Recent publications

November 2025

Ad-hoc hybrid-heterogeneous metropolitan-range quantum key distribution network

Jan Krause, et al., Matthias Goy

This paper presents the development and implementation of a versatile ad-hoc metropolitan-range quantum key distribution (QKD) network. The approach presented integrates various types of physical channels and QKD protocols, and a mix of trusted...


November 2025

Split-Inference Architecture for Device-Centric Radio Sensing in a Networked Robotics Scenario

Mehdi Heshmati, Slawomir Stanczak, Michael Peter, Ramez Askar, Zoran Utkovski, Sven Wittig, Yuzhen Ke, Kenan Turbic

An architecture for neuromorphic device-edge co-inference, with application to radio sensing for environment mapping in networked robotics scenarios. The developed demonstration setup integrates a radar sensor, radar preprocessing unit and...


November 2025

Robust and Efficient Kernel-Based Digital Self-Interference Cancellation Using a Priori Knowledge in Full-Duplex Transceivers

Mohammad Hossein Attar, Slawomir Stanczak, Ramez Askar, Jochen Fink

An enhanced digital self-interference cancellation technique for in-band full-duplex (FD) wireless communications, focusing on overcoming challenges from nonlinear distortions. The method uses a kernelized adaptive projected subgradient method...


November 2025

Real-Time Demonstration of Integrated Sensing and Communication in the Sub-Terahertz D-Band

Sven Wittig, Slawomir Stanczak, Michael Peter, Ramez Askar, Rodrigo Hernangómez

Real-time demonstration of an ultra-broadband (4 GHz) integrated sensing and communications (ISAC) system operating at 160 GHz in the upper D-band. The demonstration showcased quasi-monostatic sensing and a 4.9 Gbit/s communication link,...


November 2025

Intraoperative perfusion assessment by continuous, low-latency hyperspectral light-field imaging: development, methodology, and clinical application

Stefan Kray, Anna Hilsmann, Eric Wisotzky, Andreas Schmid, Moritz Gerlich, Sebastian Apweiler, Thomas Greiner, Werner Kneist

This study presents a hyperspectral light field system for intraoperative tissue oxygen saturation (????????2) analysis and visualization. We present a correlation method for determining SO2 saturation with low computational demands. We...


November 2025

Sub-THz MIMO Hybrid Beamforming: D-Band Dual-Channel Analog Beamforming Front-Ends Prototyping

Ramez Askar, Thomas Haustein, Michael Peter, Jaehoon Chung, Axel Tessmann, Laurenz John, Jongpil Lee, Mehmet Ahad Yurtoglu, Vitor Carvalho De Almeida, Arnulf Leuther, Kim Woochan, Chulkyu Mun, Yonghak Suh

Design and implementation of novel D-band (sub-THz) dual-channel (MIMO hybrid) beamforming wireless front-ends operating between 150 and 170 GHz. The system utilizes analog beamforming networks with two 16×16 microstrip Rotman lenses and dual...


November 2025

Evaluation of a WR6.5 Rotary Joint with two 3D-printed TE01 Mode Transducers

Mathis Schmieder, Wilhelm Keusgen, Michael Peter, Sven Wittig, Steffen August Sigwart

This paper explores a WR6.5 rotary joint based on two 3D-printed mode transducers. Tests from 140 to 170 GHz show about 2 dB of insertion loss across a 16 GHz usable band (145-161 GHz) and less than 15 degree of phase variation, validating 3D...


November 2025

Dual-Beam Planar D-Band Antenna Array: Filtering Patch Antennas and Dielectric Lens

Vitor Carvalho De Almeida, Thomas Haustein, Wilhelm Keusgen, Michael Peter, Ramez Askar, Jaehoon Chung, Laurenz John, Yonghak Suh, Jongpil Lee, Mehmet Ahad Yurtoglu, Arnulf Leuther, Kim Woochan, Chulkyu Mun, Kim Jeongin

A hybrid analog beamforming at D-band is demonstrated by integration between an antenna array and a dielectric lens. The beam is collimated on one plane by the antenna array, and on the other by the elliptical lens profile. The antenna element is...


November 2025

15 GHz Independently Controllable Dual-Polarized 2-Bit Reconfigurable Intelligent Surface

Mehmet Ahad Yurtoglu, Wilhelm Keusgen, Michael Peter, Ramez Askar, Mathis Schmieder, Sven Wittig

Experience next-generation reconfigurable intelligent surfaces with a novel dual-polarized 2-bit RIS unit cell offering exceptional 55 dB cross-polarization isolation and 400 MHz bandwidth at 15 GHz. Featuring varactor-loaded bowtie elements and...


November 2025

Experimental Characterization of Photodiode Transmitters for Probabilistically Shaped High-Speed THz Wireless Transmission

In-Ho Baek, Martin Schell, Colja Schubert, Ronald Freund, Robert Elschner, Simon Nellen, Robert Kohlhaas, Oliver Stiewe, Jonas Gläsel, Garrit William Johannes Schwanke, Trung T. Tran

In this paper, we present an experimental investigation of two distinct THz transmitter architectures. While Terahertz (THz) wireless communication is key for 6G networks, a systematic performance comparison between different photonic-generated...


November 2025

CGS-GAN: 3D Consistent Gaussian Splatting GANs for High Resolution Human Head Synthesis

Florian Tim Barthel, Peter Eisert, Anna Hilsmann, Wieland Morgenstern, Paul Hinzer

CGS-GAN enables, for the first time, stable, high-quality, and 3D-consistent head synthesis in 3D Gaussian Splatting GANs—without the view-conditioning that previously caused identity drift and inconsistencies. Through targeted multi-view...


November 2025

Hardware realization of neuromorphic computing with a 4–port photonic reservoir for modulation format identification

Enes Seker, Colja Schubert, Ronald Freund, Isaac Sackey, Gregor Ronniger, Pooyan Safari, Guillermo von Hünefeld, Rijil Thomas, Stephan Suckow, Max Lemme, David Stahl, Mahdi Kaveh, Johannes Karl Fischer

We make a deep dive into the fabrication and testing of a photonic reservoir with digital readout. The developed neural network was tested for the identification of modulation formats at 32 Gbaud transmission rates, where it achieved a near-100%...


October 2025

Real-time Fusion of Stereo Vision and Hyperspectral Imaging for Objective Decision Support during Surgery

Eric Wisotzky, Peter Eisert, Anna Hilsmann, Brigitta Globke, Michael Knoke, Jost Triller

We present a real-time stereo hyperspectral imaging system that combines 3D reconstruction with spectral tissue analysis, enabling live visualization of oxygenation and tissue composition during surgery.


October 2025

Live Demonstration of Modulation Format Identification Using a Photonic Neural Network

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

We demonstrate modulation format identification on a micro ROADM ring using a photonic neural network with low-speed photodiodes.


October 2025

Design and Validation of a Time Domain Correlation based Channel Sounder up to 500 GHz

Alper Schultze, Wilhelm Keusgen, Michael Peter, Ramez Askar, Mathis Schmieder, Sven Wittig, Anton Dilg

In this paper, we introduce a novel time domain correlation based channel sounder that operates at 485 GHz.


October 2025

Agile Sub-Terahertz to Terahertz Broadband Time-Domain Photonic Channel Sounder

Ramez Askar, Mario Goldenbaum, Wilhelm Keusgen, Michael Peter, Colja Schubert, Ronald Freund, Robert Elschner, Taro Eichler, Shahram Keyvaninia, Robert Kohlhaas, Oliver Stiewe, Milan Deumer, Alper Schultze, Garrit William Johannes Schwanke, Nico Vieweg, Thomas Puppe, Sebastian Müller, Albrecht Neudecker

This paper presents the design and implementation of an agile sub-terahertz (sub-THz) broadband time-domain photonic channel sounder, capable of characterizing wireless propagation channels within the 100 GHz to 500 GHz frequency range.


October 2025

RIPE: Reinforcement Learning on Unlabeled Image Pairs for Robust Keypoint Extraction

Johannes Wolf Künzel, Peter Eisert, Anna Hilsmann

We introduce RIPE, an innovative reinforcement learning-based framework for weakly-supervised training of a keypoint extractor that excels in both detection and description tasks. In contrast to conventional training regimes that depend heavily...


October 2025

Waveform Design for Simultaneous MIMO Radar Sensing and Multi-User Communication

Berkan Kilic, Slawomir Stanczak, Kenan Turbic

This work introduces a two-stage waveform design framework for multi-antenna integrated sensing and communication systems. By optimizing radar beampatterns and communication signals under practical constraints, the proposed method achieves...


October 2025

Digital Post-Distortion Architectures for Nonlinear Power Amplifiers: Volterra and Kernel Methods

Daniel Schäufele, Slawomir Stanczak, Renato L. G. Cavalcante, Jochen Fink

In modern 5G UEs, the PA consumes large amounts of power. However, there is a trade-off between power efficiency and nonlinear distortion. This study explores digital post-distortion to address PA nonlinearities at the base station. We take a...


September 2025

Resilience Enhancement of Optical Network-Cloud Ecosystems with Dataspace Framework and Multi-entity Cooperation (Invited)

Sugang Xu, Ronald Freund, Johannes Fischer, Mohammad Behnam Shariati, Pooyan Safari, Angela Mitrovska, Hideaki Furukawa, Subhadeep Sahoo, Yusuke Hirota, Yuki Yoshida, Kouichi Akahane, Sifat Ferdousi, Massimo Tornatore, Yoshinari Awaji , Biswanath Mukherjee

To enhance the resilience of network-cloud ecosystems, we establish a data governance framework for sharing optical testbed data across organizations and fostering machine learning research of optical networks. We further introduce multientity...


September 2025

D-Band Adaptive Beamforming for 6G Sub-THz Communications: Feasibility and Experimental Results

Sven Wittig, Thomas Haustein, Matthias Mehlhose, Slawomir Stanczak, Michael Peter, Ramez Askar, Mathis Schmieder, Thomas Merkle, Jaehoon Chung, Utku Uçak, Laurenz John, Yonghak Suh, Jongpil Lee, Bersant Gashi, Arnulf Leuther

Making sub-Terahertz frequencies usable in future mobile radio networks such as 6G requires adaptive beamforming techniques. Using newly developed D-band front ends, we present first experimental evidence for the feasibility of this approach.


September 2025

Beampattern Synthesis with a Computationally Efficient Matrix Nearness Approach

Berkan Kilic, Slawomir Stanczak, Martin Kasparick, Kenan Turbic

This work introduces a computationally efficient method for MIMO radar beampattern synthesis through optimized waveform covariance matrix design. The approach directs transmitted power toward target regions, minimizes cross-correlations, and...


September 2025

Linear Phase Beampattern Design with Set-theoretic Methods

Jochen Fink, Slawomir Stanczak, Renato L. G. Cavalcante

This paper investigates the potential to approximate a nonconvex beampattern design problem with constraints in the angular domain via a restriction to a convex subset of the feasible region. Simulations show that that imposing this convex...


September 2025

NOBS: A Data-Sovereign Telemetry and Monitoring Framework for 6G Networks

Aydin Jafari, Mohammad Behnam Shariati, Pooyan Safari, Angela Mitrovska, Mihail Balanici, Johannes Karl Fischer Fischer

In this paper, we present the Network Observability Platform (NOBS), a data-sovereign telemetry and monitoring framework designed to meet the primary needs of multi-vendor packet-optical networks in the Sixth Generation (6G) era. NOBS supports...


September 2025

Data Sovereign LLM-Assisted Automation Platform for Open Optical and Packet Transport Networks

Mohammad Behnam Shariati, Johannes Fischer, Pooyan Safari, Angela Mitrovska, Mihail Balanici, Hussein Zaid, Aydin Jafari

The Open Optical Transport Network (OOPT) architecture, defined by the Telecom Infra Project (TIP), is currently being deployed by major operators. The OOPT ecosystem, with its multi-stakeholder and multi-vendor environment, faces challenges like...


September 2025

Batch-Aware Active Learning for Object Detection

Mykyta Kovalenko, Peter Eisert, Anna Hilsmann, Sebastian Bosse

Active Learning is a powerful way to cut down the time and effort needed to annotate data, but its use in object detection remains underexplored. We introduce a Batch-Aware Active Learning (BAAL) framework that combines uncertainty with diversity...


September 2025

Hybrid Photonic Integrated Circuit for Tunable, Narrow-Linewidth mmWave to sub-THz Signal Generation

Tianwen Qian

We experimentally demonstrate a photonic integrated circuit (PIC) that generates tunable mmWave signals with Hz-level linewidths. Utilizing on-chip optical frequency combs and injection locking, the phase-locked optical signals exhibit beat notes...


August 2025

On the effectiveness of multimodal privileged knowledge distillation in two vision transformer based diagnostic applications

Simon Baur, Jackie Ma, Emilio Dolgener Cantú, Alexandra Benova

Deploying deep learning models in clinical practice often requires leveraging multiple data modalities, such as images, text, and structured data, to achieve robust and trustworthy decisions. However, not all modalities are always available at...


August 2025

Sub-THz Waveguide Band-Pass Filter: Design, Analysis and Fabrication Repeatability

Mehmet Ahad Yurtoglu, Michael Peter, Ramez Askar, Sven Wittig

This work presents high-precision all-metal Chebyshev band-pass filters operating in the Y-band (470?GHz) and D-band (160?GHz), featuring six coupled cavities and 10?GHz bandwidth with 20?dB return loss. CNC milling enables sub-5??m fabrication...


August 2025

An Open Source Digital Twin Framework for O-RAN

Hammad Zafar, Slawomir Stanczak, Martin Kasparick, Ehsan Tohidi

This paper introduces a digital twin framework for O-RAN, designed to support the development and testing of xApps. By leveraging real-time data analysis and simulation, digital twins facilitate network performance optimization and enable a...


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