@article{29201, abstract = {{As a complementary technology to existing Radio Frequency (RF)-based solutions such as Cellular V2X (C-V2X) and Dedicated Short Range Communication (DSRC), Vehicular VLC (V-VLC) is gaining more attention in the research community as well as in the industry. This paper introduces a complete IEEE 802.11 compliant V-VLC system. The system relies on Universal Software Radio Peripheral (USRP) software defined radios programmed using the GNU Radio framework, a typical car headlight plus a custom driver electronics for the high-power car LEDs (sender), and a photodiode (receiver). Building upon our earlier work, we, for the first time, experimentally explore the communication performance in outdoor scenarios, even in broad daylight, and show that rather simple optical modifications help to reduce the ambient noise to enable long distance visible light communication. Our system also supports Orthogonal Frequency-Division Multiplexing (OFDM) with a variety of Modulation and Coding Schemes (MCS) up to 64-QAM and is fully compliant with IEEE 802.11. We performed an extensive series of experiments to explore the performance of our system, even using higher order MCS in daylight. Our results demonstrated a high reliability for distances up to 75m with the presented system, regardless of the time of the day.}}, author = {{Amjad, Muhammad Sohaib and Tebruegge, Claas and Memedi, Agon and Kruse, Stephan and Kress, Christian and Scheytt, J. Christoph and Dressler, Falko}}, journal = {{IEEE Transactions on Vehicular Technology}}, number = {{6}}, pages = {{5749--5761}}, title = {{{Towards an IEEE 802.11 Compliant System for Outdoor Vehicular Visible Light Communications}}}, doi = {{10.1109/TVT.2021.3075301}}, volume = {{70}}, year = {{2021}}, } @article{23993, author = {{Bahmanian, Meysam and Scheytt, Christoph}}, journal = {{IEEE Transactions on Microwave Theory and Techniques}}, number = {{3}}, pages = {{1635--1645}}, title = {{{A 2-20-GHz Ultralow Phase Noise Signal Source Using a Microwave Oscillator Locked to a Mode-Locked Laser}}}, doi = {{10.1109/tmtt.2020.3047647}}, volume = {{69}}, year = {{2021}}, } @inproceedings{29205, abstract = {{We present the optical generation of a 300 Gbaud PRBS-7 data signal based on time-division multiplexing of Nyquist sinc-pulse sequences. The employed electronic and photonic components need only one-third of the final bandwidth.}}, author = {{Singh, Karanveer and Meier, Janosch and Preussler, Stefan and Kress, Christian and Scheytt, J. Christoph and Schneider, Thomas}}, booktitle = {{OSA Advanced Photonics Congress 2021}}, isbn = {{978-1-943580-94-1}}, location = {{Washington, DC United States}}, pages = {{SpTu4D.6}}, publisher = {{Optical Society of America}}, title = {{{Optical PRBS Generation with Threefold Bandwidth of the Employed Electronics and Photonics}}}, doi = {{https://doi.org/10.1364/SPPCOM.2021.SpTu4D.6}}, year = {{2021}}, } @article{29202, author = {{De, Souvaraj and Singh, Karanveer and Kress, Christian and Das, Ranjan and Schwabe, Tobias and Preußler, Stefan and Kleine-Ostmann, Thomas and Scheytt, J. Christoph and Schneider, Thomas}}, journal = {{IEEE Photonics Technology Letters}}, number = {{21}}, pages = {{1189--1192}}, title = {{{Roll-Off Factor Analysis of Optical Nyquist Pulses Generated by an On-Chip Mach-Zehnder Modulator}}}, doi = {{10.1109/LPT.2021.3112485}}, volume = {{33}}, year = {{2021}}, } @article{29209, abstract = {{We demonstrate an optical arbitrary waveform measurement (OAWM) system that exploits a bank of silicon photonic (SiP) frequency-tunable coupled-resonator optical waveguide (CROW) filters for gapless spectral slicing of broadband optical signals. The spectral slices are coherently detected using a frequency comb as a multi-wavelength local oscillator (LO) and stitched together by digital signal processing (DSP). For high-quality signal reconstruction, we have implemented a maximum-ratio combining (MRC) technique based on precise calibration of the complex-valued opto-electronic transfer functions of all detection paths. In a proof-of-concept experiment, we demonstrate the viability of the scheme by implementing a four-channel system that offers an overall detection bandwidth of 140 GHz. Exploiting a femtosecond laser with precisely known pulse shape for calibration along with dynamic amplitude and phase estimation, we reconstruct 100 GBd QPSK, 16QAM and 64QAM optical data signals. The reconstructed signals show improved quality compared to that obtained with a single high-speed intradyne receiver, while the electronic bandwidth requirements of the individual coherent receivers are greatly reduced.}}, author = {{Fang, Dengyang and Zazzi, Andrea and Müller, Juliana and Dray, Daniel and Fullner, Christoph and Marin-Palomo, Pablo and Tabatabaei Mashayekh, Alireza and Dipta Das, Arka and Weizel, Maxim and Gudyriev, Sergiy and Freude, Wolfgang and Randel, Sebastian and Scheytt, J. Christoph and Witzens, Jeremy and Koos, Christian}}, issn = {{0733-8724}}, journal = {{Journal of Lightwave Technology}}, keywords = {{Atomic and Molecular Physics, and Optics}}, pages = {{1--1}}, publisher = {{Institute of Electrical and Electronics Engineers (IEEE)}}, title = {{{Optical Arbitrary Waveform Measurement Using Silicon Photonic Slicing Filters}}}, doi = {{10.1109/jlt.2021.3130764}}, year = {{2021}}, } @article{29211, abstract = {{Electrical-optical signal processing has been shown to be a promising path to overcome the limitations of state-of-the-art all-electrical data converters. In addition to ultra-broadband signal processing, it allows leveraging ultra-low jitter mode-locked lasers and thus increasing the aperture jitter limited effective number of bits at high analog signal frequencies. In this paper, we review our recent progress towards optically enabled time- and frequency-interleaved analog-to-digital converters, as well as their monolithic integration in electronic-photonic integrated circuits. For signal frequencies up to 65 GHz, an optoelectronic track-and-hold amplifier based on the source-emitter-follower architecture is shown as a power efficient approach in optically enabled BiCMOS technology. At higher signal frequencies, integrated photonic filters enable signal slicing in the frequency domain and further scaling of the conversion bandwidth, with the reconstruction of a 140 GHz optical signal being shown. We further show how such optically enabled data converter architectures can be applied to a nonlinear Fourier transform based integrated transceiver in particular and discuss their applicability to broadband optical links in general.}}, author = {{Zazzi, Andrea and Müller, Juliana and Weizel, Maxim and Koch, Jonas and Fang, Dengyang and Moscoso-Martir, Alvaro and Tabatabaei Mashayekh, Ali and Das, Arka D. and Drays, Daniel and Merget, Florian and Kartner, Franz X. and Pachnicke, Stephan and Koos, Christian and Scheytt, J. Christoph and Witzens, Jeremy}}, issn = {{2644-1349}}, journal = {{IEEE Open Journal of the Solid-State Circuits Society}}, pages = {{209--221}}, publisher = {{Institute of Electrical and Electronics Engineers (IEEE)}}, title = {{{Optically Enabled ADCs and Application to Optical Communications}}}, doi = {{10.1109/ojsscs.2021.3110943}}, volume = {{1}}, year = {{2021}}, } @article{29212, author = {{Fang, Dengyang and Zazzi, Andrea and Müller, Juliana and Daniel, Drayß and Füllner, Christoph and Marin-Palomo, Pablo and Mashayekh, Ali Tabatabaei and Das, Arka Dipta and Weizel, Maxim and Gudyriev, Sergiy and Freude, Wolfgang and Randel, Sebastian and Scheytt, J. Christoph and Witzens, Jeremy and Koos, Christian}}, isbn = {{978-1-943580-86-6}}, journal = {{OSA Technical Digest}}, title = {{{Optical Arbitrary Waveform Measurement (OAWM) on the Silicon Photonic Platform}}}, doi = {{10.1109/JLT.2021.3130764}}, year = {{2021}}, } @article{23476, author = {{Weizel, Maxim and Scheytt, J. Christoph and Kärtner, Franz X. and Witzens, Jeremy}}, issn = {{1094-4087}}, journal = {{Optics Express}}, title = {{{Optically clocked switched-emitter-follower THA in a photonic SiGe BiCMOS technology}}}, doi = {{10.1364/oe.425710}}, year = {{2021}}, } @phdthesis{6563, abstract = {{Designprozesse von Schallwandlern werden durch zunehmende Rechenkapazitäten immer mehr durch simulative Betrachtungen unterstützt. Dabei ist vor allem die Wahl der Materialparameter der verwendeten Materialien wichtig für ein realitätsnahes Simulationsergebnis. Bei Schallwandlern werden häufig Piezokeramiken als aktive Elemente genutzt, welche sich durch eine Verkopplung mechanischer und elektrischer Eigenschaften auszeichnen. Zur Bestimmung ihrer Materialparameter stellt der IEEE Standard on Piezoelectricity ein standardisiertes Verfahren dar. Dazu sind fünf Impedanzmessungen an vier unterschiedlich gefertigten Probekörpergeometrien notwendig. Da an jedem einzelnen Probekörper nur eine Untermenge aller notwendigen Materialparameter bestimmt werden kann, werden diese dann zu einem kompletten Materialparametersatz zusammengefügt. Aufgrund der unterschiedlichen Prozessbedingungen, bei denen die jeweiligen Probekörper hergestellt werden, ist dieser Materialparametersatz jedoch inkonsistent und kann nie das Verhalten einer einzelnen Probe beschreiben. Daher wird in der vorliegenden Arbeit ein Messverfahren entwickelt, mit dem es möglich ist, alle relevanten Materialparameter unter besonderer Berücksichtigung von Dämpfung an einem einzelnen Probekörper allein durch Impedanzmessungen zu bestimmen. Als Probekörper wird dazu eine in der Anwendung häufig verwendete Scheibengeometrie verwendet. Um eine hinreichend hohe Sensitivität auf alle Materialparameter zu gewährleisten, wird diese mit einer optimierten Elektrodentopologie gefertigt. Da in diesem Fall keine analytische Betrachtung mehr möglich ist, wird das Messverfahren durch einen inversen Ansatz realisiert.}}, author = {{Feldmann, Nadine}}, pages = {{184}}, publisher = {{Universität Paderborn}}, title = {{{ Ein modellbasiertes Messverfahren zur Charakterisierung von Piezokeramiken unter Verwendung eines einzelnen scheibenförmigen Probekörpers}}}, doi = {{10.17619/UNIPB/1-1264}}, year = {{2021}}, } @article{21341, abstract = {{The progress in numerical methods and simulation tools promotes the use of inverse problems in material characterisation problems. A newly developed procedure can be used to identify the behaviour of piezoceramic discs over a wide frequency range using a single specimen via fitting simulated and measured impedances by optimising the underlying material parameters. Since there is no generally accepted damping model for piezoelectric ceramics, several mechanical damping models are examined for the material identification. Three models have been chosen and their ability to replicate the measured impedances is evaluated. On the one hand, the common Rayleigh model is considered as a reference. On the other hand, a Zener model and a model using complex constants are extended to model the transversely isotropic material. As the Rayleigh model is only valid for a limited frequency range, it fails to model the broadband behaviour of the material. The model using complex constants leads to the best fit over a wide frequency range while at the same time only adding three additional parameters for modelling damping. Thus, damping can be assumed approximately frequency-independent in piezoceramics.}}, author = {{Feldmann, Nadine and Schulze, Veronika and Claes, Leander and Jurgelucks, Benjamin and Meihost, Lars and Walther, Andrea and Henning, Bernd}}, issn = {{2196-7113}}, journal = {{tm - Technisches Messen}}, number = {{5}}, pages = {{294 -- 302}}, title = {{{Modelling damping in piezoceramics: A comparative study}}}, doi = {{10.1515/teme-2020-0096}}, volume = {{88}}, year = {{2021}}, } @inproceedings{22012, author = {{Claes, Leander and Feldmann, Nadine and Jurgelucks, Benjamin and Schulze, Veronika and Schmidt, Stephan and Walther, Andrea and Henning, Bernd}}, location = {{Nürnberg}}, pages = {{237--238}}, title = {{{Optimised Multi-Electrode Topology for Piezoelectric Material Characterisation}}}, doi = {{10.5162/SMSI2021/A10.1}}, year = {{2021}}, } @misc{21233, author = {{Schulze, Veronika and Schmidt, Stephan and Jurgelucks, Benjamin and Feldmann, Nadine and Claes, Leander}}, title = {{{Optimal experiment design with respect to electrode configurations for a piezoelectric problem}}}, year = {{2021}}, } @misc{23462, author = {{Schulze, Veronika and Schmidt, Stephan and Jurgelucks, Benjamin and Feldmann, Nadine and Claes, Leander}}, title = {{{Piezoelectric BC Modeling for Electrode Shapes with OED}}}, year = {{2021}}, } @article{20189, abstract = {{A dielectric step-index optical fiber with tube-like profile is considered, being positioned with a small gap on top of a dielectric slab waveguide. We propose a 2.5-D hybrid analytical/numerical coupled mode model for the evanescent excitation of the tube through semi-guided waves propagating in the slab at oblique angles. The model combines the directional polarized modes supported by the slab with analytic solutions for the TE-, TM-, and orbital-angular-momentum (OAM) modes of the tube-shaped fiber. Implementational details of the scheme are discussed, complemented by finite-element simulations for verification purposes. Our results include configurations with resonant in-fiber excitation of OAM modes with large orbital angular momentum and strong field enhancement.}}, author = {{Hammer, Manfred and Ebers, Lena and Förstner, Jens}}, issn = {{0306-8919}}, journal = {{Optical and Quantum Electronics}}, keywords = {{tet_topic_waveguides}}, title = {{{Hybrid coupled mode modelling of the evanescent excitation of a dielectric tube by semi-guided waves at oblique angles}}}, doi = {{10.1007/s11082-020-02595-z}}, volume = {{52}}, year = {{2020}}, } @article{20233, abstract = {{The challenge of designing new tunable nonlinear dielectric materials with tailored properties has attracted an increasing amount of interest recently. Herein, we study the effective nonlinear dielectric response of a stochastic paraelectric-dielectric composite consisting of equilibrium distributions of circular and partially penetrable disks (or parallel, infinitely long, identical, partially penetrable, circular cylinders) of a dielectric phase randomly dispersed in a continuous matrix of a paraelectric phase. The random microstructures were generated using the Metropolis Monte Carlo algorithm. The evaluation of the effective permittivity and tunability were carried out by employing either a Landau thermodynamic model or its Johnson’s approximation to describe the field-dependent permittivity of the paraelectric phase and solving continuum-electrostatics equations using finite element calculations. We reveal that the percolation threshold in this composite governs the critical behavior of the effective permittivity and tunability. For microstructures below the percolation threshold, our simulations demonstrate a strong nonlinear behaviour of the field-dependent effective permittivity and very high tunability that increases as a function of dielectric phase concentration. Above the percolation threshold, the effective permittivity shows the tendency to linearization and the tunability dramatically drops down. The highly reduced permittivity and extraordinarily high tunability are obtained for the composites with dielectric impenetrable disks at high concentrations, in which the triggering of the percolation transition is avoided. The reported results cast light on distinct nonlinear behaviour of 2D and 3D stochastic composites and can guide the design of novel composites with the controlled morphology and tailored permittivity and tunability.}}, author = {{Myroshnychenko, Viktor and Smirnov, Stanislav and Jose, Pious Mathews Mulavarickal and Brosseau, Christian and Förstner, Jens}}, issn = {{1359-6454}}, journal = {{Acta Materialia}}, pages = {{116432}}, title = {{{Nonlinear dielectric properties of random paraelectric-dielectric composites}}}, doi = {{10.1016/j.actamat.2020.10.051}}, volume = {{203}}, year = {{2020}}, } @inproceedings{24022, abstract = {{In this paper we propose a novel low-power receiver architecture which uses a direct-detection receiver in combination with a 2.44 GHz 13 bit Barker Code SAW correlator for improvement of co-channel interference. Furthermore, to improve receiver sensitivity, a narrowband baseband correlator which uses pulse position modulation (PPM) is proposed. The receiver can be used as a Wake-up Receiver (WuRx) in Wireless Sensor Networks (WSN) to minimize the power dissipation and provide asynchronous and on-demand data communication. We present a rigorous analysis of the receiver. It shows that the RF front-end (SAW correlator and envelope detector) alone suffers from poor sensitivity due to the high baseband bandwidth and the absence of an RF low noise amplifier. However, by adding the narrowband correlator with an innovative Pulse Position Modulation (PPM) scheme, the overall sensitivity of the receiver reaches -63.1 dB with an improvement of 17.7 dB due to the use of the narrowband correlator that reduces the baseband bandwidth from 50 to 0.84 MHz. By scaling the narrowband correlator bandwidth further down, the receiver sensitivity can be further improved.}}, author = {{Abughannam, Saed and Scheytt, Christoph}}, booktitle = {{IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC 2020) }}, publisher = {{IEEE}}, title = {{{Sensitivity Analysis of a Low-Power Wake-Up Receiver Using an RF Barker Code SAW Correlator and a Baseband Narrowband Correlator}}}, doi = {{10.1109/PIMRC48278.2020.9217198}}, year = {{2020}}, } @inproceedings{24027, abstract = {{Fault effect simulation is a well-established technique for the qualification of robust embedded software and hardware as required by different safety standards. Our article introduces a Virtual Prototype based approach for the fault analysis and fast simulation of a set of automatically generated and target compiled software programs. The approach scales to different RISC-V ISA standard subset configurations and is based on an instruction and hardware register coverage for automatic fault injections of permanent and transient bitflips. The analysis of each software binary evaluates its opcode type and register access coverage including the addressed memory space. Based on this information dedicated sets of fault injected hardware models, i.e., mutants, are generated. The simulation of all mutants conducted with the different binaries finally identifies the cases with a normal termination though executed on a faulty hardware model. They are identified as a subject for further investigations and improvements by the implementation of additional hardware or software safety countermeasures. Our final evaluation results with automatic C code generation, compilation, analysis, and simulation show that QEMU provides an adequate efficient platform, which also scales to more complex scenarios.}}, author = {{Adelt, Peer and Koppelmann, Bastian and Müller, Wolfgang and Scheytt, Christoph}}, booktitle = {{MBMV 2020 - Methods and Description Languages for Modelling and Verification of Circuits and Systems; GMM/ITG/GI-Workshop}}, title = {{{A Scalable Platform for QEMU Based Fault Effect Analysis for RISC-V Hardware Architectures}}}, year = {{2020}}, } @inproceedings{24030, abstract = {{Low-power receivers use direct-detection receiver architecture for its design simplicity and its low power dissipation. However, the direct-detection based receivers suffer from co-channel interference which significantly degrades the communication reliability. Co-channel interference robustness can be improved by using a BPSK Barker code modulated Surface Acoustic Wave (SAW) correlator as a prior stage to the RF direct detection circuit. This paper reports in details the design, fabrication and measurements of a 2.45 GHz SAW correlator with 13 bits length Barker code. The device is fabricated on Lithium Niobate LiNbO3 substrate and it is composed of an input non-coded Inter Digital Transducers (IDT), a Piezoelectric substrate and an output coded IDT. The device wavelength λ is set to 1.6 μm, considering a phase velocity of the wave equal to 3970 m.s-1. Several configurations of the device were designed and fabricated, particularly varying the aperture and the non-coded IDT length to find out the optimal device configuration. All devices were found to operate with Insertion Loss (IL) ranging from 12 to 15 dB at 2.45 GHz with a tip probing measurement setup, while a packaged sample has an IL of 12.45 dB at 2.44 GHz mounted on a PCB with external 50 Ω LC matching network. Additionally, time-domain measurement for the packaged device shows that the output has a correlation peak with a peak-to-side-lobe (PSL) ratio of 4:1 for a -0.5 dBm input BPSK Barker code signal.}}, author = {{Ballandras, Sylvain and Abughannam, Saed and Courjon, Emilie and Scheytt, Christoph}}, booktitle = {{GeMiC 2020 - German Microwave Conference}}, title = {{{Design and Fabrication of Barker Coded Surface Acoustic Wave (SAW) Correlator at 2.45 GHz for Low-Power Wake-up Receivers}}}, year = {{2020}}, } @inproceedings{21541, abstract = {{In this publication, the near-field to far-field transformation using the self-built near-field scanner NFS3000 is examined with regard to its geometry. This device allows to measure electric and magnetic fields in small distances to the DUT (Device under Test) with high geometric precision and high sensitivity. Leading to a fast examination of EMC (Electromagnetic Compatibility) problems, because the electromagnetic properties are better understandable and therefore easier to solve than e.g. measurements in a far-field chamber. In addition, it is possible to extrapolate the near-fields into the far-field and to determine the radiation pattern of antennas and emitting objects. For this purpose, this paper deals with the basis of this transformation, the so-called surface equivalence theorem. This principle is then adapted to the measurement of near-field scanners and implemented accordingly. Due to the non-ideal design of the near-field scanner, the effects on a far-field transformation are finally presented and discussed.}}, author = {{Lange, Sven and Schroder, Dominik and Hedayat, Christian and Hangmann, Christian and Otto, Thomas and Hilleringmann, Ulrich}}, booktitle = {{2020 International Symposium on Electromagnetic Compatibility - EMC EUROPE}}, isbn = {{978-1-7281-5580-7}}, issn = {{2325-0364 }}, keywords = {{Near-Field Scanner, Near-Field to Far-Field Transformation, Directivity, Surface Equivalence Theorem, Huygens’ Box}}, location = {{Rome, Italy }}, publisher = {{IEEE}}, title = {{{Investigation of the Surface Equivalence Principle on a Metal Surface for a Near-Field to Far-Field Transformation by the NFS3000}}}, doi = {{10.1109/emceurope48519.2020.9245697}}, year = {{2020}}, } @inbook{17352, author = {{Moritzer, Elmar and Hüttner, Matthias and Henning, Bernd and Webersen, Manuel}}, booktitle = {{Advances in Polymer Processing 2020}}, editor = {{Hopmann, Christian and Dahlmann, Rainer}}, isbn = {{9783662608081}}, location = {{Aachen}}, publisher = {{Springer}}, title = {{{The Influence of Hydrothermal Aging on the Material Properties of Continuous Fiber-Reinforced Thermoplastics and its Non-Destructive Characterization}}}, doi = {{10.1007/978-3-662-60809-8_16}}, year = {{2020}}, }