1Gbps Wireless Network Made With Red and Green Laser Pointers

MrSeb writes "Back in the olden days, when WiFi and Bluetooth were just a glimmer in the eye of IEEE, another short-range wireless communications technology ruled supreme: Infrared Data Association, or IrDA for short. IrDA was awful; early versions were only capable of kilobit-per-second speeds, and only over a distance of a few feet. Trying to get my laptop and mobile phone to link up via IrDA was, to date, one of the worst tech experiences I've ever had. There's a lot to be said for light-based communications, though. For a start, visible (and invisible) light has a frequency of between 400 and 800THz (800 and 375nm), which is unlicensed spectrum worldwide. Second, in cases where you really don't want radio interference, such as hospitals, airplanes, and other sensitive environments, visible light communication (VLC), or free-space optical communication, is really rather desirable. Now researchers at the National Taipei University of Technology in Taiwan have transmitted data using lasers — not high-powered, laboratory-dwelling lasers; handheld, AAA-battery laser pointers. A red and green laser pointer were used, each transmitting a stream of data at 500Mbps, which is then multiplexed at the receiver for a grand total of 1Gbps."

Wheres the "news" part?

[Anonymous Coward]

Laser based FSO isn't exactly a new field.
1Gbps data rate with a diode laser isn't that hard to achieve even with pretty simple drivers and 1-bit amplitude modulation.
Neither is using wavelength multiplexing some revolutionary new idea.
So... huh?

Re:Wheres the "news" part?

[sveinb]

Well, that's what I thought until I tried. Connected a laser pointer to a signal generator and measured its light output. As the frequency increased above about 1 MHz, the modulation level decreased to a non-usable level.

Re:Not new

[Anonymous Coward]

Radio hams have been experimenting with point to point communication by light. It's been mountain-top to mountain-top so needs quite precise alignment. Also the data rates have been quite low - more voice. But the technique is quite old. We've known about modulating laser diodes for some time.

A quick search reveals this site reporting a 104 mile link using LEDs. http://www.bluehaze.com.au/modlight/