Connecting these cells requires radio links that can transmit dozens or even hundreds of gigabits per second on a single channel. Frequencies in the terahertz range are ideal for this purpose. A further task is to seamlessly connect wireless transmission links with fiber optic networks in order to combine the advantages of both technologies – high capacity and reliability with mobility and flexibility.
Scientists at the Karlsruhe Institute of Technology (KIT) of the Fraunhofer Institute for Applied Solid State Physics IAF in Freiburg have developed a promising approach for converting data streams from terahertz transmission to optical transmission. As they report in the journal Nature Photonics, they use ultrafast electro-optical modulators to convert a terahertz data signal directly into an optical signal and thus couple the receiver antenna directly to a glass fibre. In their experiment, the scientists use a carrier frequency of approximately 0.29 THz and achieve a transmission rate of 50 Gbit/s. The signal is then directly coupled to an optical fiber. The modulator is based on a plasmonic nanostructure and has a bandwidth of more than 0.36 terahertz. "The results show the enormous potential of nanophotonic devices for ultrafast signal processing," comments Professor Christian Koos from KIT.
The concept can drastically reduce the technical complexity of future mobile radio base stations and enable terahertz connections with enormously high data rates expected of 6G – several hundred gigabits per second are conceivable.
The researchers have reported on their results in the magazine Nature Photonics.