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The new generation of laser-based solid-state lighting (SSL) white light sources requires new material systems capable of withstanding, diffusing and converting high intensity laser light. State-of-the-art systems use a blue light emitting diode (LED) or laser diode (LD) in combination with color conversion materials, such as yellow emitting Ce-doped phosphors or red and green emitting quantum dots (QD), to produce white light. However, for laser-based high-brightness illumination in particular, thermal management is a major challenge, and in addition, a light diffuser is required to diffuse the highly focused laser beam. Here, we present a hybrid material system that simultaneously enables efficient, uniform light distribution and color conversion of a blue LD, while ensuring good thermal management even at high laser powers of up to 5W. A highly open porous (> 99%) framework structure of hollow SiO$_2$ microtubes is utilized as an efficient light diffuser that can drastically reduce speckle contrast. By further functionalizing the microtubes with halide perovskite QDs (SiO$_2$@CsPbBr$_3$ as model system) color conversion from UV to visible light is achieved. Under laser illumination, the open porous structure prevents heat accumulation and thermal quenching of the QDs. By depositing an ultrathin (~ 5.5 nm) film of poly(ethylene glycol dimethyl acrylate) (pEGDMA) via initiated chemical vapor deposition (iCVD), the luminescent stability of the QDs against moisture is enhanced. The demonstrated hybrid material system paves the way for the design of advanced and functional laser light diffusers and converters that can meet the challenges associated with laser-based SSL applications., Corresponding authors: Fabian Sch\"utt, Huayna Terraschke

Magnetoelastic sensors for the detection of low-frequency and low-amplitude magnetic fields are in the focus of research since more than 30 years. In order to minimize the limit of detection (LOD) of such sensor systems, it is of high importance to understand and to be able to quantify the relevant noise sources. In this contribution, cantilever-type electromechanic and magnetoelastic resonators, respectively, are comprehensively investigated and mathematically described not only with regard to their phase sensitivity but especially to the extent of the sensor-intrinsic phase noise. Both measurements and calculations reveal that the fundamental LOD is limited by additive phase noise due to thermal-mechanical noise of the resonator, i.e. by thermally induced random vibrations of the cantilever, and by thermal-electrical noise of the piezoelectric material. However, due to losses in the magnetic material parametric flicker phase noise arises, limiting the overall performance. In particular it is shown that the LOD is virtually independent of the magnetic sensitivity but is solely determined by the magnetic losses. Instead of the sensitivity, the magnetic losses, represented by the material's effective complex permeability, should be considered as the most important parameter for the further improvement of such sensors in the future. This implication is not only valid for magnetoelastic cantilevers but also applies to any type of magnetoelastic resonator.

Oral presentation given at the DGP Verhandlungen, held in Berlin (Germany) on March 15-20th, 2015., The reproducible low-cost fabrication of functional polymer-metal-nanocomposites with tailored optoelectronic properties remains a major issue in applied nanotechnology. In order to obtain full control over the nanostructural evolution at the metal-polymer interface and its impact on optoelectronic properties, we employed the combination of in-situ time-resolved GISAXS [1] with in-situ surface differential reflectivity spectrometry during sputter deposition of gold on thin polystyrene films. We correlate the evolution of the metallic layer morphology with changes in the key scattering. This enabled us to identify the different growth regimes with their specific thresholds and permits a better understanding of the growth kinetics of gold clusters on polymer substrates. Our study opens up the opportunity to improve nanofabrication of tailored metal-polymer nanostructures for organic electronics like photovoltaic applications and plasmonic-based technologies.

Poster presented at the DGP Verhandlungen, held in Berlin (Germany) on March 15-20th, 2015., Although it is well established in industry and important for many applications the sputter deposition of metals onto organic surfaces is yet to be completely understood. Due to the inherent complexity (e.g. bombardment of the organic surfaces by energetic ions) of the sputtering process the basic mechanisms determining the final microstructure are still to be identified. The complexity of sputter deposition and the post-deposition changes which are to be expected necessitate the use of in-situ methods. In-situ grazing incidence small angle scattering (GISAXS) has been used to extract structural information with high spatial and temporal resolution from a growing Au-film deposited via RF-sputter deposition onto a P(VDF-TrFE)-film. The Au-P(VDF-TrFE) system has been chosen as a model system of a relatively inert metal-polymer pair. Analysis of the GISAXS data yields information about the morphology of the growing Au-film. Comparing these results to simulated scattering data provides further information about the basic growth mechanisms acting at different stages of the growth of the metal film.

An optically driven metamaterial with a photoswitchable weak and strong molecular‐plasmonic coupling is demonstrated. In this active perfect absorber, the absorption band can be broadened more than 150 nm (split with an energy difference of 780 meV) by UV irradiation, which demonstrates a new class of optically tunable metamaterial absorber for visible frequencies.

Mc 2009. Microscopy Conference, Graz, Austria. 30 August - 4 September 2009. First Joint Meeting Of Dreiländertagung And Multinational Congress On Microscopy.