Apparently LED light bulbs
have more uses than just providing illumination. Researchers at Siemens, in collaboration with the Heinrich Hertz Institute in Berlin, have achieved a data transfer rate of up to 500 megabits per second (Mbit/s) using white LED light. This crushes their previous record of 200 Mbit/s and paves the way for wireless data transport by means of light in new applications in the home as well as in industry and transportation.
Using a white LED from Sylvania, the researchers from Corporate Technology in Munich succeeded in transmitting data over a distance of up to five meters of empty space. The data are directly transferred by modulating, via the power supply, the amount of light emitted by the LED (basically turning it off and on extremely quickly). The researchers used an Ostar LED, one of the brightest LEDs on the market, which can be modulated at such a frequency that data transfer rates of up to 500 Mbit/s are possible. The resulting changes in brightness (flickering on and off) happen so fast they are imperceptible to the human eye. The receiver is a photodetector which converts the light signals into electrical pulses.
This form of data transfer is called VLC (Visible Light Communication) and has a variety of potential applications. In homes and businesses for example, it could be a valuable addition to established WLAN technology. Wireless networks are increasingly being compromised by the fact that in many buildings the three separate WLAN frequency bands coexist, which leads to collisions among data packets. In a situation like this, visible light offers a perfect alternative.
A network using VLC also prevents wireless "squatting", where a person logs into a secure (if they break the password) or unsecure network and steals bandwidth. In a VLC network, only the photodetectors that are positioned directly within the light cone are able to receive data. Further use of VLC technology would be in factory and medical environments, where in certain areas radio transmissions are impossible or very limited. This is fascinating stuff, and the opportunities are nearly endless.