Oct 21, 2013

    Light waves speed up Net access

    SCIENTISTS at Fudan University have come a step closer to using light to connect to the Internet.

    The scientists from the School of Science and Technology at Fudan University recently succeeded in accelerating the speed of Internet access through light waves to speeds exceeding those of current networks in a lab experiment.

    Wi-Fi uses radio waves, while this LED-based alternative, dubbed Li-Fi, or Light Fidelity, uses light to deliver a high-speed communication connection. As with radio waves, light is also a type of electromagnetic wave, but it has about 100,000 times the frequency of a Wi-Fi signal.

    Li-Fi was first demonstrated by University of Edinburgh professor Harald Haas in Britain in 2011.

    The Fudan University researchers said they modulated Internet signals to a 1-watt LED lamp. Under the light, four computers were able to access the Internet.

    The offline maximum speed reached 3.7 Gbps which, scientists said, is the world's fastest Internet access speed via LED light.

    "A video programme was successfully delivered between two computers at this speed in our experiment," said Professor Chi Nan, who led the research.

    Prof Chi said the potential applications of such technology are enormous, but there is still much work to be done.

    One question for the research team is how large an LED light to install on the computer or mobile phone so as to support data retrieval.

    "It's obviously not practical to install a large light bulb on the computer," Prof Chi said.

    Another problem faced with Li-Fi is that the signal is lost when the light is blocked.

    Mr Zhu Jie, an industry insider who works in a telecom company, said: "Li-Fi can work as a supplement to Wi-Fi, and to free the spectrum space. Compared with existing Wi-Fi technology, visible-light communication is safer and causes less radiation."

    Besides supplementing existing networks, Li-Fi can also be used in hospitals where radio signals need to be kept to a minimum, or where they don't work, such as underwater, website Quartz reported.

    "It may need quite a long time to apply to real life. The promotion of such technology may rely on wide application in certain fields," Mr Zhu added.

    Ten computers with Li-Fi technology will be displayed at the 2013 Shanghai International Industry Fair next month.