Robert Emmerich, senior scientist at the Fraunhofer Heinrich Hertz Institute (HHI), completed his doctorate at the Technical University of Berlin in September 2025 with the distinction “summa cum laude.” His dissertation, entitled “Capacity Increase of Deployed Optical Transmission Systems Enabled by Multi-Band Technologies,” addresses the forward-looking question of how existing fiber optic infrastructures can be efficiently expanded through the use of additional optical transmission bands.
Innovative approaches to optical communication
In his thesis, Robert Emmerich analyzed the use of multi-band technologies to increase capacity in optical networks. He experimentally investigated the suitability of commercial C-band components for use in alternative transmission bands such as the L-band and S-band. The goal was to develop a cost-effective expansion strategy that does not require the development of new hardware and flexibly complements existing systems.
The dissertation is divided into three main sections:
- Analysis of system components to identify suitable technologies for multiband systems
- Expansion of metro networks with L-band overlays and investigation of amplification concepts
- System experiments with a complete S-C-L band setup that supports an optical bandwidth of 19.1 THz and enables symbol rates of up to 140 GBaud
The results show that the use of multiband technologies can significantly increase the capacity of existing fiber optic networks while reducing costs.
Many years of expertise at Fraunhofer HHI
Robert Emmerich has been a research associate at Fraunhofer HHI since 2016. He started at the institute as a student assistant in 2012, having previously gained over a decade of industry experience in the field of optical communications. He has contributed to over 78 scientific publications as an author or co-author and presented his research at international conferences.
The doctoral committee consisted of Prof. Dr.-Ing. Lars Zimmermann (TU Berlin, chair), Prof. Dr.-Ing. Ronald Freund, MBA (TU Berlin, Fraunhofer HHI), Prof. Dr.-Ing. Norbert Hanik (TU Munich), and Prof. Dr.-Ing. Stephan Pachnicke (University of Kiel).
Fraunhofer HHI congratulates Robert Emmerich on this outstanding achievement and looks forward to further joint research initiatives in the field of photonic networks and systems.