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While the world eagerly waits to use the full potential of 5G cellular technology, researchers are now already working on technologies for the next generation of wireless data transmission – “6G”. The sixth generation update is expected to have far higher transmission rates and shorter delays than 5G, and also an increased device density, with artificial intelligence (AI) playing an important role. But on the way towards the sixth generation cellular network, many challenges have to be mastered regarding both individual components and their interaction.Future wireless data networks will have to reach higher transmission rates and shorter delays, while supplying an increasing number of end devices. For this purpose, network structures consisting of many small radio cells will be required. To connect these cells, high-performance transmission lines at high frequencies up to the terahertz range will be needed. Moreover, seamless connection to glass fiber networks must be ensured, if possible. Addressing the challenge, researchers at the Karlsruhe Institute of Technology (KIT), as published in the journal Nature Photonics, have used ultra-rapid electro-optical modulators to convert terahertz data signals into optical signals.The next generation of wireless networks will consist of a number of small radio cells to quickly and efficiently transmit large data volumes. These cells will be connected by transmission lines, which can handle tens or even hundreds of gigabits per second per link. The necessary frequencies are in the terahertz range, i.e. between microwaves and infrared radiation in the electromagnetic spectrum. In addition, wireless transmission paths have to be seamlessly connected to glass fiber networks. In this way, the advantages of both technologies, i.e. high capacity and reliability as well as mobility and flexibility, will be combined.Scientists of the KIT Institutes of Photonics and Quantum Electronics (IPQ), Microstructure Technology (IMT), and Radio Frequency Engineering and Electronics (IHE) and the Fraunhofer Institute for Applied Solid State Physics IAF, Freiburg, have now developed a promising approach to converting data streams between the terahertz and optical domains. As reported in Nature Photonics, they use ultra-rapid electro-optical modulators to directly convert a terahertz data signal into an optical signal and to directly couple the receiver antenna to a glass fiber.In their experiment, the scientists selected a carrier frequency of about 0.29 THz and reached a transmission rate of 50 Gbit/s. According to Professor Christian Koos, Head of IPQ and Member of the Board of Directors of IMT, the modulator is based on a plasmonic nanostructure and has a bandwidth of more than 0.36 THz. The results reveal the great potential of nano-photonic components for ultra-rapid signal processing. The concept demonstrated by the researchers will considerably reduce the technical complexity of future radio base stations and enable terahertz connections with very high data rates – several hundred gigabits per second are feasible.Click here to read the published paper.