111 research outputs found

    Low Temperature Optodic Bonding for Integration of Micro Optoelectronic Components in Polymer Optronic Systems

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    AbstractLarge area, planar optronic systems based on flexible polymer substrates allow a reel-to-reel mass production, which is widely adopted in modern manufacturing. Polymer optronic systems are fully integrated with micro optical and optoelectronic components as light sources, detectors and sensors to establish highly functional sensor networks. To achieve economical production, low-cost polymer sheets are employed. Since they are mostly thermally sensitive, this requires a restricted thermal loading during processing. Furthermore, a short process time improves production efficiency, which plays a key role in manufacturing processes. Thus, in this contribution we introduce a new bare chip bonding technique using light instead of heat to meet both requirements. The technique is based on the conventional flip-chip die bonding process. Ultraviolet radiation curing adhesives are applied as bonding material, accordingly a sideway ultraviolet radiation source, a so-called optode, is designed. Before implementing the concept, the light distribution in the contact spot is simulated to examine the feasibility of the solution. Besides, we investigate two different UV lamps regarding induced thermal influence on polymer substrate to choose one to be employed in the optode. Process factors, irradiation intensity and irradiation time are studied. Based on these results, the mechanical and electrical reliability of the integrated components is finally evaluated

    Laser-based powder bed fusion of Ti-6Al-4V structures with different surface-area-to-volume ratios in oxygen-reduced and oxygen-free environment

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    Titanium alloys, such as Ti-6Al-4V, are particularly susceptible to oxidation, which is why their processing in the laser-based powder bed fusion process is carried out conventionally in a protective gas atmosphere. However, this atmosphere still contains critical residual oxygen levels, which are to be eliminated as part of a new approach. This approach envisages doping the argon protective gas atmosphere with small amounts of the highly reactive gas silane (ratio < 1:1000). The residual oxygen content is particularly critical in filigree and thin-walled structures that have a high surface-area-to-volume ratio and are a typical field of application for this additive manufacturing process. Therefore, this work focuses on the manufacturing of Ti-6Al-4V structures with different surface-area-to-volume ratios in conventional argon (< 200 ppm residual oxygen) and argon-silane atmospheres (< 10-14 ppm residual oxygen) on an innovative laboratory machine. After processing, the specimens are analyzed for surface topography, microstructure, and Vickers hardness. In addition, energy-dispersive X-ray spectroscopy and X-ray diffraction measurements are carried out to further investigate the chemical composition and present phases in the as-built specimens. The influence of the different atmospheres and their residual oxygen content, the surface-to-volume ratio, and possible interactions between them are discussed

    Functional coatings of sol-gel on glass substrate using CO2 laser irradiation

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    Often Glass products achieve their component functionality only by a specific surface finishing, such as coating or patterning. Compared to vacuum based CVD and PVD coating techniques, the equipment for wet-chemical deposition of sol-gels is less expensive. Heat is needed for a chemical reaction to cure gels and form solid functional layers. In this study, sols with titanium and zirconium were applied on glass substrates by dip coating. The investigated layer thicknesses were in the range between 320 nm and 650 nm. The gel layers were annealed with CO2 laser radiation. Different scanning speeds and laser powers were investigated. Microscope images were used to compare the laser-annealed layers with oven-annealed layers. To conclude, the oven-process can be substituted by laser annealing and additionally enables local patterning. This allows gradient coating solutions for architecture applications

    Low noise 400 W coherently combined single frequency laser beam for next generation gravitational wave detectors

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    Design studies for the next generation of interferometric gravitational wave detectors propose the use of low-noise single-frequency high power laser sources at 1064 nm. Fiber amplifiers are a promising design option because of their high output power and excellent optical beam properties. We performed filled-aperture coherent beam combining with independently amplified beams from two low-noise high-power single-frequency fiber amplifiers to further scale the available optical power. An optical power of approximately 400 W with a combining efficiency of more than 93% was achieved. The combined beam contained 370 W of linearly polarized TEM00-mode and was characterized with respect to the application requirements of low relative power noise, relative beam pointing noise, and frequency noise. The noise performance of the combined beam is comparable to the single amplifier noise. This represents, to our knowledge, the highest measured power in the TEM00-mode of single frequency signals that fulfills the low noise requirements of gravitational wave detectors

    Thermoforming of planar polymer optical waveguides for integrated optics in smart packaging materials

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    The innovations in smart packaging will open up a wide range of opportunities in the future. This work describes the processing of additive manufactured and planar integrated polymer optical waveguides for use in smart packaging products. The previously published combination of flexographic and Aerosol Jet printing is complemented by thermoforming and thus creates three-dimensional integrated multimode waveguides with optical attenuation of 1.9 dB/cm ± 0.1 dB/cm @ 638 nm. These properties will be the basis to develop smart applications in packaging materials

    Juxtaposition of Spin Freezing and Long Range Order in a Series of Geometrically Frustrated Antiferromagnetic Gadolinium Garnets

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    Specific heat measurements in zero magnetic field are presented on a homologous series of geometrically frustrated, antiferromagnetic, Heisenberg garnet systems. Measurements of Gd3Ga5O12, grown with isotopically pure Gd, agree well with previous results on samples with naturally abundant Gd, showing no ordering features. In contrast, samples of Gd3Te2Li3O12 and Gd3Al5O12 are found to exhibit clear ordering transitions at 243 mK and 175 mK respectively. The effects of low level disorder are studied through dilution of Gd3+ with non-magnetic Y3+ in Gd3Te2Li3O12. A thorough structural characterization, using X-ray diffraction, is performed on all of the samples studied. We discuss possible explanations for such diverse behavior in very similar systems.Comment: Accepted for publication in Physical Review
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