Plasmonic Modulator Transmits Data in Terahertz Range

A research group from ETH Zurich led by Jürg Leuthold, professor of photonics and communications, has succeeded in transmitting data with a frequency of over a terahertz via a plasmonic modulator. According to the researchers, this is a five- to tenfold improvement compared to what previous modulators could accomplish, which were only able to convert frequencies up to 100 or 200 GHz.
Plasmonic modulators are tiny components that convert electrical signals into optical signals in order to transport them through optical fibers. Terahertz transmitting modulators could be used wherever large volumes of data are transmitted, as a bridge between the electrical world and data transmission using light.

The new modulator is a tiny nanostructure made up of various materials including gold, and makes use of the interaction between light and free electrons within the gold. The technology was developed at ETH Zurich and the device was manufactured by Polariton Technologies, an ETH spin-off that emerged from Leuthold’s group. At present, the company is working to bring the terahertz modulator to market so that it can be widely used in future applications in data transmission and measurement technology.

An artist’s rendering of the gold terahertz modulator developed by ETH Zurich and Polariton Technologies transferring electrical waves to optical ones. Courtesy of Johannes Grewer/Polariton Technologies.

Although the transfer of terahertz signals onto optical fiber is already possible from a technical perspective, it is a laborious process and currently requires several expensive components. The new modulators can convert the signals directly, reducing energy consumption and increasing measurement accuracy. Moreover, different components are currently needed for different frequency ranges. The new modulator can be used with any frequency from 10 MHz to 1.14 THz.

“We cover the entire frequency range with a single component,” said ETH Zurich doctoral student Yannik Horst. “It’s therefore extremely versatile in terms of applications.” One of these applications is 6G mobile communications, which is expected to operate in the terahertz range.

Other potential applications include optical fiber data transmission within and between high-performance computing centers. The components are also of interest for high-performance measurement technology, including imaging techniques in medicine, spectroscopic methods for material analysis, baggage scanners at airports, and radar technology. Some devices of this kind already operate in the terahertz range today.

The research was published in Optica (www.doi.org/10.1364/OPTICA.544016).