Laser Li-Fi boasts 100 Gb/s data rate

Researchers at the University of Edinburgh in the UK have put a new twist on Li-Fi technology which could offer 100 gigabits per second wireless data transfer speed. Traditional Li-Fi encodes data on the light coming from LEDs by modulating their output. The Ultra-Parallel Visible Light Communication Project has added a new dimension to this by using laser diodes that can be modulated at 10 times the speed of LEDs, and offer 10 times the data transfer rate.

InAVate reported on the group’s progress last year in developing Li-Fi technology, a two-way communication that uses the rapid flickering of light between a receiver on a computer or mobile device that can read signals and send them back to a transceiver. The potential for LED-based transfer was expected to be around 15 Gb/s at that time, but this was based on the limitation of using LEDs that use a phosphor coating to convert blue light to white, which slows modulation speed and data rates.

The research group have now boosted modulation rate with off-the-shelf laser diodes that can work at 10 times the rate of LEDs. The Edinburgh group used nine laser diodes in an experiment that saw white light created by mixing the output of several lasers operating at different wavelengths. Each wavelength is used as a separate data channel in a similar way that wavelength division multiplexing allows optical telecommunications to carry vast amounts of data.

Such a setup would be prohibitively expensive at the moment but the researchers believe that mass production will bring down the cost of the lasers and move them into lighting applications.
The Ultra-Parallel Visible Light Communications project is a collaborative effort between researchers at the Universities of Edinburgh, Oxford, Strathclyde, St Andrews, and Cambridge.