Didn't know about the relative time frames of pulse and survival of the light guide
But this has been talked about for decades.
The big one is making the "pipe" conductive.
So a laser lightening rod you can shine at the sky.
You may think that a waveguide is something issued to junior members of the royal family ahead of their first pomp parade through London. But it's actually a new communications technique that makes the air behave like a fibre-optic cable. Howard Milchberg, professor of physics and electrical and computer engineering at the …
Im sure i read once about trying to make a plasma channel using incredibly short pulses from a UV laser that became self focusing due to the physics.
However if it was achieved it wouldnt be used for anything as humanitarian as dissipating lightening (preventing a fair few wildfires) it would herald the era of Tom Swift's electric rifle and even more efficient warfare.
That Destroy the emitter... Done n Dead.... The Military / Darpa gave up on this years ago n went to Chiped Pulse Compression that multiplies the power to Peta-Watt levels and avoids non - linear standing waves...note: the optical amplifiers are EDFA / Erbium Doped Fiber Amps using Quantum pump / freq power injection...
Ref= Wiki - Chirped Pulse Amplification...
IMHO= it would take several thousand of these things to equal todays communication density in just about any area...RS.
"The American military has previously shown interest in sending messages over the air, using "mobile optical links" which are "imperative for secure quantum communications capabilities"."
Maybe I've not quite got the hang of this, but I'd have thought that putting enough laser power into the atmosphere to ionize it and create a plasma channel would in itself cause a fairly bright flash of light. Presumably that would be fairly easily seen or detected from a long way away.
I don't suppose that would be entirely popular with soldiers, sailors or airmen; secure communications that cannot be intercepted that none the less gives your position away with a big bright flash to everyone within your field of view...
If you have a laser that is powerful enough to ionise air, why not just dial the power down a bit and send your signal using it? A laser beam visible at 1km is going to use vastly less power than a laser than can ionise a channel of air 1km long.
Sounds a bit like using a nuclear bomb to send smoke signals with the mushroom cloud...
AC makes a good point.
If they use this technique in practice, then some technician will eventually discover that if he switches some wires around he can use the high power, air-heating laser to send the data even further.
At least this report is better than CBC which stated that this technique would allow data transmission "anywhere in the world", neglecting the curvature of the Earth, and "into space", neglecting that it would be difficult to heat air in a hard vacuum.
I have recorded that documentary, but have yet to watch it. I shall do so very soon, because I am sure there is much to learn from it.
And I'm sure I've seen another in recent years that involved flying sharks. There may or may not have been time travel, as well - but I can't remember.
...at least not in anything "communications grade". Of course it will for cheap SPDIF-like systems, but if you want to reach high speeds you encounter a rather simple problem: The parts that bounce around will take considerably longer to arrive than the parts which go through straight through the middle. This may not sound like a lot, but it adds up. If you have a 100km cable a percent longer or shorter ways can really spoil your bandwidth.
Instead fibre optic cables actually work more like microwave waveguides by providing an environment where, ideally, only the wave you are interested in can exist. This involves lots of math.
Multi-mode fibre does "bounce" the light around whereas single mode fibre acts as you had described. MMF is still widely used in data centres (with SR optics) though many people has realized that for green-field it makes sense to go all-SMF (LR equivalent optics on-premises and shorter distances outside; ER, ZR etc. for long-haul).
"You may think that a waveguide is something issued to junior members of the royal family ahead of their first pomp parade through London. But it's actually a new communications technique that makes the air behave like a fibre-optic cable."
As any fule kno, waveguides has been around since microwave transmission was invented and fiber optic cables keep light in the core due to total internal reflection, making the cable a waveguide. And fiber optics has been around a while too, so waveguides is old stuff.
"As most Reg readers will know, fibre-optic cables work by bouncing a light beam along a wire..."
As any fule also kno, you can't shine a light beam through copper!
This sounds very interesting for things like remote sensing (I'm sure the Curiosity would love to have such a device on it) but for comms?
Isn't it much easier to just modulate 1 weak laser with your signal and use it for any length of time you want than to fire a Gatlingful of high-power beams just so that your blinking flashlight could be seen from a distance for a millisecond or so?
So strong, but imprecise laser for creating the 'tunnel' and weak, but precise and fast laser for sending the data?
It does make sense. I would believe that it is hard to modulate a laser that is powerful enough to have an 'impact' at distances of over a km, to precisely transmit high-bandwidth data, while it would be also difficult to make a high-precision laser strong enough to have a signal that doesn't degrade before 1km of air-way. So basically pairing up two different lasers to compensate for each others weaknesses?
As most Reg readers will know, fibre-optic cables work by bouncing a light beam along a wire without losing focus or intensity, allowing information to be transmitted along huge distances at massive speeds.
So, roughly the speed of light in that medium? Fast enough for the data to acquire mass? Sorry, I am caffeine deficient this morning.
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