Optical receiver promises super-fast broadband in every home

Broadband speeds in the UK consistently lag behind other countries, averaging just 36 Mbps. By 2025, speeds up to 100 times faster will be needed to meet the bandwidth demands of technologies such as ultra-high definition video and online gaming.

The receiver is designed to be used in optical access networks, which link internet users with their service providers. It has been developed by researchers at the UCL Optical Networks Group and Cambridge University in a project funded by EPSRC and Huawei Technologies.

The technology, unveiled in a paper in Nature Communications, is designed as a simplified alternative to existing coherent technology, which maximises the capacity of optical fibre links by transmitting data to individual users in dedicated wavelengths of light, according to lead researcher Dr Sezer Erkılınç at UCL.

The coherent receivers are too complex and expensive for use in transmitting data to individual homes, and are their use is therefore limited to the core networks that link different countries and cities.

In coherent technology, the light transmitted along optical fibres is modified and sent across each of two polarisations.

However, by the time the modified signal is received at the user end, this polarisation has typically rotated, meaning it needs to be adjusted using complex optical receiver technology.

Instead, the researchers used a coding technique to transmit the polarised signals, so that the received signal can be recovered independently of any polarisation rotation that occurs along the fibre link. This allows the complexity of the optical receiver to be simplified significantly.

“What we have done is to simply remove some of the optical complexity using digital techniques, while some of the complexity has shifted from the optical domain to the digital domain,” said Erkılınç.

The receiver provides each internet user with a dedicated wavelength, meaning broadband speeds remain constant no matter how many other people are logged on at the same time, said Erkılınç.

The device was recently tested on a dark fibre network installed between Telehouse in East London, UCL, and Powergate in West London, where the researchers were able to send data over 37.6km and 108km. During the tests, eight users were able to download and upload data at speeds of at least 10 gigabits per second.