28 May Researchers develop 100Gbps light-based wireless network – Telegraph
Researchers develop 100Gbps light-based wireless network
Oxford researchers are working on a wireless communications system that uses light rather than radio waves to send data
By Sophie Curtis1:22PM GMT 16 Feb 2015 2 Comments
Researchers at Oxford University are developing a wireless networking technology that uses light to beam information through the air at more than 100 gigabits per second (Gbps).
The technology could eventually provide a much faster alternative to WiFi, which currently tops out at about 7 Gbps.
Light is already used to transmit data across fibre optic networks at high speed. These work by guiding the light along optical fibres using total internal reflection, so that no information is lost along the way.
However, transmitting information by beaming light through the air is more difficult, because there is no ‘light tunnel’ to guide the signal to where it needs to go.
The researchers, led by photonics engineer Dominic O’Brien, have developed a system that uses a base station installed on the ceiling of a room to send and receive light signals from a computer.
The transmitter and receiver are both fitted with holographic beam steering technology, which uses an array of liquid crystals to create a “programmable diffraction grating” that reflects the light in the desired direction.
The technology works at distances of up to three metres, but the system requires a direct line of sight, and for now the computer must be in a fixed position, according to IEEE Spectrum.
The speed of the system also depends on the field of view of the receiver; if the base station has a 60-degree field it can use six wavelengths, while a 36-degree field only supports three wavelengths.
The next step, according to O’Brien, will be to develop a tracking system so that a user can place a laptop at a random spot on a table and have the system find it and create a link.
O’Brien’s work is part of a larger effort to develop light-based wireless communications (known as LiFi), which uses the light that is already illuminating a room to send data signals.
Last year, for example, British hi-tech start-up PureLiFi (spun out of the University of Edinburgh) announced a light bulb fitting capable of acting as the equivalent of a wireless network in the home. PureLiFi has also demonstrated light-based communications at 100 Gbps.
LiFi usually refers to schemes based on visible wavelengths of light, according to O’Brien, whereas this system relies on infrared light at 1550nm, which is used in telecommunications.