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Göttingen, Germany

Chizhik A.I.,University of Gottingen | Gregor I.,University of Gottingen | Schleifenbaum F.,University of Tubingen | Muller C.B.,University of Gottingen | And 3 more authors.
Physical Review Letters | Year: 2012

We investigate the impact of rotational diffusion on the electrodynamic coupling of fluorescent dye molecules (oscillating electric dipoles) to a tunable planar metallic nanocavity. Fast rotational diffusion of the molecules leads to a rapidly fluctuating mode density of the electromagnetic field along the molecules' dipole axis, which significantly changes their coupling to the field as compared to the opposite limit of fixed dipole orientation. We derive a theoretical treatment of the problem and present experimental results for rhodamine 6G molecules in cavities filled with low and high viscosity liquids. The derived theory and presented experimental method is a powerful tool for determining absolute quantum yield values of fluorescence. © 2012 American Physical Society.


Wurstbauer U.,University of Regensburg | Wurstbauer U.,Columbia University | Roling C.,Accurion GmbH | Wegscheider W.,University of Regensburg | And 5 more authors.
Applied Physics Letters | Year: 2010

Imaging ellipsometry studies of graphene on SiO2 /Si and crystalline GaAs are presented. We demonstrate that imaging ellipsometry is a powerful tool to detect and characterize graphene on any flat substrate. Variable angle spectroscopic ellipsometry is used to explore the dispersion of the optical constants of graphene in the visible range with high lateral resolution. In this way, the influence of the substrate on graphene's optical properties can be investigated. © 2010 American Institute of Physics.


Utke I.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Jenke M.G.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Roling C.,Accurion GmbH | Thiesen P.H.,Accurion GmbH | And 5 more authors.
Nanoscale | Year: 2011

Local electron triggered reactions of functional surface adsorbates were used as a maskless, dry, and minimally invasive nanolithography concept to stabilize the polarisation of individual vertical cavity surface emitting lasers (VCSELs) on a wafer in a post-processing step. Using a 30 keV focused electron beam of a scanning electron microscope and injecting volatile organo-metallic (CH3)2Au(tfa) molecules, polarisation gratings were directly written on VCSELs by dissociating the surface adsorbed molecules. The electron triggered adsorbate dissociation resulted in electrically conductive Au-C nano-composite material, with gold nanocrystals embedded in a carbonaceous matrix. A resistivity of 2500 cm was measured at a typical composition of 30 at.% Au. This material proved successful in suppressing polarisation switching when deposited as line gratings with a width of 200 nm, a thickness of 50 nm, and a pitch of 500 nm and 1m. Refractive index measurements suggest that the optical attenuation by the deposited Au-C material is much lower than by pure Au thus giving a low emission power penalty while keeping the polarisation stable. © 2011 The Royal Society of Chemistry.


Roling C.,Accurion GmbH | Thiesen P.,Accurion GmbH | Meshalkin A.,Moldova Academy of Sciences | Achimova E.,Moldova Academy of Sciences | And 3 more authors.
Journal of Non-Crystalline Solids | Year: 2013

Photoinduced diffraction grating formation in amorphous As 2S3 thin films has been studied using imaging ellipsometry. We first have applied the ACCURION Nanofilm-EP3SE Imaging Spectroscopic Ellipsometer to obtain mapping of diffraction gratings in amorphous As2S3 thin films based on different photoinduced phenomena, namely photodarkening and photoinduced changes of refractive index. The profile and absolute value of refractive index in gratings were studied as a function of exposure. It is shown that underexposure led to the formation of a sinusoidal profile of the refractive index. The proper exposure produced results close to the cycloidal profile. Overexposure led to the same cycloidal profile but with reduced amplitude of refractive index variation in comparison with that obtained under proper exposure. © 2013 Elsevier B.V.


Utke I.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Jenke M.G.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Roling C.,Accurion GmbH | Thiesen P.H.,Accurion GmbH | And 5 more authors.
Technical Proceedings of the 2011 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2011 | Year: 2011

Gas assisted focused electron beam induced deposition was used as a maskless, dry, and minimally invasive nanofabrication concept to stabilize the polarisation of individual vertical cavity surface emitting lasers (VCSELs) on a wafer in a single post-processing step [1]. Using a 30 keV focused electron beam of a scanning electron microscope and injecting volatile dimethyl-gold-trifluoroacetylacetonate molecules, polarization grids were directly written on VCSELs by dissociating the surface adsorbed molecules. The electron triggered adsorbate dissociation resulted in electrically conductive Au-C nanocomposite material with gold nanocrystals embedded in a carbonaceous matrix. This material proved successful in suppressing polarization switching when deposited as line grids with a width of 200 nm, a thickness of 50 nm, and a pitch of 500 nm and 1 μm.

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