A wavelength-division-multiplexing (WDM) visible light communiction (VLC) system employing red and green laser pointer lasers (LPLs) with directly modulating data signals is proposed and experimentally demonstrated. With the assistance of preamplifier and adaptive filter at the receiving sites, low bit error rate (BER) at 10meters and 500Mbps operation is obtained for each wavelength. The use of preamplifier and adaptive filter offer significant improvements for free-space transmission performance. Improved performance of BER of less than 10^−9, as well as better and clear eye diagram were achieved in our proposed WDM VLC systems. LPL features create a new category of good performance with high-speed data rate, long transmission length (over 5 meters), as well as easy handling and installation. This proposed WDM VLC system reveals a prominent one to present its advancement in simplicity and convenience to be installed.
New Scientist – Commonly available laser pointers can zing data through the air across a room twice as fast as most USB cables or Wi-Fi routers. The new optical wireless promises to be cheap and easy to roll out in hospitals and other places where radio transmitters cannot be used.
Engineers at the National Taipei University of Technology in Taiwan picked red and green laser pointers because they are cheap and easy to get hold of. The hardware used in a demonstration cost only about $600, says Hai-Han Lu, who led the work. Combining the two signals yielded a billion bits per second, double the data rates of USB 2.0 or high-speed radio-based Wi-Fi.
Fog, rain and snow make long-distance laser links through air impractical, but they could work for indoor use. A system along these lines could one day be useful for high-speed connections between smartphones.