Recent publications

May 2025

Inter-hospital transferability of AI: A case study on phase recognition in cholecystectomy

Lasse Renz-Kiefel, Peter Eisert, Anna Hilsmann, Eric Wisotzky, sebastian Lünse, Rene Mantke

Identifying surgical phases is a crucial component of surgical workflow analysis, facilitating the automated evaluation of surgical procedures’ performance and efficiency. A significant challenge in developing neural networks for surgical phase...


May 2025

Realtime-Rendering of Dynamic Scenes with Neural Radiance Fields

Kilian Leonard Krause, Peter Eisert, Anna Hilsmann, Wieland Morgenstern

This paper addresses the challenge of real-time rendering of dynamic 3D scenes using Instant Neural Graphics Primitives (iNGP), training a separate radiance field for each frame. To enable interactive VR playback, efficient data storage and...


May 2025

Experimental demonstration of robust spatial-diversity combining for coherent free-space optical transmission

Abraham Johst, Lutz Molle, Michael Rohde, Ronald Freund, Markus Nölle, Nicolas Perlot

Spatial-diversity schemes are applied to improve signal quality of coherent free-space optical transmission systems with uncorrelated phase noise. We compare the performance of conventional schemes (MRC, SDC) to a newly proposed one (X-MRC).


May 2025

Space-Division Multiplexed Transmission from the Lab to the Field

C. Antonelli, A. Mecozzi, Colja Schubert, L.K. Oxenløwe, A. Carena, Robert Emmerich, Georg Rademacher, Nicolas Fontaine, Giammarco Di Sciullo, Andrea Marotta, Fabio Graziosi, Takuji Nagashima, Alberto Gatto, Paola Parolari, Pierre Sillard, Roland Ryf, Lauren Dallachiesa, R.S. Luis, D. A. Shaji, D. Ri-bezzo, M. Mazur, T. Nakanishi, D. Bacco, A. Zavatta, M. Zahidy, D. Orsuti, M. Fasano, P. Boffi, N. Sambo, A. Nespola, S. Guerrier, C. Dorize, J. Renaudier, N. Hoghooghi, F. Quinlan, Qi Wu

Researchers from the University of L’Aquila, NICT, Finisar, Prysmian, Nokia Bell Lab and Fraunhofer HHI Space-Division Multiplexed Transmission technologies from the Lab to the Field and present a summary for their work in this invited...


May 2025

Timebin-Phase BB84 Quantum Key Distribution Using Telecom-Wavelength Fiber-Coupled SPADs

Jan Krause, Patrick Runge, Martin Schell, Ronald Freund, Nino Walenta, Pascal Rustige

Single-photon avalanche detectors (SPADs), which operate without cryogenic cooling, are a core component for practical QKD systems. We demonstrate 13-hour continuous key generation with our timebin-phase BB84 QKD system using our InGaAs/InP SPAD,...


May 2025

A Flexible Real-Time Quantum Key Distribution System for Fiber and Free-Space Links

Jan Krause, Ronald Freund, Jonas Hilt, Nino Walenta

To enable QKD in various scenarios, we developed a 625 MHz real-time autonomous timebin-phase QKD system with custom clock synchronization. We demonstrate the system’s performance and robustness under unstable link conditions, a variety of fiber...


May 2025

Single-Carrier 2.56 Tb/s (3-mode x 128-GBd x DP-16QAM) Transmission over a 53.7 km Few Mode Fiber

Nicolas Braig-Christophersen, Colja Schubert, Carsten Schmidt-Langhorst, Ronald Freund, Robert Emmerich, Fabian Chowanek, Georg Rademacher, Hideaki Furukawa, Aymeric Arnould, Benjamin J. Puttnam, Kazuhiko Aikawa, Juan Carlos Alvarado Zacarias, Rodrigo Amezuca-Correa, Ruby S. B. Ospina

We investigate high-symbol rate SDM transmission using 16 to 128 GBd QPSK, 16-QAM and 64-QAM modulation over a 3-mode fiber. An aggregated net rate of 2.56 Tb/s was obtained after 54 km transmission using 128 GBd 16-QAM signals.


May 2025

Clock offset synchronization with sublinear complexity for quantum key distribution on low-level hardware

Jan Krause, Ronald Freund, Jonas Hilt, Nino Walenta

We introduce iQSync, a clock-offset recovery method for quantum key distribution. iQSync achieves sub-linear computational complexity, allowing for the implementation on low-level hardware. We demonstrate the method for channel attenuations...


May 2025

Monolithic InP Ring Resonator based Laser with 40 kHz Linewidth and 40 nm Tuning Range

Hendrik Boerma, Patrick Runge, Martin Schell, Arbnor Berisha, Daniel Haubenreißer

A narrow linewidth tunable laser based on ring resonators is presented. It uses low loss passive waveguides implemented in a monolithic InP photonic integrated circuit. The laser can be tuned over a wavelength range from 1559 nm to 1602 nm. The...


April 2025

3DGS.zip: A survey on 3D Gaussian Splatting Compression Methods

Milena Teresa Bagdasarian, Mario Goldenbaum, Peter Eisert, Anna Hilsmann, Wieland Morgenstern, Florian Tim Barthel, Paul Knoll, Yi-Hsin Li

3D Gaussian Splatting (3DGS) is a powerful technique for real-time radiance field rendering but is limited by its high storage and memory requirements. This survey provides the first comprehensive analysis of existing compression and compaction...


April 2025

Intraoperative measurements in stapedotomy using 3D stereo imaging for optimal prosthesis length selection

Eric Wisotzky, Peter Eisert, Anna Hilsmann, Sebastian Schraven, Robert Mlynski, Felix Lausch, Linus Kienle, Sahra von Bonn-Ytrehus

This study introduces a novel approach for precise, radiation-free intraoperative measurements using 3D stereoscopic imaging integrated into a digital surgical microscope for stapedotomy. By optimizing the calibration of stereoscopic zoom-focus...


April 2025

Kernel-Based Signal Processing for Simultaneous Transmit-Receive Systems

Mohammad Hossein Attar, Slawomir Stanczak, Ramez Askar

We address digital self-interference cancellation (SIC) in simultaneous transmit-receive systems using data-driven approaches. We propose kernel-based learning methods -- adaptive projected subgradient method (APSM) and support vector regression...


April 2025

Record length of 2000km weakly-coupled 7-core MCF produced from a single large-scale MCF preform

Sarah Cwalina, Kai Habel, Tobias Tiess, Michael Lorenz, Jong-Won Lee, Maximilian Schmitt, Jimmy E. Beavers, Nicolaj L. Andersen, Andreas C. Samson, Frederik N. Andersen, Qiulin Ma, Martin Böttcher, Kay  Schuster

We present the design and fabrication of more than 2000 km of a 7-core multi-core fiber (MCF) drawn from a single large-scale MCF preform. The fiber was fabricated without any online fiber breaks and exhibits axially excellent geometrical...


April 2025

Designing Citizen Science tools towards increased awareness and participatory policy making for air quality: The Case of COMPAIR

Pavel Kogut, Oliver Schreer, Sylvain Renault, Lieven Raes, Burcu Celikkol, Susie Ruston McAleer, Gert Vervaet, Christos Alexopoulos

The EU-funded project COMPAIR designed advanced monitoring and simulation tools that aggregate data from multiple sources to provide a well-rounded view of air pollution and related challenges e.g. traffic, waste management, energy use. Built-in...


April 2025

Artificial Neural Network With Photonic Reservoir for Multiclass Modulation Format Identification

Guillermo von Hünefeld, Colja Schubert, Ronald Freund, Johannes K. Fischer, Pooyan Safari, Rijil Thomas, Enes Seker, Stephan Suckow, Max Lemme, David Stahl, Peter Bienstman, Mahdi Kaveh, Mahtab Aghaeipour Kolyani, Joseph Hopfmüller

We successfully achieved MFI using a neuromorphic PIC with a photonic reservoir and digital readout, both in a laboratory environment and with commercial network equipment.


April 2025

Resolution and Speed Trade-offs in FMCW LiDAR with MEMS Mirror Scanning and Advanced Signal Processing

Sarah Cwalina, Volker Jungnickel, Patrick Runge, Norman Laske, Avinash Nittur Ramesh, Maria A. Gonzalez-Huici

We address system trade-offs, e.g. between resolution and speed of a coherent scanning LiDAR. We analyze the performance of our real-time FMCW LiDAR prototype with a high-quantumefficiency coherent receiver, two-dimensional...


April 2025

Joint power control, beamforming, and sleep-mode selection for energy-efficient cell-free networks using surrogate machine learning models

Ricky Ooi, Slawomir Stanczak, Renato L. G. Cavalcante, Lorenzo Miretti, Rouaa Diab

In cell-free networks, system throughput is enhanced by allowing more than one access point (AP) to serve each user, which may lead to high energy consumption. To circumvent this, this paper presents a surrogate optimization technique using...


April 2025

Global or local modeling for XGBoost in geospatial studies upon simulated data and German COVID-19 infection forecasting

Ximeng Cheng, Jackie Ma

This research compares the local- and global modeling ways of XGBoost in the geospatial studies. Two experiments based on simulation data and German COVID-19 infection data were conducted to compare the two modeling ways from multiple aspects....


April 2025

SPNeRF: Open Vocabulary 3D Neural Scene Segmentation with Superpoints

Weiwen Hu, Oliver Schreer, Peter Eisert, Ingo Feldmann, Marcus Zepp, Niccolo Parodi

We introduce SPNerf, a NeRF based zero-shot 3D segmentation approach that leverages geometric priors. We integrate geometric primitives derived from 3D scene into NeRF training to produce primitive-wise CLIP features, avoiding the ambiguity of...


April 2025

3D photonic integrated interposer enabling connectivity between multicore fibers and photonic integrated circuits

Madeleine Weigel, Norbert Keil, Martin Schell, Moritz Kleinert, Crispin Zawadzki, David de Felipe Mesquida, Martin Kresse, Tianwen Qian, Jakob Reck, Klara Mihov, Philipp Winklhofer, Lea Flach

A novel 3D photonic integrated interposer is developed for coupling the different layers of Multi-core-fiber (MCF) cores with arrays of conventional 2D electro-absorption modulated lasers (EMLs) and photodetectors (PDs). The 3D photonic...


April 2025

Next Generation XR Systems-Large Language Models Meet Augmented and Virtual Reality

Muhamamd Zeshan Afzal, Peter Eisert, Anna Hilsmann, SK Aziz Ali, Didier Stricker, Daniel Perez-Marcos, Marco Bianchi, Sonia Crottaz-Herbette, Roberto De Ioris, Eleni Mangina, Mirco Sanguineti, Ander Salaberria, Oier Lopez de Lacalle, Aitor García-Pablos, Montse Cuadros

Extended Reality (XR) is evolving rapidly, offering new paradigms for humancomputer interaction. This position paper argues that integrating Large Language Models (LLMs) with XR systems represents a fundamental shift toward more intelligent,...


March 2025

High-quality deepfakes have a heart!

Clemens Peter Seibold, Peter Eisert, Anna Hilsmann, Eric Wisotzky, Benjamin Kossack, Arian Beckmann

Recent deepfakes preserve subtle heart rate signals, challenging the assumption that rPPG-based detection remains effective. Our study demonstrates that modern deepfake generation techniques encapsulate the heart rate dynamics of source videos,...


March 2025

Adaptive and Temporally Consistent Gaussian Surfels for Multi- view Dynamic Reconstruction

Decai Chen, Oliver Schreer, Peter Eisert, Ingo Feldmann, Anna Hilsmann, Brianne Arielle Oberson

We propose AT-GS, a novel method for reconstructing high-quality dynamic surfaces from multi-view videos through per-frame incremental optimization. To avoid local minima across frames, we introduce a unified and adaptive gradient-aware...


March 2025

Automatic Drywall Analysis for Progress Tracking and Quality Control in Construction

Mariusz Trzeciakiewicz, Peter Eisert, Anna Hilsmann, Niklas Gard, Aleixo Cambeiro Barreiro

This paper presents an automated drywall analysis method for construction progress and quality assessment using on-site cameras. It integrates a deep learning-based segmentation model to detect and classify drywall elements, with a module to...


March 2025

Improving Geometric Consistency for 360-Degree Neural Radiance Fields in Indoor Scenarios

Iryna Repinetska, Peter Eisert, Anna Hilsmann

NeRFs struggle with low-textured areas, causing "floaters" that reduce realism, especially on featureless surfaces. We propose a method for computing dense depth priors for these areas, using a novel depth loss function and patch regularization...


March 2025

Experimental Demonstration of a Correlation-Avoidance CMA for Blind Space-Division Multiplexed MIMO Equalization

Pamir Oezsuna, Colja Schubert, Carsten Schmidt-Langhorst, Ronald Freund, Robert Emmerich, Nicolas Braig-Christophersen, Georg Rademacher, Ruben S. Luis, Aymeric Arnould, Emil Luis Spoiden, Benjamin J. Puttnam, Kazuhiko Aikawa

We demonstrate blind 6x6 adaptive equalization of 32 GBd DP-QPSK 3-mode transmission over a 54 km FMF based on the singularity-free convergence ability of the correlation-avoidance CMA (CA-CMA). The CA-CMA is used for robust pre-convergence in a...


March 2025

7.75 Gbit/s LiFi Transmitter Using High-Power VCSEL Arrays

Malte Hinrichs, Volker Jungnickel, Ronald Freund, Dominic Schulz, Giulio Boniello

We report on a wide-beam LiFi transmitter using multiple VCSEL arrays with digital drivers. We transmit a 3.75 GBd PAM-3 signal at a gross data rate of 5.625 Gbit/s. Single-driver OOK operation yields 7.75 GBd.


March 2025

Data Governance Framework for Telemetry Sharing

Angela Mitrovska, Johannes Fischer, Mohammad Behnam Shariati, Pooyan Safari

We propose a novel solution using the Eclipse Dataspace Components (EDC) Connector to enable regulated and policy-driven telemetry data sharing in telco ecosystems. We present its architecture, several compatible use-cases, and results validating...


March 2025

3D-Printed Dual-Polarized Magneto-Electric Dipole Antenna with Wideband High Isolation for Full-Duplex Applications

Mehmet Ahad Yurtoglu, Ramez Askar

This paper presents a dual-polarized magneto-electric dipole antenna with orthogonal Gamma and inverted-Gamma probes, fabricated via 3D metal printing. It offers a 3-4 GHz impedance bandwidth, with excellent cross-polarization isolation (>50...


March 2025

Analysis of Interaction Mechanisms and Intercomparison of Raytracing Tools for Optimizing THz Simulations

Enes Aksoy, Leszek Raschkowski, Alper Schultze, Mikel Celaya-Echarri, Leyre Azpilicueta, Abdolvakil Fazli

This paper compares different raytracing tools in the sub-THz area, to analyze the weight of several different effects, e.g. reflections, diffractions, scattering or atmospheric attenuation, during raytracing simulations for high frequencies. For...


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