Fraunhofer-Publica
The Fraunhofer-Publica has been successfully documenting the research results of the Fraunhofer-Gesellschaft for over 30 years. The platform enables the collaborative linking of research-relevant objects and disseminates within the international scientific community.
The Fraunhofer-Publica thus fulfils its responsibility to promote the transfer of knowledge and know-how to industry and society.
Categories
Research outputs
As an application-oriented research organisation, Fraunhofer aims to conduct highly innovative and solution-oriented research - for the benefit of society and to strengthen the German and European economy.
Projects
Fraunhofer is tackling the current challenges facing industry head on. By pooling their expertise and involving industrial partners at an early stage, the Fraunhofer Institutes involved in the projects aim to turn original scientific ideas into marketable products as quickly as possible.
Researchers
Scientific achievement and practical relevance are not opposites - at Fraunhofer they are mutually dependent. Thanks to the close organisational links between Fraunhofer Institutes and universities, science at Fraunhofer is conducted at an internationally first-class level.
Institutes
The Fraunhofer-Gesellschaft is the leading organisation for applied research in Europe. Institutes and research facilities work under its umbrella at various locations throughout Germany.
Recent Additions
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PublicationSelective laser-induced etching for novel 3D microphotonic devices( 2024)In this work, we evaluate the advantages and limitations of the Selective Laser-induced Etching (SLE) process for the fabrication of novel three-dimensional microresonator structures. Microresonators are resonant optical structures with the ability to store light of a specific wavelength. They are used as non-linear optical components, in sensors or even in integrated photonic devices. These structures are characterized by the optical quality factor Q as a measure of the optical storage capabilities. Q is significantly influenced by a high-quality optical surface with low surface roughness. In addition to surface quality and small dimensions, from tens of microns to millimeters, high optical nonlinearity is a key requirement in these fields. The fabrication of 3D fused silica parts fulfilling these requirements is an ongoing challenge in the field of microfabrication in quantum technology. The SLE process is used to fabricate three-dimensional parts of transparent materials such as fused silica with a high degree of geometric freedom in a two-step process. In the first step, a model of the part is written into the material using Ultrashort Pulse (USP) laser radiation. In the second step, the laser-written shape is wet-chemically etched in aqueous KOH to expose the part. The fabrication of 2D disk microresonators with high Q-factors is evaluated by studying the surface roughness of the SLE process followed by polishing. The polished samples are characterized and Q-factors >107 are achieved. In addition, the extent to which dimensions and geometry differ between design and real SLE components is analyzed. The SLE process will thus be investigated as a possible process for the future fabrication of three-dimensional microresonators.
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PublicationHow to Measure the Greenness of Chemicals? A Case Study on Butadiene Production Applying Green Metrics and Life Cycle Assessment( 2024)The greenness of naphtha- and bioethanol-based butadiene was compared using green metrics (GM) and life cycle assessment (LCA). GM provide predominantly qualitative results, showing advantages for bioethanol-based butadiene. LCA indicates benefits of bioethanol-based butadiene in terms of global warming and fossil resource consumption, but drawbacks in acidification, eutrophication, radiation, land use, ozone depletion, particulate matter, ozone formation, metal depletion, and freshwater consumption. When comparing both assessment approaches used, LCA offers a more comprehensive environmental assessment while GM is limited to a smaller section of the value chain but address additional aspects such as safety of chemicals.
Most viewed
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PublicationMeasurement of Local Recombination Activity in High Diffusion Length Semiconductors( 2023)We present a conceptual approach for the localisation and characterisation of local sites of recombination in high diffusion length semiconductors under photovoltaic field conditions. While established imaging techniques operate in this very regime of uniform "1 sun" illumination, inevitable lateral diffusion of charge carriers veils the origin and severity of localised recombination sites. To reduce this limitation due to lateral diffusion the natural choice is using focussed charge carrier excitation and detection in combination with scanning the specimen. The resulting photoluminescence intensity maps are of high spatial resolution and may be composed of a superposition of a multitude of recombination active defects influencing each other due to the high bulk diffusion length. We demonstrate the feasibility of a self-consistent calibration of the setup quantum efficiency in such experimental condition which delivers a charge carrier density map in absolute units. A solution is presented to disentangle the superposition of local sites of recombination to isolate the actual recombination activity of every site. We demonstrate the feasibility of the approach experimentally on the high diffusion length semiconductor silicon.
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