The cost of deploying fiber-optic connections to homes could be dramatically reduced by new hardware designed and tested by University College London (UCL) researchers.

While major advances have been made in core fiber-optic networks, they often terminate in cabinets far from residential users. The so called "last mile" that connects households to the global Internet via the cabinet is still largely built with copper cables, as the optical receiver needed to read fiber-optic signals is too expensive to have in every home.

The "last mile" that connects households to the Internet is still built largely with copper cables. Image credit: Pixabay.Researchers led by Dr. Sezer Erkilinc, of UCL's Electronic and Electrical Engineering Department, believe they have solved the "last mile" challenge by designing a simplified optical receiver that improves sensitivity and network reach compared to existing technologies. The receiver, which contains just a quarter of the detectors used in a conventional coherent optical receiver, can be mass produced cheaply while maintaining the quality of the optical signal.

"We achieved this by applying a combination of two techniques," says Dr. Seb Savory, previously at UCL and now a lecturer at the University of Cambridge. "First, a coding technique often used in wireless communications was used to enable the receiver to be insensitive to the polarization of the incoming signals. Second, we deliberately offset the receiver laser from the transmitter laser, with the additional benefit that this allows the same single optical fiber to be used for both upstream and downstream data.”

The unit retains many of the advantages of the conventional optical receivers typically used in core networks but is smaller and contains 75-80% fewer components, lowering the cost of manufacture and maintenance. Once commercialized, the researchers say, it will lower the cost of installing and maintaining active components between the central cabinet and homes.

"The average data transmission rates of copper cables connecting homes today are about 300 Mb/s and will soon become a major bottleneck in keeping up with data demands, which will likely reach about 5-10 Gb/s by 2025," says Erkilinc. "Our technology can support speeds up to 10 Gb/s, making it truly future-proof.”

The researchers are now investigating the laser stability of the receiver, which is an important step to building a commercial prototype of the system. Once the laser stability has been quantified, they expect to take the receiver design through field trials and into commercialization.