Jena, Germany


Jena, Germany
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Taccheo S.,University of Swansea | D'Andrea C.,Polytechnic of Milan | Bassi A.,Polytechnic of Milan | Cubeddu R.,Polytechnic of Milan | And 6 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

We report on generation of blue light exploiting high-order mode propagation in a microstructured fiber pumped by a Ti:Sapphire close to the zero-dispersion wavelength of the first high-order mode. An new interesting regime was observed with axial offset pump. With 230 mW of incident pump power we generated over 3 mW in the 450-510 nm window achieving 50 μW/nm power density. In a final round of measurements we were able to show generation of a peak at 350 nm. This complex regime has still to be fully investigated but we believe an optimized fiber design will allow to efficiently extend the operation of Ti:Sapphire laser to UV/blue wavelength region. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Grutzner C.,RWTH Aachen | Bemmann J.,University of Bonn | Berking J.,Free University of Berlin | Frechen M.,Leibniz Institute For Angewandte Geophysik | And 9 more authors.
Journal of Geophysics and Engineering | Year: 2012

The Orkhon Valley in the Central Mongolia was included in the World Heritage list in 2004. It hosts multiple archaeological sites from Palaeolithic to recent times, which can contribute to the reconstruction of settlement history in this part of the Eurasian Steppe landscape. Almost 100 archaeological sites from prehistoric and historic times including ramparts and khirigsuurs were investigated in five field campaigns from 2008 to 2010 in the middle and upper Orkhon Valley. One site, MOR-2 (Dörvölzhin), proved especially difficult to date due to the lack of sufficient archaeological surface finds, and its role within a manifold of walled enclosures from different times in the study area remained unclear. Therefore, different techniques of archaeology, geophysics and geoarchaeology were combined at MOR-2 in order to determine a comprehensive picture about its timing, archaeological meaning, and environmental history. Information on topographical setting and morphometry of the rampart was gathered by an octocopter equipped with a high-resolution range finder camera. We achieved a high-resolution DEM that allowed us to map the rampart in detail and this served as a base map for all other investigations. SQUID magnetometry, ground-penetrating radar, and electric resistivity measurements (capacitive coupled geoelectrics) were subsequently used to detect archaeological remains and to characterize the sediment distribution of the inner part of the enclosure and the ramparts themselves. The data show that the construction of the walls is similar to well-known Uighur neighbouring sites. Man-made sub-surface structures or bigger finds could not be detected. Sediment cores were drilled in a nearby meander, covering 3000years BP. The analysis of the strata in terms of elemental composition (P, N, Mn, Fe, etc) revealed an increase of organic content in Medieval times, whereas the allochthonous filling of the back water must have started around the beginning of the 6th century AD. Using geophysical, archaeological and geological observations, we assume a dating in the Turk/Uighur period (6th9th century AD) and a re-use under Mongolian reign (12th17th century AD). This would mean that this site is the furthermost walled structure in the peri-urban area of Khar Balgas. However, the specific usage of this walled enclosure remains unclear and needs further analysis. © 2012 Sinopec Geophysical Research Institute.

Tobisch T.,TransMIT GmbH | Ohlmeyer H.,Mittelhessen University of Applied Sciences | Ohlmeyer H.,TransMIT GmbH | Zimmermann H.,CryLaS GmbH | And 6 more authors.
Progress in Biomedical Optics and Imaging - Proceedings of SPIE | Year: 2014

Improved multimode UV-fibers with core diameters ranging from 70 to 600 μm diameter have been manufactured based on novel preform modifications and fiber processing techniques. Only E'-centers at 214 nm and NBOHC at 260 nm are generated in these fibers. A new generation of inexpensive laser-systems have entered the market and generated a multitude of new and attractive applications in the bio-life science, chemical and material processing field. However, for example pulsed 355 nm Nd:YAG lasers generate significant UV-damages in commercially available fibers. For lower wavelengths, no results on suitable multi-mode or low-mode fibers with high UV resistance at 266 nm wavelength (pulsed 4th harmonic Nd:YAG laser) have been published. In this report, double-clad fibers with 70 μm or 100 μm core diameter and a large claddingto- core ratio will be recommended. Laser-induced UV-damages will be compared between these new fiber type and traditional UV fibers with similar core sizes. Finally, experimental results will be cross compared against broadband cw deuterium lamp damage standards. © 2014 SPIE.

Gleichmann N.,IPHT Jena | Malsch D.,IPHT Jena | Horbert P.,IPHT Jena | Henkel T.,IPHT Jena
Microfluidics and Nanofluidics | Year: 2015

Miniaturization of biological and chemical assays in lab-on-a-chip systems is a highly topical field of research. The pressure-driven droplet-based microfluidic platform is a promising way to realize these miniaturized systems by expanding the capability of assays with special features that are unreached by traditional workflows. Full custom centric design of droplet-based microfluidic lab-on-a-chip systems leads to a high system integration level and design complexity. In our work, we report on a software toolkit based on the Kirchhoff laws for modeling droplet traffic and processing for even complex microfluidic networks. Experimental validation of the simulation results was performed utilizing directional droplet transport switching in a circular channel element. This structure can be employed as a benchmark system for the experimental validation of the obtained simulation results. As a result of these experiments, our design and simulation toolkit meet the requirements for a versatile and low-risk development of custom lab-on-a-chip devices. Together with our conceptual model of microfluidic networks, most of the development problems arising with complex lab-on-a-chip applications can be solved. Due to the high computational speed, the algorithm allows an interactive in silico evaluation of even complex sample-processing workflows in droplet-based microfluidic devices prior any preparation of prototypes. Summarizing the developed toolkit may become the foundation for the future development of software tools for a microfluidic design automation. As a result of this new way of simulation-based application-driven development, the advantages of lab-on-a-chip will be accessible for more people through the easy, versatile and efficient transformation from complex laboratory workflows to compact and easy to use lab-on-a-chip applications. © 2014, Springer-Verlag Berlin Heidelberg.

Schneider M.,IPHT Jena | Stolz R.,IPHT Jena | Linzen S.,IPHT Jena | Schiffler M.,IGW | And 4 more authors.
Journal of Applied Geophysics | Year: 2013

The fast and sensitive SQUID (Superconducting Quantum Interference Device) system, which was developed at IPHT Jena, allows the geo-magnetic prospection of large land areas. The system's simultaneous high-resolution recording of all components of the Earth's magnetic field gradient tensor represents a high-quality data base for precise inversion calculations. Thus, we developed a software tool for the fast and direct inversion of full-tensor data from especially dipole-like sources. Our motivation is to localize buried magnetic objects and inhomogeneities in the underground only by measuring the gradient components at the surface. The application of the algorithm will be shown by two examples, first on a synthetic data set and second on a real data set measured at the IPHT test site with well-defined buried targets. © 2013 Elsevier B.V.

McCord J.,Helmholtz Center Dresden | Strache T.,Helmholtz Center Dresden | Monch I.,Leibniz Institute for Solid State and Materials Research | Mattheis R.,IPHT Jena | Fassbender J.,Helmholtz Center Dresden
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

The spatial manipulation of the effective magnetic damping parameter in ferromagnetic-antiferromagnetic-ferromagnetic film systems is shown. By applying ultrathin antiferromagnetic layers in Ni81Fe19/IrMn/ Ni81Fe19 sandwich structures in combination with low fluence Ni-ion irradiation, a lateral control of the effective magnetic damping parameter is achieved. With irradiation, an interfacial intermixing and roughening is introduced, by which the interfacial coupling mechanisms and the magnetic state of the interlayer are altered. We find an exponential decay of all relevant magnetic property parameters with irradiation. Local irradiation is then applied to generate a magnetic layer with spatially distributed regions of different values of damping. The resulting overall relaxation time of the mixed property film is a direct superposition of the individual relaxation contributions. Thereby, the ratio of the phases with individual damping parameter determines the resulting overall damping. © 2011 American Physical Society.

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