Using Visible Light for Data Transfer

James Evans writes "Wired has an article about a New Zealand company which has developed a technology to transmit data at speeds up to 400Mbps up to 4km. They are working to have it more resistant to changes in weather, as well as increasing the distance. It has a number of advantages, including lack of federal regulation of the spectrum, as it is of course, visible light." In related terrestrial networking news, waytoomuchcoffee writes "Science Blog reports that the backbone for the World's Fastest Network is up and running. It's a fiber optic 40 gigabit per second connection between Chicago and LA. Teragrid is a project by the National Science Foundation designed to link up supercomputer centers."

Comments

Similar stuff...

[Zapper]

also check out Ronja.

Ronja (Reasonable Optical Near Joint Access) is an Open-Source project of optical point-to-point data link. The design is released under the GNU Public License: you get all the necessary documentation and construction guides free.

It works at 10Mb at up to 1Km.

(here here)...Re:already available and widely used

[the_pooh_experience]

It I am not sure how this is article bestows very interesting or novel information. Granted, the article mentions the wavelengths used are "visible", and "red". My guess is that they are emitting somewhere between 600 and 800 nm (typical visibly range is from 400 nm (purpleish) to 700 nm (red) however this is not a strict cut off, and if bright enough, even above 830 nm is visiblish).

Most telecom takes place at about 1550 nm, well into the infrared, but this is primarily because the typical fiber has nice properties in this range (absorption and dispersion). Therefore I am not sure there is much fundamental difference between infrared light telecom and visible telecom. Indeed they use very similar laser material (GaAs-based or InP-based diodes), are modulated the same way, etc.

Possibly this is neat because it is free-space optical stuff. However this (as pointed out previously) is not new. There are companies that are in place as we speek. Maybe deregulation may be of interest, but if the light it kept at the same wavelength as in fiber, then there is no need for an electronic klugey transceiver (detect the light in the fiber at 1550nm and drive a laser to re-emit the same signal at 6xx nm). Instead, an add-drop filter could be slapped on to the end, pick off the right wavelength, and feed that to a fiber which could be collimated as the source. This collimated beam then could travel over kilometers with no trouble. An all optical solution has a much

just a thought

400Mb? 1 Gb is old news.

[subreality]

Free air optical networking isn't really a new idea. Infrared units are pretty common. I'm not sure what supposed advantage using visible light has over infrared... IR isn't regulated (at least in the US, I can't imagine that it would be anywhere).

I investigated this for networking a couple of buildings my company had near together. Pretty cool stuff. You could get a gigabit connection over a few km of thin air. Cheaper units did 155Mb and for dirt cheap you could get 10Mb. Short range units used LEDs. Longer range ones used lasers.

I've been wondering why consumer ISP's haven't taken to this yet. It's a great last mile solution.

--Keepiru
--slashsuckATvegaDOTfurDOTcom

Re:Federal Regulation

[cyb97]

Not only illegal, but pretty dumb as the houses would have a different grounding and therefore the ethernet cable you've dropped between the houses could end up as the grounding for one of the houses (remember that part about current always taking the easiest route from HS?).
If you want to have your computer/network equipment fried, go ahead and drop what ever you like out the window.
To be on the safe side, drop wireless or optical out the window as optical cables doesn't transmit electricity...