Recent publications

March 2023

Microwave Photonic ps-Pulse and 140 GHz RF Comb Generator

Hendrik Boerma, Felix Ganzer, Patrick Runge, Martin Schell, Edgar Fernandes, Benjamin Rudin, Florian Emaury

A microwave photonic RF comb generator is presented by combining an fs-pulse laser and a high-speed broadband photodetector module. The subsystem generates pulses with a FWHM of 5.8 ps and a flat RF comb up to 140 GHz. Furthermore, the...

March 2023

System for 3D Acquisition and 3D Reconstruction Using Structured Light for Sewer Line Inspection

Johannes Wolf Künzel, Peter Eisert, Anna Hilsmann, Karl-Heinz Franke, Darco Vehar, Rico Nestler

We introduce an innovative system based on single-shot structured light modules that facilitates the detection and classification of spatial defects like jutting intrusions, spallings, or misaligned joints. This system creates highly accurate 3D...

February 2023

Decentral and Incentivized Federated Learning Frameworks: A Systematic Literature Review

Leon Witt, Wojciech Samek, Mathis Heyer, Kentaroh Toyoda, Dan Li

The advent of federated learning (FL) has sparked a new paradigm of parallel and confidential decentralized machine learning (ML) with the potential of utilizing the computational power of a vast number of Internet of Things (IoT), mobile, and...

January 2023

Quantus: An Explainable AI Toolkit for Responsible Evaluation of Neural Network Explanations and Beyond

Anna Hedström, Wojciech Samek, Sebastian Lapuschkin, Leander Weber, Dilyara Bareeva, Franz Motzkus, Marina M.-C. Höhne, Daniel Krakowczyk

Explainability is supposed to strengthen trust in artificial intelligence, it is necessary to systematically review and compare explanation methods in order to confirm their correctness. We therefore built Quantus—a comprehensive, evaluation...

January 2023

Enabling Optical Modulation Format Identification Using an Integrated Photonic Reservoir and a Digital Multiclass Classifier

Guillermo von Hünefeld, Colja Schubert, Ronald Freund, Isaac Sackey, Gregor Ronniger, Johannes K. Fischer, Pooyan Safari, Rijil Thomas, Enes Seker, Piotr Cegielski, Stephan Suckow, Max Lemme, David Stahl, Sarah Masaad, Emmanuel Gooskens, Peter Bienstman

We numerically show modulation format identification in the optical domain using Silicon-on-Insulator-based Photonic-Integrated-Circuit (PIC) reservoir. Identification of 32 GBd single-polarization signals of OOK, PAM4, BPSK and QPSK is...

January 2023

Ultrafast quantum key distribution using fully parallelized quantum channels

Robin Terhaar, Nicolas Perlot, Jasper Rödiger, Fabian Beutel, M. Wolff, Jonas Hanke, Nino Walenta, W. Hartmann, M. Häußler, M. Wahl, T. Röhlicke, W. H. P. Pernice, C. Schuck, Helge Gehring, Nicolai Walter, Peter Hanne, Maximilian Diedrich, Max Tillmann, Mahdi Ahangarianabhari

Quantum key distribution (QKD) offers secure communication protected by the laws of quantum mechanics. Aiming for an application-oriented solution, we designed a multichannel superconducting nanowire single photon detector system, as well as a...

January 2023

Continuous intraoperative perfusion monitoring of free microvascular anastomosed fasciocutaneous flaps using remote photoplethysmography

Sebastian Schraven, Peter Eisert, Anna Hilsmann, Eric Wisotzky, Benjamin Kossack, Maximilian Jung, Lotte Skopnik, Robert Mlynski, Daniel Strüder, Justus Groß

Intraoperative monitoring of free flaps using remote photoplethysmography (rPPG) signal provides objective and reproducible data on tissue perfusion. We developed a monitoring algorithm for flap perfusion, which was evaluated in fifteen patients...

January 2023

Investigating the Performance and Suitability of Neural Network Architectures for Nonlinearity Mitigation of Optical Signals

Vegenshanti Valerian Dsilva, Colja Schubert, Ronald Freund, Isaac Sackey, Gregor Ronniger, Guillermo von Hünefeld, Binoy Chacko

We compare three different neural network architectures for nonlinearity mitigation of 32 GBd OOK and QPSK signals after transmission over a dispersion-compensated link of 10-km SSMF and 10-km DCF. OSNR gains up to 2.2 dB were achieved using...

January 2023

Experimental Study of In-line Nonlinearity Mitigation for a 400 Gb/s Dual-Carrier Superchannel with Joint Reception Using a Waveband-Shift-Free OPC

Isaac Sackey, Colja Schubert, Carsten Schmidt-Langhorst, Ronald Freund, Robert Elschner, Tomoyuki Kato, Takeshi Hoshida, Gregor Ronniger

We experimentally study waveband-shift-free optical phase conjugation (OPC) of a 400-Gb/s dual-carrier superchannel and discuss the effectiveness of the OPC for multi-channel nonlinear mitigation. After joint reception of the 31.44 GBd-PDM-16QAM...

January 2023

Ultra-Wideband All-optical Interband Wavelength Conversion Using a Low-complexity Dispersion-engineered SOI Waveguide

Isaac Sackey, Colja Schubert, Carsten Schmidt-Langhorst, Ronald Freund, Robert Elschner, Tomoyuki Kato, Takeshi Hoshida, Gregor Ronniger, Hidenobu Muranaka, Shun Okada, Yu Tanaka, Tsuyoshi Yamamoto, Md Mahasin KhanIsaac Sackey, Colja Schubert, Carsten Schmidt-Langhorst, Ronald Freund, Robert Elschner, Tomoyuki Kato, Takeshi Hoshida, Gregor Ronniger, Hidenobu Muranaka, Shun Okada, Yu Tanaka, Tsuyoshi Yamamoto, Md Mahasin Khan

We experimentally present a low-complexity dispersion-engineered all-optical wavelength-converter using a photonic integrated-circuit based on SOI waveguide. We achieve a single-sided conversion bandwidth of ~35 nm from C- to S-band, and...

December 2022

Increasing the reach of visible light communication links through constant-envelope OFDM signals

Higor Camporez, Volker Jungnickel, Ronald Freund, Anagnostis Paraskevopoulos, Malte Hinrichs, Wesley Da Silva Costa, Maria Pontes, Marcelo Segatto, Helder Rocha, Jair Silva

We demonstrate the transmission of constant-envelope orthogonal frequency division multiplexing (CE-OFDM) signals, based on electrical phase modulation, in a visible light communication (VLC) system. An increased tolerance to nonlinearity...

December 2022

A Novel Approach for Joint Analytical and ML-assisted GSNR Estimation in Flexible Optical Network

Farhad Arpanaei, Johannes K. Fischer, Mohammad Behnam Shariati, Pooyan Safari, Mahdi Ranjbar Zefreh, José Alberto Hernández, Andrea Carena, David Larrabeiti

We propose a novel approach to perform QoT estimation relying on joint exploitation of machine learning and analytical formula that offers accurate estimation when applied to scenarios with heterogeneous span profiles and sparsely occupied links....

December 2022

Automated Dataset Generation for QoT Estimation in Coherent Optical Communication Systems

Caio Marciano Santos, Colja Schubert, Carsten Schmidt-Langhorst, Robert Emmerich, Johannes K. Fischer, Mohammad Behnam Shariati

We demonstrate sophisticated laboratory automation and data pipeline capable of generating large, diverse, and high-quality public datasets. The demo covers the full workflow from setup reconfiguration to data monitoring and storage, represented...

December 2022

Demonstration of a Real-Time ML Pipeline for Traffic Forecasting in AI-Assisted F5G Optical Access Networks

Mihail Balanici, Ronald Freund, Johannes K. Fischer, Mohammad Behnam Shariati, Pooyan Safari, Geronimo Bergk

We showcase a proof-of-concept demonstration of a ML pipeline for real-time traffic forecasting deployed on a passive optical access network using an XGS-PON compatible telemetry framework. The demonstration reveals the benefits of fine-granular...

December 2022

Toward AI-enhanced VLC Systems for Industrial Applications

Wesley Da Silva Costa, Volker Jungnickel, Ronald Freund, Anagnostis Paraskevopoulos, Malte Hinrichs, Higor Camporez, Maria Pontes, Marcelo Segatto, Helder Rocha, Jair Silva

This paper presents optimization and deep learning procedures aiming at increasing power and spectral efficiency of visible light communications systems for two exemplary industrial scenarios. We propose a hybrid multi-objective optimization to...

December 2022

Demonstration of 1.75 Gbit/s VCSEL-Based Non-Directed Optical Wireless Communications With OOK and FDE

Malte Hinrichs, Volker Jungnickel, Martin Schubert, Wen Xu, Ronald Freund, Christoph Kottke, Dominic Schulz, Peter Hellwig, Ronald Böhnke, Giulio Boniello

We evaluate a high power on-off-keying transmitter for non-directed optical wireless communications based on VCSEL-arrays. Error-free transmission after FEC with a net data rate of 1.75 GBit/s is achieved across a distance of 2.5 m with a...

December 2022

Comparison of Uni- and Multimodal Interfaces for Spatial Interaction

David Przewozny, Sebastian Bosse, Detlef Runde, Paul Chojecki, Niklas Gard, Niklas Hoerner

Multimodal user interfaces can provide better solutions, as they combine various interaction modalities to enable more flexibility and naturalness in human-machine interactions (HMI). They allow to seamlessly adapt to user and application...

December 2022

Reducing Overhead for Low-Power Optical Wireless Communications

Malte Hinrichs, Volker Jungnickel, Peter Hellwig, Benjamin Poddig

We demonstrate on-off-keying optical wireless transmissions according to the IEEE P802.15.13 PM-PHY, in which we replace 8b10b line-coding by guided and non-guided data scramblers and compensate the remaining high-pass distortions through a...

December 2022

Explaining the Decisions of Convolutional and Recurrent Neural Networks

Wojciech Samek, Klaus-Robert Müller, Leila Arras, Grégoire Montavon, Ahmed Osman

In this chapter we discuss the algorithmic and theoretical underpinnings of layer-wise relevance propagation (LRP), apply the method to a complex model trained for the task of visual question answering (VQA), and demonstrate that it produces...

December 2022

Beyond Explaining: Opportunities and Challenges of XAI-Based Model Improvement

Leander Weber, Wojciech Samek, Alexander Binder, Sebastian Lapuschkin

Explainable Artificial Intelligence (XAI) is an emerging research field bringing transparency to highly complex and opaque machine learning (ML) models. This paper offers a comprehensive overview over techniques that apply XAI practically to...

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