microstructures applying diffractive elements and UV femtosecond laser pulses
No full textA new method for simple and economic fabrication of diffractive optical elements (DOEs) with three and four phase levels, by UV nanosecond (ns) laser ablation is presented. The technique is based on the combination of two sequentially generated complementary 2-level phase elements. During the fabrication, complete ablative removal of a highly absorbing silicon suboxide layer by pixelated backside illumination ensures the necessary high precision and optical quality. Full functionality of the new DOEs is demonstrated by fabricating micro-structures using UV femtosecond pulses.TEKES; TEKES, the Finnish Agency for Technology and Innovatio
Fabrication of SiO2 Phase Gratings by UV Laser Patterning of Silicon Suboxide Layers and Subsequent Oxidation
No full textUV transparent phase masks are used in various laser applications like fabrication of Bragg gratings in optical fibers or micro patterning by high power laser ablation. Normally they are fabricated by a costly lithographic process including e-beam writing and reactive ion etching. We propose a new fabrication method based on UV laser ablation. The process consists of three steps. First, a silicon suboxide coating (SiOx with x < 2) with a predefined thickness is deposited on a fused silica substrate. Second, due to its strong UV-absorption, this coating can be removed in defined areas by excimer laser ablation at 193 nm or 248 nm leading to the desired phase pattern in form of a binary depth profile. Third, by applying a thermal annealing process, the remaining SiOx-coating is oxidized to UV-transparent SiO2, resulting in a UV-grade surface relief element. The precisely defined interface between substrate and layer allows for ablation with exact depth control and perfect optical surface quality. Such SiO2 phase masks feature a large processed area, high efficiency for VUV to NIR radiation and can be customized e. g. for perfect zero order suppression. Applications of such phase gratings for materials processing with a UV-femtosecond laser are demonstrated. Using the phase gratings in a mask projection configuration, submicron patterns are created in a variety of materials.German Bundesministerium fur Wirtschaft und Technologie [16IN0174
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