Forschung an der MST

SMART FIBER COMMUNICATION USING DEEP LEARNING AND DIGITAL HOLOGRAPHY
Prof. Juergen Czarske, Qian Zhang, Dennis Pohle

In the era of Big Data, more and more sensitive data are transmitted on the Internet.
To meet the growing demand for data transmission and especially ensure data security, how to improve transmission capacity and guarantee data security has become a core issue in the field of communication. Quantum Key Distribution (QKD) is a quantum communication protocol that has been developed for distributing secure public keys among remote parties, is a technology that can actually address communication security problems. The Paradigm Shift is to exploit the physical layer for data security instead of using electronic coding (RSA). Measurement technology plays a key role, since thescattering of light in multimode fibers is explored and thus a physical key is provided for the legitimate receiver. The better the measurement can be made, the higher the data security of multimode fibers. At the Czarske Lab/Chair MST of TU Dresden we are working on these advances with innovative approaches of digital holography and deep learning.

A single conventional single-mode fiber is usually used as the medium for classical communication. Through technologies such as time division multiplexing, wavelength division multiplexing, and polarization multiplexing, the single-mode fiber has approached its physical transmission limit. Compared with SMF networks, networks using space-division multiplexing (SDM) or mode-division multiplexing are several orders of magnitude better than all previous standards. Few-mode fibers and multi-mode fibers are expected to play an important role in future data networks.

Chair MST/Czarske Lab is dedicated to classical and quantum communications based on novel laser metrology. We have demonstrated the feasibility of enhancing information security using physical layer security in multi-mode fibers, which can be applied in high-capacity SDM networks of the future. We are exploring the deployment of few-mode fibers in QKD system by leveraging various technologies, such as wavefront shaping, holography, and artificial intelligence, to improve the key transmission rate and establish a MIMO (Multiple Input Multiple Output) key distribution system.

The team members have won several prizes, including:

• Juergen Czarske (2022 SPIE Chandra S Vikram Award, San Diego, US/inaugural 2020 IEEE Laser Instrumentation Award),
• Stefan Rothe (2023 PhD Prize, 3 000 Euro),
• Qian Zhang (2021 Prize for the best Master Thesis, Gisela and Erwin Sick Foundation, Freiburg),
• Dennis Pohle (2022 Prize for applied optics, DGaO, Pforzheim), Anna-Lena Geppert (2022 Theodore Maiman Scholarship for best Bachelor Thesis, WLT, 2 000 Euro),
• David Krause (2023 Master Thesis Prize), etc.

Several open positions are available. Please apply for Postdoc and PhD positions.

Projects include:

• DFG Physical Layer Security of Multimode Optical Fiber Transmission Systems: Partners: Technische Universität Braunschweig
•  BMBF 6G-life:
  Short introduction + website  https://6g-life.de/
  Partners: Technische Universität München and University College London
•  BMBF QUIET
  Short introduction from BMBF + website  https://www.forschung-it-sicherheit-kommunikationssysteme.de/projekte/quiet
  Partners: Deutsche Telekom AG, IFW Dresden, Technische Universität München

Papers include:

• Securing Data in Multimode Fibers by Exploiting Mode-Dependent Light Propagation Effects  https://spj.science.org/doi/full/10.34133/research.0065
• Physical layer security in multimode fiber optical networks  https://www.nature.com/articles/s41598-020-59625-9
• Learning the matrix of few-mode fibers for high-fidelity spatial mode transmission https://aip.scitation.org/doi/full/10.1063/5.0088605
• Surveillance of few-mode fiber-communication channels with a single hidden layer neural network  https://opg.optica.org/ol/fulltext.cfm?uri=ol-47-5-1275&id=469958
  Date: April 2023

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The MST is modeling, implementing and applying novel measurement and sensor systems. Five areas of the high-tech strategy of the Federal Government of Germany (communications, security, mobility, energy and health) require advances in instrumentation and sensor techniques. Current issues in research and teaching of the laboratory are biophotonics (health), process engineering and production (energy), aerospace (mobility), cryptography, automation and control (security), and information system technique (communication).

In the following, some examples of the interdisciplinary research of the MST are given.

• Renewable Energy Technology I: Modell analysis for magnetically controlled crystal growth process is accomplished in cooperation with industrial partners. One goal is to increase the efficiency of solar cells. The MST is developing ultrasound array techniques with real-time streaming processing, which allow long-term investigations of transient processes.
• Renewable Energy Technology II: For revealing the flows in fuel cells, a laser velocity profile sensor is used, which requires only one optical access and enables micron resolution. For fuel cell stacks the distribution problem of reagents can be understood by this technique.
• Environmental protection I: Bias flow liners enable the reduction of noise of aircraft engines. However, the interaction of sound and flow is very complex and not completely understood yet. The MST has developed a novel laser technique for simultaneous sound and flow velocity measurements with high dynamics, which enables to investigate strategies for noise damping of airplanes.
• Environmental Protection II: To reduce the consumption of fossil fuels and the gas emissions during flight operations, innovative propulsion concepts are studied. Lean combustions enable on the one hand lower fuel consumption, but on the other hand they can exhibit a high instability. The MST investigates these processes using a novel camera-based measurement technique.
• Biomedical I: Electrically tunable liquid lenses enable fast scanning processes without mechanical movements. The MST has realized three-dimensional microscopes by employing adaptive lenses. The thyroid development of transgenic zebra fishes is investigated in dependency of environmental influences.
• Biomedicine II: Optogenetics introduces fundamentally novel ways to study neurodegenerative diseases such as Alzheimer's disease, epilepsy and Parkinson's disease. The MST works on the development of digital adaptive laser systems for the tar-geted stimulation and detection of physiological processes in model organisms. The generation of spatially and temporally variable light patterns in deep tissue plays a key role.
• Biomedicine III: With dispersive elements (VIPA: virtually imaged phased array) and low-noise sCMOS cameras the fre-quency shift of Brillouin scattering (phonon-photon interaction) can be measured with high resolution. Brillouin microscopy allows contactless, spatially resolved and rapid diagnosis of the mechanical properties of biological tissue. Early detection of cancer becomes possible.