Optimization of mode-locked laser diode-based optical frequency combs for applications in THz-Technology, optical metrology and optical communication

• Applicants: Professor Dr.-Ing. Jan C. Balzer; Professor Dr. Martin Hofmann; Dr. Martin Möhrle
• Subject Area: Communication Technology and Networks, High-Frequency Technology and Photonic Systems, Signal Processing and Machine Learning for Information Technology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 565410696

The research project focuses on optimizing optical frequency combs based on mode-locked laser diodes (MLLDs) for applications in terahertz (THz) technology, optical metrology, and optical communication. Due to their compact design and cost efficiency, MLLDs represent a promising alternative to more complex and expensive laser systems, such as Ti:sapphire lasers. However, current MLLDs face limitations in terms of spectral bandwidth, stability, and frequency comb flatness. The project aims to address these challenges by developing innovative MLLD designs with novel materials such as InGaAsP/InGaAlAs multi-quantum-well layers and improving their properties. Objectives include achieving a spectral 3-dB bandwidth of at least 2 THz for single lasers and over 3 THz for 2 synchronized lasers, reducing the RF bandwidth to below 1 kHz, and generating ultrashort pulses close to the Fourier limit. The project is structured into several work packages. Design and Fabrication: Fraunhofer HHI develops new MLLD variants with optimized active layers and hybrid integration. Spectroscopic Analysis: RUB investigates the optical and dynamic properties of MLLDs to drive material and design improvements. Optimization and Synchronization: UDE develops algorithms and feedback mechanisms for laser stabilization and synchronization, such as optical and electrical feedback. Application Validation: The developed MLLDs are tested in key applications such as optical communication, dual-comb spectroscopy, and THz time-domain spectroscopy. By combining the expertise of the project partners, the goal is to advance MLLD technology and establish new benchmarks in fields like optical communication and precision measurement. The project’s outcomes are expected to benefit not only fundamental research but also industrial applications in high-speed data transmission and THz spectroscopy.

• DFG Programme: Research Grants