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Paetzold U.W.,Forschungszentrum Juelich GmbH | Moulin E.,Forschungszentrum Juelich GmbH | Michaelis D.,Fraunhofer Institute For Angewandte Optik Und Feinmechanik | Bottler W.,Forschungszentrum Juelich GmbH | And 5 more authors.
Applied Physics Letters | Year: 2011

We report on the fabrication and optical simulation of a plasmonic light-trapping concept for microcrystalline silicon solar cells, consisting of silver nanostructures arranged in square lattice at the ZnO:Al/Ag back contact of the solar cell. Those solar cells deposited on this plasmonic reflection grating back contact showed an enhanced spectral response in the wavelengths range from 500 nm to 1000 nm, when comparing to flat solar cells. For a particular period, even an enhancement of the short circuit current density in comparison to the conventional random texture light-trapping concept is obtained. Full three-dimensional electromagnetic simulations are used to explain the working principle of the plasmonic light-trapping concept. © 2011 American Institute of Physics. Source

Weber T.,Friedrich - Schiller University of Jena | Kasebier T.,Friedrich - Schiller University of Jena | Kley E.-B.,Friedrich - Schiller University of Jena | Tunnermann A.,Friedrich - Schiller University of Jena | Tunnermann A.,Fraunhofer Institute For Angewandte Optik Und Feinmechanik
Optics Letters | Year: 2011

In this Letter, we present an iridium wire grid polarizer with a large spectral working range from IR down to the UV spectral region. The required grating period of 100 nm for an application below a wavelength of 300 nm was realized using a spatial frequency doubling technique based on ultrafast electron beam writing. The optical performance of the polarizer at a wavelength of 300 nm is a transmittance of almost 60% and an extinction ratio of about 30 (15 dB). Furthermore, the oxidation resistance is discussed. © 2011 Optical Society of America. Source

Schulze M.,Friedrich - Schiller University of Jena | Lehr D.,Friedrich - Schiller University of Jena | Lehr D.,Carl Zeiss GmbH | Helgert M.,Carl Zeiss GmbH | And 3 more authors.
Optics Letters | Year: 2011

We present transmission increased fused silica lenses produced by using self-organized antireflective structures for which we developed an efficient manufacturing process. The spectral transmission measured over the whole lens aperture shows a significant transmission enhancement of up to 3.5% in the UV range. Local measurements on the lens's surface reveal a strongly reduced reflection of below 0.1% for 300nm wavelength, which is homogeneous over the whole lens. Further, the lenses show a broadband spectral antireflection behavior. For 600nm wavelength the reflection was measured at about 1%. © 2011 Optical Society of America. Source

Kohler S.,University of Leipzig | Benz C.,University of Leipzig | Becker H.,Microfluidic ChipShop GmbH | Beckert E.,Fraunhofer Institute For Angewandte Optik Und Feinmechanik | And 2 more authors.
RSC Advances | Year: 2012

In this work we present an approach towards economic free-flow electrophoresis chips fabricated by injection molding as mass replication process. This is achieved by the development of a free-flow electrophoresis chip design suitable for one step molding fabrication. Integrated partitioning bars are incorporated as key elements for bubble segregation. A defined open gap of 20 μm in height and 500 μm in width was integrated between the separation chamber and the electrode channels, acting as a barrier for gas bubbles while maintaining electrical contact by the fluidic junction. Additionally, we present an approach to avoid internal electrodes in FFE microchips for a facile mass production process. The injection molded thermoplastic μFFE chips are ready to use without subsequent labor-intensive implementation of membranes or comparable structures serving as salt bridges. © 2012 The Royal Society of Chemistry. Source

Hellwig T.,University of Munster | Schnack M.,University of Munster | Walbaum T.,University of Munster | Walbaum T.,Fraunhofer Institute For Angewandte Optik Und Feinmechanik | And 2 more authors.
Optics Express | Year: 2014

We present the experimental realization of transverse mode conversion in an optical fiber via an optically induced long-period grating. The transient gratings are generated by femtosecond laser pulses, exploiting the Kerr effect to translate intensity patterns emerging from multimode interference into a spatial refractive index modulation. Since these modulations exist only while the pump beam is present, they can be used for optical switching of transverse modes. As only a localized part of the grating was written at a time and the probe beam was co-propagating with the pump beam the required pulse energies could be reduced to 120 nJ which is about a factor of 600 lower than in previous quasi-continuous-wave experiments. Accompanying numerical simulations allow a better understanding of the involved effects and show excellent agreement to the experimental results. © 2014 Optical Society of America. Source

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