Data travels via speed of white light

Researchers in Germany have demonstrated an ability to wirelessly transfer data at rates of 500 megabits per second (Mbit/s) using white LED light.

The team from the Siemens corporate technology centre in Munich and the Heinrich Hertz Institute in Berlin beat their old record of 200Mbit/s for wireless data transfer using LEDs.

For their recent demonstration, the researchers used a white light-emitting diode produced by the Siemens subsidiary Osram and transmitted data over a distance of up to 5m of empty space.

Data was directly transferred by modulating, through the power supply, the amount of light emitted by the LED. The researchers used an Ostar LED and modulated it at such a frequency to achieve up to 500Mbit/s transfer rates.

LED stoplights or railroad signals could be used to transmit information to cars or trains

These changes in brightness are reportedly imperceptible to the human eye, yet can still be perceived by a photodetector, which acts as a receiver and converts the light signals into electrical pulses.

It is believed this form of data transfer called VLC (Visible Light Communication) has a variety of potential applications such as WLAN technology. For example, wireless networks are often compromised by the fact that in many buildings the three independent WLAN frequency bands are multiply occupied, which leads to collisions among the data packets. In a situation like this, visible light could be a suitable alternative.

The research team also sees a further application in the field of transportation, where LED stoplights or railroad signals could be used to transmit information to cars or trains.

The IEEE (Institute of Electrical and Electronics Engineers) has been working since 2007 to standardise activities in this field. It is hoped that this work will be completed by the end of 2010.