Recent publications

September 2021

Influence of losses on the Laser Voltage drop of the active section

Magnus Happach, Norbert Keil, Martin Schell, Moritz Kleinert, Walter Brinker, Crispin Zawadzki, Martin Moehrle, David de Felipe Mesquida, Martin Kresse, Gelani Irmscher, Werner Hofmann, Victor Nicolai Friedhoff

A model of a tunable distributed Bragg reflector (DBR) laser describing the effect of cavity losses on the gain voltage is presented. Theoretical and experimental results are in good agreement. Measurements show the gain voltage trace for Bragg...


September 2021

Influence of losses on the Laser Voltage drop of the active section

Magnus Happach, Norbert Keil, Martin Schell, Moritz Kleinert, Walter Brinker, Crispin Zawadzki, Martin Moehrle, David de Felipe Mesquida, Martin Kresse, Gelani Irmscher, Werner Hofmann, Victor Nicolai Friedhoff

A model of a tunable distributed Bragg reflector (DBR) laser describing the effect of cavity losses on the gain voltage is presented. Theoretical and experimental results are in good agreement. Measurements show the gain voltage trace for Bragg...


September 2021

2D Optical Phased Arrays for Laser Beam Steering Based on 3D Polymer Photonic Integrated Circuits

Adam Raptakis, Christos Kouloumentas, Moritz Kleinert, Hercules Avramopoulos, Norbert Keil, Panos Groumas, Lefteris Gounaridis, Christos Tsokos, Madeleine Weigel, Michalis Georgiopoulos, Elias Mylonas

A novel concept for the implementation of 2-dimensional (2D) optical phased arrays (OPAs) with end-fire waveguides as antenna elements (AEs) is proposed and its theoretical model and experimental proof is presented. The concept is based on the...


September 2021

COMPASS: localization in laparoscopic visceral surgery

Regine Hartwig, Jean-Claude Rosenthal, Dirk Wilhelm, Hubertus Feussner, Daniel Ostler, Maximilian Berlet, Kevin Yu

Tracking of surgical instruments is an essential step towards the modernization of the surgical workflow by a comprehensive surgical landscape guidance system (COMPASS). Real-time tracking of a laparoscopic camera used in minimally-invasive...


September 2021

Endoskopische Vermessung von Nasenseptumdefekten

Jean-Claude Rosenthal, Peter Eisert, Anna Hilsmann, Eric Wisotzky, Florian C. Uecker, Carsten Matuschek, Melanie Hobl

In the context of otorhinolaryngologic surgery, we present a gentle approach to treating NSP with a new image-based, contactless, and radiation-free measurement method using a 3D endoscope. The method relies on image information only and makes...


September 2021

Formation of Titanium Nitride, Titanium Carbide and Silicon Carbide Surfaces by High Power Femtosecond Laser Treatment

R. Fedorov, Wolfgang Schade, Karl Wöbbeking, Mingji Li, Eike Hübner, Felix Lederle, V. Olszok

Surface treatment with femtosecond laser pulses at high repetition rates in the presence of gaseous sources for nitrogen and carbon leads to the formation of stable coatings with nitrides and carbides. High power femtosecond laser setups fill the...


September 2021

Feature Focus: Towards Explainable and Transparent Deep Face Morphing Attack Detectors

Clemens Peter Seibold, Peter Eisert, Anna Hilsmann

In this paper, we present Feature Focus, a new transparent face morphing detector based on a modified VGG-A architecture and an additional feature shaping loss function, as well as Focused Layer-wise Relevance Propagation (FLRP), an extension of...


September 2021

An Efficient Multi-Link Channel Model for LiFi

Sreelal Maravanchery Mana, Volker Jungnickel, Jonas Hilt, Peter Hellwig, Sepideh Mohammadi Kouhini, Kerolos Gabra Kamel Gabra

The emergence of LiFi for indoor communications opens up new possibilities for wireless services in crowded multiuser scenarios. The deployment of LiFi in indoor scenarios is challenging due to the line-of-sight (LOS) blockage as well as...


August 2021

Deep Convolutional Neural Network for Network-wide QoT Estimation

Pooyan Safari, Johannes Fischer, Mohammad Behnam Shariati, Geronimo Bergk

We propose a novel Deep Convolutional Neural Network formulation for network-wide QoT classification tasks and show its effectiveness for networks with significant topological differences. Our formulation achieves ~99% accuracy on large and...


August 2021

S-Band Transmission with Off-the-Shelf C-Band Components Enabled by Nonlinear Predistortion based on Coherent System Identification

Robert Emmerich, Colja Schubert, Carsten Schmidt-Langhorst, Ronald Freund, Robert Elschner, Isaac Sackey, Mustafa Sezer Erkilinc, Matheus Ribeiro Sena

Nonlinear Predistortion based on Coherent System Identification Text: In order to cope with the rapid traffic growth and as well reducing the cost-per-bit, reuse of the legacy optical fiber infrastructure is one of the main objectives for...


August 2021

Benefits of MIMO Mode Switching, Angular Diversity and Multiuser Multiplexing for LiFi

Sepideh Mohammadi Kouhini, Volker Jungnickel, Ronald Freund, Dominic Schulz, Peter Hellwig

We report on the first real-time experiments with distributed MIMO and multiple users for LiFi. MIMO mode switching and angular diversity are beneficial for robust-ness. Multiuser multiplexing helps in scenarios where users have complementary...


August 2021

Distributed MIMO Experiment Using LiFi Over Plastic Optical Fiber

Sepideh Mohammadi Kouhini, Volker Jungnickel, Ronald Freund, Sreelal Maravanchery Mana, Sepideh Mohammadi Kouhini, Jean-Paul Linnartz , Carina Ribeiro Barbio Corrêa, Eduward Tangdiongga, Thiago Cunha, Xiong Den

This  paper  shows  the  feasibility  of  a  networked LiFi  system  using  a  distributed  multiple-input  multiple-output(MIMO)  link  for  optical ...


August 2021

A Latency-Aware Real-Time Video Surveillance Demo: Network Slicing for Improving Public Safety

Mohammad Behnam Shariati, Johannes Fischer, R. Nejabati, Jörg-Peter Elbers, Dimitra Simeonidou, R. Casellas, O. González de Dios, A. Autenrieth, Luis Velasco, Ralf-Peter Braun, Annika Dochhan, Bodo Lent, J.J. Pedreno-Manresa, A. S. Muqaddas, L. L. Canto, J. E. Lopez de Vergara, S. López-Buedo, F.J. Moreno, P. Pavón, S. Patri, A. Giorgetti, A. Sgambelluri, F. Cugini

We report the automated deployment of 5G services across a latency-aware, semi-disaggregated, and virtualized metro network. We summarize the key findings in a detailed analysis of end-to-end latency, ! service setup time, and soft-failure...


August 2021

LiFi Positioning for Industry 4.0

Sepideh Mohammadi Kouhini, Volker Jungnickel, Ronald Freund, Christoph Kottke, Ziyan Ma, Marcel Müller, Daniel Behnke, Marcos Martinez Vazquez, Jean-Paul Linnartz

Precise  position  information  is  considered  as  the main  enabler  for  the  implementation  of  smart  manufacturing systems  in  Industry  4.0.  In ...


August 2021

Inter-Operator Machine Learning Model Trading over Acumos AI Federated Marketplace

Mohammad Behnam Shariati, Johannes Fischer, Pooyan Safari, Geronimo Bergk, Felix Immanuel Oertel

We demonstrate the development of a QoT classifier over an autonomous machine-learning pipeline, the trading of the classifier over a federated marketplace, and eventually its deployment in the customer’s network as a cloud-native...


August 2021

Explain and Improve: LRP-Inference Fine Tuning for Image Captioning Models

Jiamei Sun, Wojciech Samek, Alexander Binder, Sebastian Lapuschkin

This paper analyzes the predictions of image captioning models with attention mechanisms beyond visualizing the attention itself. We compare the interpretability of attention heatmaps systematically against the explanations. We demonstrate that...


August 2021

FantastIC4: A Hardware-Software Co-Design Approach for Efficiently Running 4bit-Compact Multilayer Perceptrons

Simon Wiedemann, Thomas Wiegand, Wojciech Samek, Friedel Gerfers, Daniel Becking, Suhas Shivapakashy, Pablo Wiedemann

With the growing demand for deploying Deep Learning models to the “edge”, it is paramount to develop techniques that allow to execute models within very tight and limited resource constraints. In this work we propose a software-hardware...


August 2021

Clustered Federated Learning: Model-Agnostic Distributed Multi-Task Optimization under Privacy Constraints

Felix Sattler, Klaus-Robert Müller, Wojciech Samek

Federated learning (FL) is the most widely adopted framework for collaborative training of deep learning models under privacy constraints. Albeit its popularity, it has been observed that FL yields suboptimal results if the clients’ data...


August 2021

Enabling S-C-L-Band Systems with Standard C-Band Modulator and Coherent Receiver using Nonlinear Predistortion

Robert Emmerich, Colja Schubert, Carsten Schmidt-Langhorst, Ronald Freund, Robert Elschner, Isaac Sackey, Matheus Ribeiro Sena

To counteract the forthcoming capacity crunch in optical networks by increasing the throughput over already existing fiber infrastructures, innovative approaches are required. Multiband systems are an interesting approach to address this issue....


August 2021

Zero on Shape: A Generic 2D-3D Instance Similarity Metric learned from Synthetic Data

Maciej Janik, Peter Eisert, Anna Hilsmann, Niklas Gard

We present a network architecture which compares RGB images and untextured 3D models by the similarity of the represented shape. Our system is optimised for Zero-Shot retrieval, meaning it can recognise shapes never shown in training



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