'Twisted light' could enable 100x faster internet speeds

Friday, 16 November, 2018

'Twisted light' could enable 100x faster internet speeds

Researchers at RMIT University have unlocked a way to carry more data, and process it quicker, than the fibre optics of today — potentially allowing for internet speeds 100 times faster than what we’re used to.

Currently, optical fibres carry information on pulses of light, at the speed of light — but the way the light is encoded at one end and processed at the other affects data speeds. Fibre-optic communications like those used in the national broadband network use only a fraction of light’s actual capacity by carrying data on the colour spectrum, while new broadband technologies seek to use the oscillation, or shape, of light waves to encode data — increasing bandwidth by making use of the light we cannot see.

Now, researchers at RMIT’s Laboratory of Artificial Intelligence Nanophotonics (LAIN) have built a nanophotonic device that encodes more data and processes it much faster than conventional fibre optics. Described in the journal Nature Communications, the technology carries data on light waves that have been twisted into a spiral to increase their capacity — known as light in a state of orbital angular momentum, or OAM.

“Present-day optical communications are heading towards a ‘capacity crunch’ as they fail to keep up with the ever-increasing demands of big data,” said Dr Haoran Ren, co-lead author of the paper.

“What we’ve managed to do is accurately transmit data via light at its highest capacity in a way that will allow us to massively increase our bandwidth.”

In 2016, the LAIN team published a disruptive research paper in the journal Science describing how they’d managed to decode a small range of this twisted light on a nanophotonic chip. But technology to detect a wide range of OAM light for optical communications was still not viable, until now.

“Our miniature OAM nanoelectronic detector is designed to separate different OAM light states in a continuous order and to decode the information carried by twisted light,” Dr Ren said.

“To do this previously would require a machine the size of a table, which is completely impractical for telecommunications. By using ultrathin topological nanosheets measuring a fraction of a millimetre, our invention does this job better and fits on the end of an optical fibre.”

Professor Min Gu, LAIN Director and Associate Deputy Vice-Chancellor for Research Innovation and Entrepreneurship at RMIT, said the materials used in the device are compatible with silicon-based materials use in most technology, making it easy to scale up for industry applications.

“Our OAM nanoelectronic detector is like an eye that can ‘see’ information carried by twisted light and decode it to be understood by electronics,” he said. “This technology’s high performance, low cost and tiny size makes it a viable application for the next generation of broadband optical communications.

“It fits the scale of existing fibre technology and could be applied to increase the bandwidth, or potentially the processing speed, of that fibre by over 100 times within the next couple of years. This easy scalability and the massive impact it will have on telecommunications is what’s so exciting.”

Prof Gu said the detector can also be used to receive quantum information sent via twisting light, meaning it could have applications in a whole range of cutting-edge quantum communications and quantum computing research.

“Our nanoelectronic device will unlock the full potential of twisted light for future optical and quantum communications,” he said.

Image caption: To the left is the schematic of CMOS-integratable OAM nanometrology. An ultrathin OAM-dispersive plasmonic topological insulator film is constituted by spatially shifted semicircular nanogrooves and mode-sorting nanoapertures, through which the OAM-superposed beams are spatially separated and directly measured by a CMOS detector in the far-field region. To the right is the multilayer structure of the topological insulator thin film as well as the cross-section of nanogrooves. Image courtesy of the study authors under CC BY 4.0

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