@article{LuxEdlingLuccietal.2019, author = {Lux, Helge and Edling, Matthias and Lucci, Massimiliano and Kitzmann, Julia and Villringer, Claus and Siemroth, Peter and De Matteis, Fabio and Schrader, Sigurd}, title = {The Role of Substrate Temperature and Magnetic Filtering for DLC by Cathodic Arc Evaporation}, series = {Coatings}, volume = {9}, journal = {Coatings}, number = {5}, issn = {2079-6412}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-12295}, pages = {345}, year = {2019}, abstract = {Diamond-like carbon (DLC) films were deposited using two different types of high current arc evaporation. The first process used a magnetic particle filter to remove droplets from the plasma. For the second process, the samples were put into a metallic cage which was placed directly above the plasma source. For both processes, we varied the substrate temperature from 21 to 350 °C in order to investigate the temperature effect. The samples were characterized using SEM, AFM, XPS, Raman Spectroscopy, Ellipsometry, Photometry, and Nano Indentation in order to compare both methods of deposition and provide a careful characterization of such DLC films. We found that the sp3 content and the hardness can be precisely adjusted by changing the substrate temperature. Furthermore, in the case of unfiltered deposition, the optical constants can be shifted in the direction of higher absorbance in order to produce black and hard carbon coatings.}, language = {en} } @article{SteglichVillringerDietzeletal.2019, author = {Steglich, Patrick and Villringer, Claus and Dietzel, Birgit and Mai, Christian and Schrader, Sigurd and Casalboni, Mauro and Mai, Andreas}, title = {On-Chip Dispersion Measurement of the Quadratic Electro-Optic Effect in Nonlinear Optical Polymers Using a Photonic Integrated Circuit Technology}, series = {IEEE Photonics Journal}, volume = {11}, journal = {IEEE Photonics Journal}, number = {3}, issn = {1943-0655}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-12307}, year = {2019}, abstract = {A novel method to determine the dispersion of the quadratic electro-optic effect in nonlinear optical materials by using a silicon-on-insulator microring resonator is presented. The microring consists of a silicon slot waveguide enabling large dc electric field strength at low applied voltages. The dispersion of third-order hyperpolarizability of a linear conjugated dye is approximated by using a two-level model for the off-resonant spectral region. As an example, the dispersion of the resonance wavelength of the resonator filled with a dye doped polymer was measured in dependence of the applied dc voltage. The polymer was poly (methylmethacrylate) doped with 5 wt\% disperse red 1 (DR1), and the measurements have been carried out at the telecommunication wavelength band around 1550 nm (optical C-band). The described measurements represent a new technique to determine the dispersion of the third-order susceptibility and molecular hyperpolarizability of the material filled into the slot of the ring-resonator.}, language = {en} } @article{LuxEdlingSiemrothetal.2018, author = {Lux, Helge and Edling, Matthias and Siemroth, Peter and Schrader, Sigurd}, title = {Fast and Cost-Effective Synthesis of High-Quality Graphene on Copper Foils Using High-Current Arc Evaporation}, series = {Materials}, volume = {11}, journal = {Materials}, number = {5}, issn = {1996-1944}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-10359}, pages = {1 -- 10}, year = {2018}, abstract = {In this paper, we present an innovative and ultra-fast process for the deposition of high-quality graphene on different metal foils and thin metal films. The graphene layer can be homogeneously deposited in only 30 s process time. Due to the weak adhesion to the substrate material, the monolayer graphene is easy to transfer using the established processes. For the production, we use magnetic filtered high-current arc evaporation (Φ-HCA) with a solid, graphitic carbon source. This ultra-fast growth process can pave the way towards a cost-effective graphene synthesis for the mass production e.g., in a roll-to-roll process, avoiding time consuming established processes.}, language = {en} } @article{GrytsenkoKsianzouKolomzarovetal.2021, author = {Grytsenko, Kostyantyn and Ksianzou, Viachaslau and Kolomzarov, Yurii and Lytvyn, Peter and Dietzel, Birgit and Schrader, Sigurd}, title = {Fluoropolymer Film Formation by Electron Activated Vacuum Deposition}, series = {Surfaces}, volume = {4}, journal = {Surfaces}, number = {1}, publisher = {MDPI}, issn = {2571-9637}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-13786}, pages = {66 -- 80}, year = {2021}, abstract = {Polytetrafluoroethylene (PTFE), polyhexafluoropropylene (PHFP) and polychlorotrifluoroethylene (PCTFE) were heated to their decomposition temperature in a high vacuum. The emitted fragments passed an electron cloud, condensed on a substrate and formed fluoropolymer film. Growth rate of PTFE and PHFP films increased up to a factor five in the presence of the electron cloud. Mass spectrometry revealed changes in the mass spectra of fragments generated by thermal decomposition only and formed under electron activation. The observed changes were different for each fluoropolymer. Infrared spectroscopy (IRS) showed that the structure of the films was close to the structure of the bulk polymers. Atomic force microscopy (AFM) has revealed different morphologies of PTFE, PHFP and PCTFE films, suggesting a Volmer-Weber growth mechanism for PTFE and PHFP but a Frank-van der Merwe one for PCTFE. All films were smooth at nanoscale and transparent from ultraviolet to near-infrared region. Additional radio frequency (RF) plasma ignited in the emitted fragments at a low pressure increased mechanical characteristics of the films without losing their optical transparency and smoothness.}, language = {en} } @misc{BeyerHofmannTrutzetal.2013, author = {Beyer, Harald and Hofmann, Mandy and Trutz, Sebastian and Lux, Helge and Stissel, Sven and Mehr, Wolfgang and Schrader, Sigurd and Siemroth, Peter}, title = {Großfl{\"a}chige Abscheidung von Graphen - Ein wichtiger Schritt f{\"u}r neuartige Bauelemente}, series = {Wissenschaftliche Beitr{\"a}ge 2013}, volume = {17}, journal = {Wissenschaftliche Beitr{\"a}ge 2013}, issn = {0949-8214}, doi = {10.15771/0949-8214_2013_1_27}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-3169}, pages = {154 -- 159}, year = {2013}, abstract = {Das wachsende Interesse an Graphen beruht auf seiner unverwechselbaren Bandstruktur und seinen damit zusammenh{\"a}ngenden herausragenden physikalischen Eigenschaften. Es wird daher weltweit nach einem Verfahren gesucht, Graphen großfl{\"a}chig und mit hoher Qualit{\"a}t abzuscheiden. In einer an der TH Wildau [FH] speziell f{\"u}r diese Aufgabe konzipierten Reaktionskammer wurde die Herstellung mittels chemischer Gasphasenabscheidung auf katalytischen Metalloberfl{\"a}chen f{\"u}r verschiedene Parameter studiert und deren Vertr{\"a}glichkeit mit der CMOS -Technologie untersucht. Die ersten Tests erfolgten auf Nickel, da hier eine im Volumen stattfindende katalytische Reaktion einsetzt. In weiteren Schritten fiel die Wahl auf Kupfer, da hier die Reaktion an der Oberfl{\"a}che stattfindet und daher ein stabilerer Prozess realisiert werden konnte. Die Qualit{\"a}tspr{\"u}fung der erzeugten Schichten erfolgte mittels Ramanspektrometrie.}, language = {de} } @article{DimitrievGrytsenkoTolmachevetal.2014, author = {Dimitriev, O. P. and Grytsenko, Kostyantyn and Tolmachev, O. I. and Slominskii, Yu L. and Kudinova, M. A. and Schrader, Sigurd}, title = {Effect of Concentration on Isomerization of Rhodanine Derivatives of Merocyanine Dyes in Polar Solvents}, series = {Advances in Physical Chemistry}, volume = {2014}, journal = {Advances in Physical Chemistry}, issn = {1687-7993}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-5931}, pages = {9}, year = {2014}, abstract = {Rhodanine derivatives of merocyanine dyes with residues of 1,3,3-trimethyl-3H-indole and 3-ethylbenzothiazoline have been found to possess two molecular forms in diluted solutions of polar solvents such as dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidinone. The first molecular form was observed to prevail at low concentrations of the dyes, normally up to 10-5 M. The second one prevails at higher concentrations and is displayed through a new band in the electronic absorption spectrum, which is red-shifted with respect to the absorption band of the first form. No similar effect was found for these dyes by use of nonpolar solvents or upon alkyl-substitution of the molecules at nitrogen atom in the rhodanine moiety. We assign the above two forms to different molecular isomers and the analogous spectral changes were shown to take place by light or heat influence which correspond to a typical isomerization effect for the related merocyanine dyes. It is discussed that the isomer transformation is facilitated by the increased mobility of the proton bonded to the nitrogen atom of the rhodanine moiety in the polar environment and the increased amount of dye-dye collisions.}, language = {en} } @inproceedings{SteglichVillringerDuemeckeetal.2015, author = {Steglich, Patrick and Villringer, Claus and D{\"u}mecke, Silvio and Padilla-Michel, Yazmin and Casalboni, Mauro and Schrader, Sigurd}, title = {Silicon-On-Insulator Slot-Waveguide Design Trade-Offs}, series = {Proceedings of the 3rd International Conference on Photonics, Optics and Laser Technology : vol. 2}, booktitle = {Proceedings of the 3rd International Conference on Photonics, Optics and Laser Technology : vol. 2}, publisher = {SciTePress}, address = {Set{\´u}bal}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-20104}, pages = {47 -- 52}, year = {2015}, abstract = {Silicon-on-insulator slot-waveguide structures are designed and analysed numerically. We present our theoretical investigation of field confinement factors and effective nonlinear areas for different waveguide structures in order to find optimized geometrical dimensions. It is shown that a slot-waveguide with a height of 220 nm, a slot width of 180 nm and a silicon rail width of 180 nm provides a five times higher field confinement in the cladding region compared to conventional strip-waveguides which explains the high sensitivity of slotwaveguide based label-free bio-sensors.}, language = {en} } @inproceedings{PadillaMichelLucciCasalbonietal.2015, author = {Padilla-Michel, Yazmin and Lucci, Massimiliano and Casalboni, Mauro and Steglich, Patrick and Schrader, Sigurd}, title = {Mechanical Characterisation of the Four Most Used Coating Materials for Optical Fibres}, series = {Proceedings of the 3rd International Conference on Photonics, Optics and Laser Technology : vol. 1}, booktitle = {Proceedings of the 3rd International Conference on Photonics, Optics and Laser Technology : vol. 1}, editor = {Ribeiro, Paulo A.}, publisher = {SciTePress}, address = {Set{\´u}bal}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-20063}, pages = {96 -- 102}, year = {2015}, abstract = {Optical multimode fibres have a wide variety of applications ranging from industrial to medical use. Therefore, even if they are just used as waveguides or sensors, it is important to characterise the whole fingerprint, including the optical and mechanical properties of such fibres. Since the stiffness/elasticity of a material could influence the optical output of a fibre due to micro-bendings, in this paper we report the calculated Young's Modulus of acrylate, fluorinated acrylate, polyimide and silicone, which are the four most used coating materials for such optical components. The results demonstrate that Young's Modulus does have an impact on the attenuation of propagating light along the optical fibre. However, the refractive index of the coating materials still has a significant impact on the performance of optical fibres.}, language = {en} } @article{GrytsenkoLozovskiStrilchuketal.2012, author = {Grytsenko, Kostyantyn and Lozovski, Valeri and Strilchuk, Galyna and Schrader, Sigurd}, title = {Evaluation of the Mechanism of the Gold Cluster Growth during Heating of the Composite Gold-Polytetrafluoroethylene Thin Film}, series = {Nanomaterials}, volume = {2}, journal = {Nanomaterials}, number = {4}, issn = {2079-4991}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-6387}, pages = {366 -- 378}, year = {2012}, abstract = {Nanocomposite films consisting of gold inclusions in the polytetrafluoroethylene (PTFE) matrix were obtained by thermal vacuum deposition. Annealing of the obtained films with different temperatures was used to measure varying of film morphologies. The dependence of optical properties of the films on their morphology was studied. It was established that absorption and profile of the nanocomposite film obtained by thermal vacuum deposition can be changed with annealing owing to the fact that different annealing temperatures lead to different average particle sizes. A method to calculate the optical properties of nanocomposite thin films with inclusions of different sizes was proposed. Thus, comparison of experimental optical spectra with the spectra obtained during the simulation enables estimating average sizes of inclusions. The calculations give the possibility of understanding morphological changes in the structures.}, language = {en} } @article{VillringerSteglichPulweretal.2021, author = {Villringer, Claus and Steglich, Patrick and Pulwer, Silvio and Schrader, Sigurd and Laufer, Jan}, title = {Electro-optical properties of doped polymers with high transparency in the visible wavelength range}, series = {Optical Materials Express}, volume = {11}, journal = {Optical Materials Express}, number = {11}, publisher = {Optica Publishing Group}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-15480}, pages = {3801 -- 3811}, year = {2021}, abstract = {The electro-optical (EO) properties of poly(methyl methacrylate) and the photopolymer poly(vinyl cinnamate) doped with varying concentrations of the EO chromophore 2-Methyl-4-nitroaniline were measured. The EO polymers were embedded in Fabry-P{\´e}rot etalons for the simultaneous determination of the Pockels and Kerr coefficients from measurements of the fringe shift induced by an external electric field. It was found that the host polymer has a significant impact on the EO performance and that the undoped host polymers exhibit a significant Pockels effect. Moreover, the Kerr effect provides a substantial contribution of 27\% to the total change of the refractive index at relatively high electric field strengths of E = 91.2 MV m-1.}, language = {en} } @article{BauerFursenkoHeinrichetal.2022, author = {Bauer, Joachim and Fursenko, Oksana and Heinrich, Friedhelm and Gutke, Marko and Kornejew, Eckhart and Br{\"o}del, Oliver and Dietzel, Birgit and Kaltenbach, Alexander and Burkhardt, Martin and Edling, Matthias and Steglich, Patrick and Herzog, Michael and Schrader, Sigurd}, title = {Determination of optical constants and scattering properties of transparent polymers for use in optoelectronics}, series = {Optical Materials Express}, volume = {12}, journal = {Optical Materials Express}, number = {1}, publisher = {Optica Publishing Group}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-15666}, pages = {204 -- 224}, year = {2022}, abstract = {Knowledge of optical constants, i.e. refractive index n and extinction coefficient k, and light scattering properties of optical polymers are required to optimize micro-optics for light-emitting diodes in terms of efficiency, color properties and light distribution. We present here a model-based diagnostic approach to determine the optical properties of polymers, which should be particularly useful in the development of plastics for optical applications. Optical constants and scattering coefficients were obtained from transmission and reflection measurements in a wavelength range from UV to NIR taking into account scattering effects due to rough surfaces and volume inhomogeneity. Based on the models for the dielectric function, the molecular optical transition energies Eg, critical point energies, Urbach energies and exciton transition energies were determined. Rayleigh and Mie scattering model and van de Hulst\&\#x0027;s anomalous diffraction theory were applied to characterize scattering due to volume inhomogeneities. Scalar diffraction theory was applied to account for surface roughness scattering. Atomic force microscopy with nanomechanical characterization was used to characterize domains in size and shape and to assign optical scattering to a suitable morphological model. The combined optical and mechanical characterization help to improve the qualification of new polymer materials for optical applications.}, language = {en} }