PLASmonic MODulators and Integrated Circuits for high-speed, energy-efficient, adaptive optical communication Systems (PLASMODICS)

• Applicants: Professor Dr.-Ing. Maurizio Burla; Professor Dr.-Ing. Frank Ellinger
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering ; 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 564649948

Optical communication systems approach key physical limitations. The high modulation voltages required for fast optical modulators, e.g. based on the Mach-Zehnder interferometer approach, restrict the use of further scaled semiconductor technologies needed to follow the roadmaps for electrical driver speeds and lower energy consumptions. With PLASMODICS we propose solutions based on plasmonic modulation allowing voltages which are in the order of ten smaller compared to conventional approaches. However, the key problem is the relatively high loss, which is significantly decreased by plasmonic ring/racetrack modulators (PRIMO/PRAMO) resonating in the off-states simplifying the signalling for the on-states leading to lower losses and enabling very small dimensions, small parasitic capacitances as well as high bandwidths. PLASMODICS aims at triggering a leap innovation by the first co-design of PRIMO/PRAMO together with tailored electrical driver and control circuits enabling bandwidth-adaptivity. We aim at modelling and realizing modulators with losses <2 dB, size <10 µm, bandwidth >100 GHz and modulation voltage <1 V. For this purpose, we study, compare and optimise various fabrication concepts, dimensions, materials and plasmonic waveguides. To our knowledge, we perform the first detailed study of an electrical driver which is tightly co-designed with such a low-voltage PRIMO/PRAMO acting as load. Since the specifications are different to previous works, we will search for answers on various new research questions, e.g. due to the lower modulation and supply voltage, how much can the power be reduced in the driver while achieving enough bandwidth and linearity? At such low supply voltages, how strong is the impact of the transistor saturation voltage and how can circuit concepts be advanced to lower this effect? The goal for the tailored driver is to achieve with <200 mW a record (>3x lower) power consumption at bandwidths >100 GHz. For maximum bandwidths, it is implemented in fastest SiGe BiCMOS technology (IHP SG13G3) with fmax up to 650 GHz. For lower data rates up to 50 Gb/s, a highly-scaled CMOS technology (e.g. 22 nm FDX) is investigated. System saving potentials by adaptivity are evaluated considering varying static and dynamic performance requirements as well as artificial intelligence interfaces. To our knowledge, this is the first study investigating steering concepts for a driver together with a plasmonic modulator enabling a bandwidth-to-dc-power-adaptivity. We explore how much the modulation current and voltage can be controlled to save energy at varying bandwidth requirements while achieving e.g. sufficient extinction and signal to noise ratios and maintaining other important parameters such as signal level and gain. PLASMODICS combines the complementary competences of Burla in photonics and plasmonics, Ellinger in circuit design and Henker in electro-optical system integration and modelling.

• DFG Programme: Research Grants
• Co-Investigator: Dr. Ronny Henker