Oxford researchers use Li-Fi-like system to deliver 100 Gbps

Researchers at Oxford University are using light to deliver data to a computer at more than 100 gigabits per second, with the potential for data rates of 3 terabits per second and up.

The indoor optical wireless technology probably would not replace Wi-Fi, but it may wind up being part of how people link devices to the Internet, according to IEEE Spectrum. The research is described in IEEE Photonics Technology Letters.

It's all related to efforts to develop light fidelity, or LiFi, which uses light running at a much higher frequency than radio waves to transmit data. LiFi uses the light that's illuminating a room as a way to send data signals and usually refers to schemes based on visible wavelengths of light, whereas the Oxford system relies on infrared light at 1550 nanometers that's familiar to the telecommunications industry.

The research team installed a base station on the ceiling of a room, which projected the light toward the computer and also received data from the computer going out to the Internet. In this set-up, the light beam has to be exactly where it needs to go, so the team used so-called holographic beam steering at both the transmitter and receiver ends. It also used an array of liquid crystals similar to that used in projectors.

The device relies on wavelength division multiplexing, which splits the signal into slightly different colors of light. With a 60-degree field of view, the team was able to transmit six different wavelengths, each at 37.4 Gb/s, for an aggregate bandwidth of 224 Gb/s. With a 36-degree field of view, they managed only three channels, for 112 Gb/s, according to IEEE Spectrum.

The system requires a direct line of sight, and for now the receiver must be in a fixed position. Dominic O'Brien, a photonics engineer who directed the work, told IEEE Spectrum that the next step is to develop a tracking and location system so that a user could place a laptop at a random spot on a table and have the system find it and create a link.

Researchers from University College in London also participated in the project.

Various universities around the world are studying Li-Fi as a complement to capacity-challenged Wi-Fi and cellular networks. Li-Fi supporters contend that using the vast amounts of readily available free and unlicensed visible light could solve issues of limited and congested RF spectrum and deliver much faster wireless speeds.

For more:
- see this IEEE Spectrum article
- see The Telegraph article
- The Register has this article

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