A team of researchers at ETH Zurich has achieved a breakthrough in optical data transmission, developing a plasmonic modulator capable of operating at frequencies beyond one terahertz.
This milestone, reached by Professor Jürg Leuthold’s Photonics and Communications group, significantly surpasses previous limits of 100 to 200 gigahertz – marking a five- to tenfold improvement.
Plasmonic modulators serve as crucial components in high-speed communication, converting electrical signals into optical signals for transmission via optical fibres. Their role is increasingly critical as global data demand accelerates, requiring faster and more efficient signal processing.
Bridging the gap between electronics and optics
With the arrival of 6G mobile networks, which will operate in the terahertz range, the need for seamless electrical-to-optical signal conversion is more pressing than ever. “Data is always initially present in electrical form and nowadays, its transmission always involves optical fibres at some point,” explains Professor Leuthold.
The next generation of mobile communications (6G) will operate in the terahertz range. Its backbone – the cables between the base stations – relies on optical fibre technology. “Our modulator allows radio signals and other electrical signals to be converted into optical signals directly and therefore efficiently,” says Yannik Horst, who worked on the component during his doctoral thesis.
Beyond telecommunications: expanding applications
While terahertz signals can already be transmitted via optical fibres, existing methods require multiple expensive components, leading to high energy consumption and limited accuracy. The new ETH Zurich modulator streamlines this process, offering direct conversion across a vast frequency range – from 10 megahertz to 1.14 terahertz.
The technology has potential applications well beyond telecommunications. In medicine, it could improve imaging techniques, while in security, it could enhance baggage scanning systems. Spectroscopy for material analysis, high-performance computing, and radar technology could also benefit from the increased precision and efficiency.
From research to real-world deployment
The modulator itself is a nanostructure composed of various materials, including gold, leveraging interactions between light and free electrons. Developed at ETH Zurich, it is being commercialised by Polariton Technologies, a spin-off from Leuthold’s group. The company is now working to bring this innovation to market, positioning it as a key enabler for future data transmission and measurement technologies.
Image: The modulator (in gold) transfers the information from an electrical wave to an optical one. (Credit: Johannes Grewer/Polariton Technologies)
