12704_SCTE_Broadband_Nov2016_COMPLETE_lowres

from the industry

The authors, from the Tokyo Institute of Technology, originally published research exploring the direct intensity modulation and wireless data transmission characteristics of terahertz- oscillating resonant tunnelling (RTD) in 2012. The authors found that while data transmission speeds were considerably faster than the current Wi-Fi standard, the low cut-off frequency of the modulation at just 1.5GHz meant that speed was limited to a maximum 3Gbit/s. Through continued research, the team has now reported that speeds of up to 34Gbit/s can be achieved by reducing the parasitic components of the RTD device which enabled a much higher cut-off frequency of 15GHz. The team also improved performance at room temperature and reduced the device's size, meaning that using THz frequencies in small or mobile devices is now a realistic option. Commenting on the research, Naoto Oshimo, one of the authors of the paper, said: “Using the improved device, an error-free transmission up to a data rate of 22Gbit/s, and a transmission

with a bit error rate less than the forward error correction limit up to 34Gbit/s, was achieved. The device performance is almost sufficient for short-distance wireless communication such as KIOSK downloads, which might be its first application.” Final ranges will be up to 10 metres, allowing for use in home Wi-Fi. The application of the terahertz range for wireless communications has long been explored due to its potential to provide significant bandwidth for very high data transfer. Resonant-Tunnelling-Diodes (RTDs) are good candidates for achieving these frequencies as they have the unusual characteristic that the voltage across them can sometimes go down as current is increased. In a final comment, Oshima said: “Owing to the increase in data traffic, the frequency used has been expanded for obtaining a wider bandwidth. This, we hope, will lead to a proliferation in THz wireless communication technology over the next decade.”

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Vol. 38 No. 4 - November 2016 Issue