@inproceedings{GrytsenkoDoroshenkoKolomzarovetal.2008, author = {Grytsenko, Kostyantyn and Doroshenko, T. and Kolomzarov, Yurii and Prokopets, Vadym M. and Fedoriak, O. and Zelinski, R. and Lytvyn, Oksana and Prescher, Dietrich and Grimm, Bernd and Ksianzou, Viachaslau and Schrader, Sigurd and Tolmachev, O. I. and Slominskii, Yu L. and Kurdiukov, V. and Smirnova, G.}, title = {Research on the growth of dye film in vacuum in situ}, publisher = {Society of Photo-Optical Instrumentation Engineers (SPIE)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-15206}, pages = {318 -- 323}, year = {2008}, abstract = {Organic film deposition in vacuum is fast developing scientific and industrial domain. We developed installation for deposition of organic films equipped with optical spectrometer for measurements in situ. We are developing new dyes aimed for application in waveguide sensor, nonlinear optics and studying film organisation during deposition. Fluorinated azo-dyes and azomethine dyes were synthesized at University of Applied Sciences Wildau and at the Institute of Organic Chemistry, Kyiv. Compounds were evaporated at a pressure of 10-3 Pa using resistive heated crucible. Glass and glass covered with polytetrafluoroethylene (PTFE) film are used as substrates. The films were studied with Polytec and StellarNet spectrometers and an atomic force microscope. Optical spectra of the dye films revealed, that some compounds were decomposed during evaporation. Several kinds of dyes were evaporated and deposited without decomposition. Some deposited films formed H-aggregates and other types of aggregates. AFM images of dye films showed that their morphology depends on the chemical structure of the compounds and on the nature of the substrate on which the film was grown.}, language = {en} } @inproceedings{BauerHeinrichFursenkoetal.2017, author = {Bauer, Joachim and Heinrich, Friedhelm and Fursenko, Oksana and Marschmeyer, Steffen and Bluemich, Adrian and Pulwer, Silvio and Steglich, Patrick and Villringer, Claus and Mai, Andreas and Schrader, Sigurd}, title = {Very high aspect ratio through silicon via reflectometry}, series = {Proceedings of SPIE}, booktitle = {Proceedings of SPIE}, issn = {1996-756X}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-13758}, year = {2017}, abstract = {Through Silicon Via (TSV) technology is a key feature of new 3D integration of circuits by creation of interconnections using vias, which go through the silicon wafer. Typically, the highly-selective Bosch Si etch process, characterized by a high etch rate and high aspect ratio and forming of scallops on the sidewalls is used. As presented in this paper, we have developed an experimental setup and a respective evaluation algorithm for the control and monitoring of very high aspect ratio TSV profiles by spectroscopic reflectometry. For this purpose square via arrays with lateral dimension from 3 to 10 μm were fabricated by a Bosch etch process and analyzed by our setup. By exploiting interference and diffraction effects of waves reflected from the top and bottom surfaces as well as from the side walls of the TSV patterns, the measurements provided etch depths, CD values and scallop periods. The results were compared with data obtained by a commercial wafer metrology tool. Aspect ratios of up to 35:1 were safely evaluable by our setup.}, language = {en} } @article{GrytsenkoSchraderDetert2014, author = {Grytsenko, Kostyantyn and Schrader, Sigurd and Detert, Heiner}, title = {Ultra-stable dye-filled polytetrafluoroethylene thin films}, series = {Nanoscience \& Technology: Open Access}, volume = {1}, journal = {Nanoscience \& Technology: Open Access}, number = {2}, issn = {2374-8141}, doi = {10.15771/2374-8141_2014_1}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-5947}, pages = {5}, year = {2014}, abstract = {Polytetrafluoroethylene (PTFE) and polyparaphenylene sulphide (PPS) thin films filled with molecules of different dyes were obtained by co-deposition in vacuum. The PTFE matrix prevented aggregation of dye molecules more strongly, than PPS matrix. During heating PTFE matrix kept the dye molecules in not aggregated state up to dye decomposition temperature. Dyes of all types, buried in the PTFE matrix, exhibited high stability toward actions of external factors: light, temperature, acids.}, language = {en} } @article{BauerGutkeHeinrichetal.2020, author = {Bauer, Joachim and Gutke, Marko and Heinrich, Friedhelm and Edling, Matthias and Stoycheva, Vesela and Kaltenbach, Alexander and Burkhardt, Martin and Gruenefeld, Martin and Gamp, Matthias and Gerhard, Christoph and Steglich, Patrick and Steffen, Sebastian and Herzog, Michael and Dreyer, Christian and Schrader, Sigurd}, title = {Novel UV-transparent 2-component polyurethane resin for chip-on-board LED micro lenses}, series = {Optical Materials Express}, volume = {10}, journal = {Optical Materials Express}, number = {9}, issn = {2159-3930}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-13472}, pages = {2085 -- 2099}, year = {2020}, abstract = {In this work we present a novel optical polymer system based on polyurethane elastomer components, which combines excellent UV transparency with high thermal stability, good hardness, high surface tension and long pot life. The material looks very promising for encapsulation and microlensing applications for chip-on-board (CoB) light-emitting diodes (LED). The extinction coefficient k, refractive index n, and bandgap parameters were derived from transmission and reflection measurements in a wavelength range of 200-890 nm. Thermogravimetry and differential scanning calorimetry were used to provide glass transition and degradation temperatures. The surface tension was determined by means of contact angle measurements. As proof of concept, a commercial InGaN-CoB-LED is used to demonstrate the suitability of the new material for the production of microlenses.}, language = {en} } @inproceedings{PrelipceanuCojocariuGrauretal.2015, author = {Prelipceanu, Marius and Cojocariu, Lucian and Graur, Adrian and Schrader, Sigurd}, title = {Analysis of thermally stimulated processes in new phenanthroline derivatives suitable for optoelectronic devices}, series = {Journal of Physics: Conference Series (JPCONF)}, volume = {585}, booktitle = {Journal of Physics: Conference Series (JPCONF)}, issn = {1742-6596}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-12050}, year = {2015}, abstract = {Thermally stimulated processes have been studied in thin films of phenanthroline derives to describe the states that had been localized. Ultraviolet Photoelectron Spectroscopy had checked out before thin films of new pyrrolo[l,2-a][l,10] phenanthroline derivatives [1], in order to further applications in optoelectronic devices. The investigated compounds have an electronic band structure which is due to the substituent (R=NO2, Cl) induced transformations of molecular orbitals. Thermally stimulated discharge currents (TSDC) attested dipolar and charge transport mechanisms. Each TSDC peak has been assigned to elementary processes that are different utilizing in addition dielectric spectroscopy (DES), and the mean trap depths have been approximated from thermally stimulated luminescence (TSL) curves.}, language = {en} } @inproceedings{MessaoudiDasLangeetal.2014, author = {Messaoudi, Hamza and Das, Susanta Kumar and Lange, Janine and Heinrich, Friedhelm and Schrader, Sigurd and Frohme, Marcus and Grunwald, R{\"u}diger}, title = {Femtosecond laser induced nanostructuring for surface enhanced Raman spectroscopy}, publisher = {Society of Photo-Optical Instrumentation Engineers (SPIE)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-15252}, pages = {61 -- 68}, year = {2014}, abstract = {The formation of periodical nanostructures with femtosecond laser pulses was used to create highly efficient substrates for surface-enhanced Raman spectroscopy (SERS). We report about the structuring of silver and copper substrates and their application to the SERS of DNA (herring sperm) and protein molecules (egg albumen). The maximum enhancement factors were found on Ag substrates processed with the second harmonic generation (SHG) of a 1-kHz Ti:sapphire laser and structure periods near the SHG wavelength. In the case of copper, however, the highest enhancement was obtained with long-period ripples induced with at fundamental wavelength. This is explained by an additional significant influence of nanoparticles on the surface. Nanostructured areas in the range of 1.25 mm2 were obtained in 10 s. The surfaces were characterized by scanning electron microscopy, Fast Fourier Transform and Raman spectroscopy. Moreover, the role of the chemical modification of the metal structures is addressed. Thin oxide layers resulting from working in atmosphere which improve the biocompatibility were indicated by vibration spectra. It is expected that the detailed study of the mechanisms of laser-induced nanostructure formation will stimulate further applications of functionalized surfaces like photocatalysis, selective chemistry and nano-biology.}, language = {en} } @misc{LangeMessaoudiDasetal.2014, author = {Lange, Janine and Messaoudi, Hamza and Das, Susanta Kumar and Grunwald, R{\"u}diger and Schrader, Sigurd and Frohme, Marcus and Heinrich, Friedhelm}, title = {Analyse komplexer biologischer Proben mittels oberfl{\"a}chenverst{\"a}rkter Ramanspektroskopie (SERS)}, series = {Wissenschaftliche Beitr{\"a}ge 2014}, volume = {18}, journal = {Wissenschaftliche Beitr{\"a}ge 2014}, issn = {0949-8214}, doi = {10.15771/0949-8214_2014_1_3}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-3300}, pages = {27 -- 32}, year = {2014}, abstract = {Diese Studie besch{\"a}ftigt sich mit dem Nachweis biologischer Proben mit Hilfe der Raman-Mikroskopie. Um ausreichende Signalintensit{\"a}ten auch bei niedrigen Konzentrationen zu erhalten, wurde insbesondere der Effekt der oberfl{\"a}chenverst{\"a}rkten Raman-Streuung (SERS) n{\"a}her untersucht. Als Proben dienten DNA aus Hering-Sperma und das Protein Albumin. Zur Verst{\"a}rkung des Raman-Spektrums wurden zwei unterschiedliche Methoden verwendet. Zum Einen wurden in einem chemischen Reduktionsprozess Nanosilberpartikel hergestellt und den biologischen Proben zugemischt. Zum Anderen wurden mit Hilfe laserangeregter periodischer Oberfl{\"a}chenstrukturierung (LIPSS) erzeugte nanostrukturierte Silberoberfl{\"a}chen als Substrate f{\"u}r die Proben verwendet. Diese Methode wurde bislang nicht f{\"u}r die SERS-Analyse biologischer Proben eingesetzt. Erste hier pr{\"a}sentierte Messungen zeigen, dass beide Verfahren signifikante SERS-Verst{\"a}rkungen liefern und potentiell leistungsstarke Methoden f{\"u}r die zerst{\"o}rungsfreie Analyse biologischer Proben darstellen.}, language = {de} } @article{MinaevJanssonAgrenetal.2006, author = {Minaev, Boris and Jansson, Emil and {\AA}gren, Hans and Schrader, Sigurd}, title = {Theoretical study of phosphorescence in dye doped light emitting diodes}, series = {The Journal of Chemical Physics}, volume = {125}, journal = {The Journal of Chemical Physics}, number = {23}, issn = {1089-7690}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-9775}, year = {2006}, abstract = {Phosphorescence of platinum(II) octaethyl porphyrin (PtOEP), which has been used in organic light emitting diodes to overcome the efficiency limit imposed by the formation of triplet excitons, is studied by time-dependent (TD) density functional theory (DFT).}, language = {en} } @misc{TudoseSchraderThiem2005, author = {Tudose, Ovidiu-Gelu and Schrader, Sigurd and Thiem, Heiko}, title = {Scanning probe investigations of morphology of new p-type material for organic field-effect transistors}, series = {Wissenschaftliche Beitr{\"a}ge 2005}, volume = {10}, journal = {Wissenschaftliche Beitr{\"a}ge 2005}, issn = {0949-8214}, doi = {10.15771/0949-8214_2005_1_13}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-4263}, pages = {70 -- 73}, year = {2005}, abstract = {Organic electronics is a fast growing field of research and technological developments. First applications based on organic electronics have been available on the market for a couple of years, so high resolution colour displays based on organic light-emitting devices are used in digital cameras or mobile phones. Efforts are still going on to find better materials and for a better understanding structure property relationships of organic semiconductors. Although exemplary applications have been realized from polymers and amorphous layers of evaporable molecular materials, crystalline organic semiconductors receive intense attention because the charge-carrier mobilities in these materials are much higher than in polymers or amorphous layers. After optimizing the electronic properties of organic devices (e.g. organic field-effect transistors or organic light emitting diodes) and demonstration of fundamental devices, attention has turned to morphology and composition of the films. Understanding and controlling the morphology of organic films will have a significant impact on the performance of organic-based devices, e.g. by minimizing the number of grain boundaries in the active region of an organic field-effect transistor (OFET).}, language = {en} } @misc{SteglichVillringerPulweretal.2016, author = {Steglich, Patrick and Villringer, Claus and Pulwer, Silvio and Bauer, Joachim and Heinrich, Friedhelm and Casalboni, Mauro and Schrader, Sigurd}, title = {Advanced Nanophotonics: Silicon-Organic Hybrid Technology}, series = {Wissenschaftliche Beitr{\"a}ge 2016}, volume = {20}, journal = {Wissenschaftliche Beitr{\"a}ge 2016}, issn = {0949-8214}, doi = {10.15771/0949-8214_2016_1_6}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-5337}, pages = {45 -- 48}, year = {2016}, abstract = {Integrated photonic devices have gained increasing research interests. Especially silicon photonics have become very attractive for various optical applications. Using silicon-on-insulator as a material platform provides the ability to fabricate photonic devices with electronic devices on a single chip. Driven by substantial research investments, the integration of photonic devices on silicon-on-insulator substrates has reached a degree of maturity that already permits industrial adoption. However, silicon has the disadvantage of linear electro-optical effects, and, therefore, advanced modulation formats are difficult to realize when using silicon-based high-speed modulators. Hence, a new approach was proposed: the silicon-organic hybrid technology. This technology is a viable extension of the silicon-on-insulator material system for efficient high-speed modulation. We herewith present our theoretical and experimental investigations of the silicon-organic hybrid slot-waveguide ring resonator. The advanced device design is described in detail, which allows using both, the efficient silicon-on-insulator strip-waveguides and the silicon-organic hybrid slot-waveguides in single ring resonator. For the first time, we report the transmission spectra of such a resonator covered with an electro-optical polymer.}, language = {en} } @inproceedings{BadoniBonaiutoCasalbonietal.2020, author = {Badoni, Davide and Bonaiuto, Vincenzo and Casalboni, Mauro and De Matteis, Fabio and Di Giuseppe, Giovanni and Frontini, Luca and Gunnella, Roberto and Liberali, Valentino and Mai, Andreas and Paoluzzi, Giovanni and Prosposito, Paolo and Salamon, Andrea and Salina, Gaetano and Sargeni, Fausto and Schrader, Sigurd and Stabile, Alberto and Steglich, Patrick}, title = {Characterization and Tests of Different Mach-Zehnder Silicon Photonic Modulator Configurations}, series = {Photonics and Photoactive Materials}, booktitle = {Photonics and Photoactive Materials}, editor = {Prosposito, Paolo}, publisher = {Materials Research Forum LLC}, address = {Millersville, PA}, isbn = {978-1-64490-071-0}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-13731}, pages = {1 -- 5}, year = {2020}, abstract = {We designed and produced an integrated silicon photonic circuit, in a single chip with IHP SG25H4_EPIC 0.25 µm technology. A Mach-Zehnder interferometer with an alternative shape for better integration, together with a standard-shape Mach-Zehnder interferometer have been realized. In this work, preliminary results of comparative performance measurements between the two Mach-Zehnder interferometer are shown.}, language = {en} } @article{LuxSiemrothSgarlataetal.2015, author = {Lux, Helge and Siemroth, Peter and Sgarlata, Anna and Prosposito, Paolo and Schubert, Markus Andreas and Casalboni, Mauro and Schrader, Sigurd}, title = {Synthesis of graphene-like transparent conductive films on dielectric substrates using a modified filtered vacuum arc system}, series = {Journal of Applied Physics}, volume = {117}, journal = {Journal of Applied Physics}, number = {19}, issn = {1089-7550}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-9738}, year = {2015}, abstract = {Here, we present a reliable process to deposit transparent conductive films on silicon oxide, quartz, and sapphire using a solid carbon source. This layer consists of partially ordered graphene flakes with a lateral dimension of about 5 nm. The process does not require any catalytic metal and exploits a high current arc evaporation (Φ-HCA) to homogeneously deposit a layer of carbon on heated substrates. A gas atmosphere consisting of Argon or Argon/Hydrogen blend acting as a buffer influences the morphology of the growing film. scanning tunneling microscopy, transmission electron microscopy, and Raman spectra were used for a thorough characterization of the samples in order to optimize the growth parameters. The best carbon layers have a surface resistance of 5.7 × 103 Ω◻ whereas the optical transparency of the coatings is 88\% with an excellent homogeneity over areas of several cm2. Such results are compatible with most semiconductor fabrication processes and make this method very promising for various industrial applications.}, language = {en} } @inproceedings{MeisterAlSaadiFrankeetal.2010, author = {Meister, Stefan and Al-Saadi, Aws and Franke, B{\"u}lent A. and Mahdi, Shaimaa and Kuhlow, Berndt and Voigt, Karsten and Tillack, Bernd and Richter, Harald H. and Zimmermann, Lars and Ksianzou, Viachaslau and Schrader, Sigurd and Eichler, Hans J.}, title = {Photonic crystal microcavities in SOI waveguides produced in a CMOS environment}, publisher = {Society of Photo-Optical Instrumentation Engineers (SPIE)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-15223}, pages = {330 -- 339}, year = {2010}, abstract = {We have investigated microcavities in Silicon-on-Insolator (SOI) waveguides. The rectangular waveguides with 500 nm width are fabricated in the 220 nm silicon device layer. The microcavities are formed by one-dimensional photonic crystals in Fabry-Perot structure directly written in the waveguides. The SOI photonic structures are produced in a CMOS environment using 248 nm DUV lithography, where the waveguides as well as the photonic crystals are created in the same step using a single mask. In order to achieve a desired spectral shape of the filter function capable for several applications, a number of different cavities were investigated, e.g. single cavities of first and higher order as well as multi-cavity filters. The experimental results are compared with simulations of photonic crystal microcavities in strip waveguides. The spectral transmission function of such filters dependent on the design parameters are calculated by an analysis based on Finite-Difference-Time-Domain (FDTD) method.}, language = {en} } @inproceedings{MeisterSchwedaDziedzinaetal.2010, author = {Meister, Stefan and Schweda, Dawid and Dziedzina, Marcus and Al-Saadi, Aws and Franke, B{\"u}lent A. and Scharfenorth, Chris and Grimm, Bernd and Dufft, Daniela and Schrader, Sigurd and Eichler, Hans J.}, title = {Single cavity filters on end-faces of optical fibers}, publisher = {Society of Photo-Optical Instrumentation Engineers (SPIE)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-15214}, pages = {253 -- 261}, year = {2010}, abstract = {We have developed thin film Fabry-Perot filters directly coated on optical fibers to archive a high level of integration with a reduction of optical elements. Such band-pass filters can be used in fiber optical sensor systems, and for fiber communication, e.g. CWDM applications. The filters cavities consist of a single spacer and two dielectric mirrors. The dielectric mirrors are deposited by PVD directly on end-faces of single-mode optical fibers. Dielectric as well as polymeric materials were applied as the spacer layer. Polymeric spacer layers were deposited by dip coating. The influence of the mirror reflectivity on the transmission band of the Fabry-Perot filters was investigated. Furthermore, the optical performance of filters with first order (λ/2) as well as higher order spacers was analyzed. The experimental results are compared with numerical analysis of Fabry-Perot cavities on the end-face of cylindrical waveguides. The spectral characteristic of the filters are calculated using a software solving Maxwell´s equations by a FDTD method. The layer design of the filters and the deposition process were optimized for maximum transmission and narrow bandwidth of the transmission peak. Passive band-pass filters on fiber end-faces were designed, fabricated and characterized for transmission wavelengths of 945 nm, 1300 nm, as well as 1550 nm. Bandwidths as narrow as 1 nm could be achieved for 945 nm.}, language = {en} } @inproceedings{MeisterAlSaadiFrankeetal.2011, author = {Meister, Stefan and Al-Saadi, Aws and Franke, B{\"u}lent A. and Mahdi, Shaimaa and Szczambura, Miroslaw and Kuhlow, Berndt and Woggon, Ulrike and Zimmermann, Lars and Richter, Harald H. and Stolarek, David and Schrader, Sigurd and Eichler, Hans J.}, title = {Micro-cavities based on width modulated SOI waveguides}, publisher = {Society of Photo-Optical Instrumentation Engineers (SPIE)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-15233}, pages = {199 -- 204}, year = {2011}, abstract = {We have designed, fabricated and investigated one-dimensional (1D) micro-cavities in Silicon-on-Insulator (SOI) waveguides. The single mode waveguides are fabricated in a 220 nm silicon device layer. The 1D micro-cavities in Fabry-Perot structure consist of two Bragg-mirror regions formed by a sinusoidal modulation of the waveguide width. The mirror regions are separated by a sub-micron spacer. The SOI photonic structures are produced in a CMOS environment using 248 nm DUV lithography. The waveguides as well as the width modulated mirror regions are designed using a single mask and are fabricated in a shallow trench process. The transmission spectra of these width modulated micro-cavities with different mirror reflectivities and cavity lengths are investigated. Q-factors up to 855 could be observed at 1550 nm wavelength with low insertion loss of 1.9 dB. The width modulated micro-cavities, including the mirror regions, have lengths of less than 20 microns and widths of maximum 450 nm. These small foot-print cavities act as band pass filters and can be used as resonators for laser or electro-optic modulation of light.}, language = {en} } @inproceedings{WangMeisterMahdietal.2011, author = {Wang, Sha and Meister, Stefan and Mahdi, Shaimaa and Franke, B{\"u}lent A. and Al-Saadi, Aws and Zimmermann, Lars and Richter, Harald H. and Stolarek, David and Lisinetskii, Viktor and Ksianzou, Viachaslau and Schrader, Sigurd and Eichler, Hans J.}, title = {Spontaneous and stimulated Raman scattering in planar silicon waveguides}, publisher = {Society of Photo-Optical Instrumentation Engineers (SPIE)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-15248}, pages = {281 -- 289}, year = {2011}, abstract = {Raman scattering in planar silicon on insulator (SOI) waveguides with 2 μm width, 220 nm height and 2 cm length is investigated. A cw Nd:YAP laser at 1340.6 nm with 7 GHz FWHM spectral width is used as the pump source. A lensed fiber of 2.5 μm focus diameter is used to couple the pump laser into the waveguide. The coupling efficiency is estimated to be around 10\%. Spontaneous Raman scattering is observed with as low as 2.5 mW pump power inside the waveguide. The spontaneous Raman spectrum is measured by an optical spectrum analyzer. The first order Raman peak is measured at around 1441.4 nm corresponding to a Raman shift of 15.6 THz, while the FWHM of Raman spectrum is measured as around 100 GHz. Maximum Raman output of around 90 pW is obtained by around 22 mW pump. The stimulated Raman gain coefficient is estimated as around 56 cm/GW from the relationship between spontaneous Raman output power and pump power. A temperature dependence of Raman frequency shift of about 0.6 GHz/K is measured. The spontaneous anti-Stokes Raman scattering output peak at 1253 nm is also observed with around 35 mW pump. Stimulated Raman amplification measurement is carried out with a SLED white light source as probe signal. With 35 mW pump power, around 0.6 dB gain has been determined with both pump and probe being TE polarized.}, language = {en} } @article{ZeschFinkelsteinRegehlyetal.2026, author = {Zesch, Christoph and Finkelstein, Daniel and Regehly, Martin and Reif, J{\"u}rgen and Schrader, Sigurd}, title = {Efficient nanosecond barium nitrate Raman laser for the visible spectral range}, series = {Optics Express}, volume = {34}, journal = {Optics Express}, number = {4}, publisher = {Optica}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-21320}, pages = {6355 -- 6363}, year = {2026}, abstract = {We report on the design and performance of two solid-state Raman lasers, pumped by a frequency-doubled Nd:YAG laser at 532 nm (8 ns FWHM, 10 Hz, up to 10 mJ), that generate either the first or second Stokes radiation with wavelengths of 563 nm and 598 nm. Barium nitrate crystals with a 1 cm² face area and lengths of 3 cm and 5 cm were used as the Raman-active medium in stable semi-spherical resonators. The Raman lasers produced first Stokes and second Stokes pulses, achieving pulse energies up to 2.3 mJ and conversion efficiencies up to 35\% (first Stokes, 5 cm crystal) and 21\% (second Stokes, 5 cm crystal). The output beams exhibit nearly Gaussian profiles with beam quality factors of M² = 1.67 and M² = 1.83, respectively. The proposed design and characterization demonstrated a Raman laser with high efficiency and superior beam quality. After subsequent frequency doubling, the output appears well dedicated for future differential absorption LiDAR (DIAL) applications.}, language = {en} } @inproceedings{PulwerFiebelkornZeschetal.2019, author = {Pulwer, Silvio and Fiebelkorn, Richard and Zesch, Christoph and Steglich, Patrick and Villringer, Claus and Villasmunta, Francesco and Gedat, Egbert and Handrich, Jan and Schrader, Sigurd and Vandenhouten, Ralf}, title = {Endoscopic orientation by multimodal data fusion}, series = {Proc. SPIE 10931, MOEMS and Miniaturized Systems XVIII}, booktitle = {Proc. SPIE 10931, MOEMS and Miniaturized Systems XVIII}, issn = {1996-756X}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-11420}, year = {2019}, abstract = {To improve the feasibility of endoscopic inspection processes we developed a system that provides online information about position, orientation and viewing direction of endoscopes, to support the analysis of endoscopic images and to ease the operational handling of the equipment. The setup is based on an industrial endoscope consisting of a camera, various MEMS and multimodal data fusion. The software contains algorithms for feature and geometric structure recognition as well as Kalman filters. To track the distal end of the endoscope and to generate 3D point cloud data in real time the optical and photometrical characteristics of the system are registered and the movement of the endoscope is reconstructed by using image processing techniques.}, language = {en} } @inproceedings{ZeschSchraderProspositoetal.2019, author = {Zesch, Christoph and Schrader, Sigurd and Prosposito, Paolo and Lux, Oliver and Eichler, Hans J.}, title = {Raman lasers for trace gas detection}, publisher = {SPIE}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-15351}, pages = {114 -- 119}, year = {2019}, abstract = {The emission of commercial solid-state lasers is shifted by Raman lasers to selected wavelengths suitable for trace gas detection. High power Raman lasers based on Ba(NO3)2, diamond and silicon detect CO2, O3 and H2O. Raman lasers base on the physical effect of stimulated Raman scattering. Two new Raman crystals (Spodumene and LuAlO3) are investigated and their SRS-spectra is shown.}, language = {en} } @article{VillasmuntaHeiseBreiteretal.2026, author = {Villasmunta, Francesco and Heise, Patrick and Breiter, Manuela and Schrader, Sigurd and Schenk, Harald and Regehly, Martin and Mai, Andreas}, title = {Monolithically Integrated Optical Through-Silicon Waveguides for 3D Chip-to-Chip Photonic Interconnects}, series = {IEEE Journal of Selected Topics in Quantum Electronics}, volume = {32}, journal = {IEEE Journal of Selected Topics in Quantum Electronics}, number = {2}, publisher = {IEEE}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-20828}, year = {2026}, abstract = {The scaling limitations of electrical interconnects are driving the demand for efficient optical chip-to-chip links. We report the first monolithic integration of air-clad optical through-silicon waveguides in silicon, fabricated via Bosch and cryogenic deep reactive-ion etching. Rib, single-bridge, and double-bridge designs with 50 μm cores and up to 150 μm propagation lengths have been evaluated. Cryogenic-etched rib waveguides achieve the highest median transmission (66\%, -1.80 dB), compared to Bosch-etched ribs (62\%, -2.08 dB). Across all geometries, 3 dB alignment windows range from 9.3 μm to 49.2 μm, with Bosch-etched double-bridge waveguides providing the broadest tolerance. We show that geometric fidelity outweighs sidewall roughness for transmission and alignment in these large-core, multimode optical through-silicon waveguides. This technology provides a scalable, complementary metal-oxide semiconductor-compatible pathway toward 3D photonic interconnects.}, language = {en} } @article{SteglichMaiVillringeretal.2021, author = {Steglich, Patrick and Mai, Christian and Villringer, Claus and Dietzel, Birgit and Bondarenko, Siegfried and Ksianzou, Viachaslau and Villasmunta, Francesco and Zesch, Christoph and Pulwer, Silvio and Burger, Martin and Bauer, Joachim and Heinrich, Friedhelm and Schrader, Sigurd and Vitale, Francesco and De Matteis, Fabio and Prosposito, Paolo and Casalboni, Mauro and Mai, Andreas}, title = {Silicon-organic hybrid photonics: an overview of recent advances, electro-optical effects and CMOS integration concepts}, series = {Journal of Physics: Photonics}, volume = {3}, journal = {Journal of Physics: Photonics}, number = {2}, issn = {2515-7647}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-13882}, year = {2021}, abstract = {In recent decades, much research effort has been invested in the development of photonic integrated circuits, and silicon-on-insulator technology has been established as a reliable platform for highly scalable silicon-based electro-optical modulators. However, the performance of such devices is restricted by the inherent material properties of silicon. An approach to overcoming these deficiencies is to integrate organic materials with exceptionally high optical nonlinearities into a silicon-on-insulator photonic platform. Silicon-organic hybrid photonics has been shown to overcome the drawbacks of silicon-based modulators in terms of operating speed, bandwidth, and energy consumption. This work reviews recent advances in silicon-organic hybrid photonics and covers the latest improvements to single components and device concepts. Special emphasis is given to the in-device performance of novel electro-optical polymers and the use of different electro-optical effects, such as the linear and quadratic electro-optical effect, as well as the electric-field-induced linear electro-optical effect. Finally, the inherent challenges of implementing non-linear optical polymers on a silicon photonic platform are discussed and a perspective for future directions is given.}, language = {en} } @inproceedings{VillasmuntaSteglichVillringeretal.2024, author = {Villasmunta, Francesco and Steglich, Patrick and Villringer, Claus and Schrader, Sigurd and Schenk, Harald and Mai, Andreas and Regehly, Martin}, title = {Design, fabrication, and characterization of integrated optical through-silicon waveguides for 3D photonic interconnections}, series = {Optical Interconnects XXIV}, volume = {12892}, booktitle = {Optical Interconnects XXIV}, editor = {Chen, Ray T. and Schr{\"o}der, Henning}, publisher = {Society of Photo-Optical Instrumentation Engineers (SPIE)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-19759}, year = {2024}, abstract = {In the context of an ever-growing volume of data generated by established and emerging technologies, such as 5G, the Internet of Things, artificial intelligence, machine learning, blockchain, and virtual reality, faster communication speed is demanded by data centers and high-performance computing. Transceiver requirements surged from 100 to 400 Gb/s and beyond. In this scenario, photonics aims to enable Tb/s optical communication at energies below 1 pJ/bit. Targeting higher communication rates while maintaining a low power budget can significantly benefit from 3D photonic chip architectures. This paper presents the simulation-based design, fabrication, and characterization of a monolithically integrated optical through-silicon waveguide that facilitates the connection between different surfaces of a silicon chip. Deep reactive ion etching was employed in both the Bosch and Cryogenic variants to evaluate the effect of sidewall roughness on propagation losses. The mechanical stability of the waveguide was ensured by interrupting the annular trench with a bridging structure. The high-refractive-index contrast to air provides tight light confinement for a core size of up to 50 μm and multimode operation at 1550 nm. The morphology was characterized using scanning electron microscopy (SEM), and optical transmission characterization was performed using relative power loss measurements. A tunable laser source was buttcoupled to a waveguide to analyze light transmission efficiency. Preliminary measurements using single-mode fiber show that the transmitted values exceeded 99\% for all structures.}, language = {en} } @article{BauerFursenkoMarschmeyeretal.2019, author = {Bauer, Joachim and Fursenko, Oksana and Marschmeyer, Steffen and Heinrich, Friedhelm and Villasmunta, Francesco and Villringer, Claus and Zesch, Christoph and Schrader, Sigurd}, title = {Spectroscopic reflectometry for characterization of Through Silicon Via profile of Bosch etching process}, series = {Journal of Vacuum Science \& Technology B}, volume = {37}, journal = {Journal of Vacuum Science \& Technology B}, number = {6}, publisher = {American Vacuum Society (AVS)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-16093}, year = {2019}, abstract = {Through Silicon Via (TSV) technology is a key in 3D integration of circuits by the creation of interconnects using vias, which go through the full silicon wafer. Typically, a highly-selective Bosch Si etch process is used. It is characterized by a high etch rate at a high aspect ratio, whereby scallops on the sidewalls are generated. In this work, square via arrays with dimensions from 3 to 50 μm and up to 300 μm depth were fabricated and analyzed by spectroscopic reflectometry. The reflectometric data are compared to simulations by a novel theoretical approach. In order to simulate the reflectance spectra of TSV arrays, a combination of 2D and 3D rigorous coupled wave analysis was applied. Besides the via depth, the sidewall angle and the corner radius of the bottom profile were considered in the model. The general requirements on spectral resolution in TSV metrology are discussed.}, language = {en} } @misc{SteglichVillringerPulweretal.2017, author = {Steglich, Patrick and Villringer, Claus and Pulwer, Silvio and Dietzel, Birgit and Ksianzou, Viachaslau and Schrader, Sigurd}, title = {Chip-integrierte photonische Bauelemente}, series = {Wissenschaftliche Beitr{\"a}ge 2017}, volume = {21}, journal = {Wissenschaftliche Beitr{\"a}ge 2017}, issn = {0949-8214}, doi = {10.15771/0949-8214_2017_7}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-9426}, pages = {55 -- 59}, year = {2017}, abstract = {In unserer hochtechnologisierten Gesellschaft spielt die optische Daten{\"u}bertragung aufgrund der stetig wachsenden Informationsvielfalt eine immer bedeutendere Rolle. In den Anf{\"a}ngen der Nachrichtentechnik waren Datenraten von wenigen bit/s realisierbar. Heute werden mittels optischer Technologien {\"U}bertragungsraten von mehreren Gbit/s umgesetzt. M{\"o}glich wird dies durch neue Entwicklungen in der Chip-integrierten Photonik. Beispiele daf{\"u}r sind Chip-integrierte elektrooptische Modulatoren und Schalter. In diesem Artikel werden neue Entwicklungen in der Chip-integrierten Photonik diskutiert und die experimentelle Charakterisierung der Bauelemente in Form eines Ringresonators beschrieben. F{\"u}r die Experimente wird exemplarisch ein photonisches Bauelement genutzt, das aus einem hybriden Silizium-Polymer-Materialsystem besteht. Die Ergebnisse zeigen, dass diese Materialkombination vielversprechend f{\"u}r zuk{\"u}nftige Chip-integrierte photonische Bauelemente mit extrem geringem Energiebedarf ist.}, language = {de} } @misc{SteglichKsianzouVillringeretal.2018, author = {Steglich, Patrick and Ksianzou, Viachaslau and Villringer, Claus and Pulwer, Silvio and Schrader, Sigurd}, title = {Theorie der Modenlinienspektroskopie zur optischen Charakterisierung von Polymerschichten}, series = {Wissenschaftliche Beitr{\"a}ge 2018}, volume = {22}, journal = {Wissenschaftliche Beitr{\"a}ge 2018}, issn = {0949-8214}, doi = {10.15771/0949-8214_2018_4}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-10248}, pages = {31 -- 38}, year = {2018}, abstract = {Die Modenlinienspektroskopie kann zur hochpr{\"a}zisen Charakterisierung von Polymerschichten bez{\"u}glich des Brechungsindex verwendet werden. Das vorliegende Manuskript behandelt die Theorie der Modenlinienspektroskopie und beginnt dabei mit den theoretischen Grundlagen eines planaren Wellenleiters, die zum Verst{\"a}ndnis der Modenlinienspektroskopie notwendig sind. Die hier pr{\"a}sentierten expliziten Herleitungen k{\"o}nnen genutzt werden, um die Modenlinienspektroskopie so zu modifizieren, dass auch die Messung des Pockelseffektes m{\"o}glich ist. Eine Anwendungsm{\"o}glichkeit soll in der zuk{\"u}nftigen Bestimmung des Pockelskoeffizienten bestehen, der f{\"u}r die Weiterentwicklung von polymerbasierten elektrooptischen Modulatoren ben{\"o}tigt wird. Zudem werden der Aufbau und die experimentelle Herangehensweisen beschrieben und die Brechungsindexbestimmung wird exemplarisch am Beispiel einer Wirt-Gast-Polymerschicht demonstriert.}, language = {de} } @article{SteglichMaiVillringeretal.2018, author = {Steglich, Patrick and Mai, Christian and Villringer, Claus and Pulwer, Silvio and Casalboni, Mauro and Schrader, Sigurd and Mai, Andreas}, title = {Quadratic electro-optic effect in silicon-organic hybrid slot-waveguides}, series = {Optics Letters}, volume = {43}, journal = {Optics Letters}, number = {15}, issn = {1539-4794}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-12148}, year = {2018}, abstract = {This Letter reports on the quadratic electro-optic effect of polymers, observed in a silicon slot-waveguide at low voltages. We demonstrate that in narrow slots, the electro-optic response with respect to refractive index change is strong enough for on-chip wavelength tuning and intensity modulation using voltages as low as 1 V. A silicon slot-waveguide embedded by a nonlinear optical polymer, consisting of the dye Disperse Red 1 in poly(methyl methacrylate), serves as the phase shifter in a racetrack ring resonator. As deduced from the experimental data, the third-order susceptibility of the utilized electro-optic polymer is about 2·10-19 m2/V2. The demonstrated low-voltage operation and inherently thermal stability show the potential for silicon-organic hybrid devices using the quadratic electro-optic effect.}, language = {en} }