Last night I met an interesting inventor. He’s been involved in the invention of WiMAX, among many other things and is the founder and chief technical officer of CeLight.
But last night he showed me a laser system that could provide a community with much more bandwidth than even a fibre optic line (he claims his system will bring four to five times more bandwidth).
It’s not a point-to-point laser, either. Instead of aiming the laser at a sensor across the land, he saw the light at the top of the Luxor hotel and thought that is actually an interesting way to bring bandwidth to a community.
Last night he showed me how it works. A purple laser which is almost invisible to the human eye and which is inexpensive to buy (they are the lasers inside every Blu-Ray disk player — the lasers are actually purple light, the “blu” in the name is marketing) is aimed at the sky and an array of sensors reads data from the beam of light. Readable due to scattering of light due to the atmosphere. He showed me how this works: you aim a laser at the sky and everyone can see the beam. If your human eye can see it, sensors can see it too and due to some tricks can get massive amounts of bandwidth out of the laser.
I was fortunate enough to meet Isaac and here he explains how it works.
Why is this important? Because aiming a laser at the sky is a LOT cheaper than digging and laying down fiber. So, this might be how lots of areas get high-capacity backhaul capabilities. Translation: we’ll all get cheaper broadband that we’ll need to keep up with future HDTV and 3DTV.
Scobleizer 
That’s about tranmission and multiplexing in a point to multipoint scenario. But what about multiple access? How does the user talk back to the source?
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FAA won't come down on that?
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Being visible light, pointed straight upwards and deliberately scattering widely, this should be fine: the FAA's objection would be to any tightly-focussed directional beam which might shine into cockpits. After all, much bigger and brighter lights shine like this already – and if this data-laser did have the potential to impair vision, it wouldn't just be the FAA who would object.
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We did a demonstration. Purple lasers are VERY HARD for humans to see, which is one of the reasons he picked purple. But there is another reason: the sun doesn't kick out any photons in that spectrum, which is probably why it is hard for humans to see that light, but it makes it very easy for sensors to see that light.
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Have a laser of your own on your roof.
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But this is why it probably would only be for backhaul (major points for major bandwidth, not delivery to the home).
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It sounds like an interesting demonstration, but I’d challenge the inventor to show that it could ever be anything more than that. The comment about return path is an obvious one (I don’t think anybody would claim that thousands of these lasers could exist concurrently), but key when you look at the complications of broadband delivered over satellite as a downpath and the return over DSL. The 100-year old copper access networks originally installed for telephony are aging and need replacement in any case. It would be ridiculous to put more copper in, so if one agrees with the concept of fixed lines, homes will be fibered-up in any case.
As far as backhaul is concerned, that is a smaller investment than mass distribution, slightly implying that this is a solution looking for a problem. What would be the maximum range that a link could operate over? Would it be secure against eavesdropping (presumably encryption would be overlaid)? Could a malicious force take out the whole signal simply by broadcasting at the same frequency? What would be the effect of atmospheric variations? Would it work in rain, snow, etc?
Until all these issues are clear, I’d suggest using visible wavelengths and sticking to lighting up the clouds for fun!
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Weather variability is another issue. A good fog, or rain would be an issue. Making sure a bird doesn't crap over the output end, or a lucky hit from a hail stone. It's intriguing, even if it's just for backhaul. But you're still going to need some kind of backup. And then there is the power that comes with that type of laser. It seems to me that somebody ripped the diode out of a blu-ray player and was using it to pop balloons. Now maybe it was cranked up, so that really isn't an issue.
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There are so many interesting broadband signal technologies that have been born over the years. I was fortunate enough to consult with a group years ago who had what's commonly referred to as a 'spare pair' technology; one of the many – like DSL – that used the other pair of copper wires already in standard residential phone lines all over the planet. This thing achieved Full-motion 30fps video and full-duplex stereo audio over single copper and dual strand (aka the spare pair). It was amazing to see what was at the time an average desktop PC handle 4 completely different video feeds from a locally connected video cam to outside surveillance cams to two video conference calls from two different places in the country. There was a military application where advanced interactive comms were run between a rear command post to a forward position across a single copper strand hastily strung through the dust. A really long, thin nearly impossible top spot wire carrying mission-critical signal an incredible distance.Unfortunately, the propellerheads behind the technologies achieving fiber optic quantities and qualities of bandwidth couldn't run their company very well. The familiar refrains that so often plague innovative tech companies sunk this one: 'more brains than money', and it's not who you know, it's who knows you.Hopefully, if the laser tech these folks have developed is sound and can live in real-world conditions outside of the lab, then we'll see it emerge. The only thing that could kill it then would be the telcos and cable companies who're dead set against these technologies because of the sizeable bite they take out of profits.
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