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Fiber Optic World Records Broken
Thousands of miles of existing fiber still lie dark, but as
schnucki writes, "Bell Laboratories believe they have broken two world records in the use of optical fibres to transmit information." They sent 160 gigabits/sec on one wavelength, and then in a separate experiment sent 1,022 separate wavelengths down one fiber. You do the math.
Check it out.
I'm just curious what the error rate is. Can you send that much data without loosing a few bits. I'm impressed with the numbers regardless, but if you have a 50% error rate is that good? Also if you loose one bit per byte, can you clam anything? Did they only count the good bits sent?
;). If you send 160 Gb/s (20 GB/s), can you convert that to electrical data without making a bottleneck. I'm not an expert in this area, but I'm curious to know.
Also, what is the speed to transfer the light signals to electrical. I don't have (or have I ever heard of) an optical computer, would be nice though
Steven Rostedt
Steven Rostedt
-- Nevermind
I think the most impacting news is that optic "router". That is going to have the biggest effect. We dont' need 160gb/s if it has to be converted into an electronic signal everytime it switches fiber lines.
This isn't really revolutionary new technology.. we've known about stuff like this for awhile. There's a nearly infinite number of ways to encode frequencies, and stack things onto each other.
I find myself wanting of the ability to insert IMG tags here. :( In short, picture a sine wave. Now along the slope of one, picture another sine wave attached to it. And so on. I suspect they're doing something like that. Actually, TVs do something like this - it's how the sync pulses and whatnot work. Very facinating technology. Also very old by today's standard, but still very useful.
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If you have a really short pulse length of e.g.
10 fs (= 10^-14 s!) the spectral range of this
puls covers the whole visual spectrum. If you
pick out a small range of this spectrum using
a grating you will enlarge the length of the
pulse (if you have a pulse with a length of one
ns you can't determine the frequency of this
pulse with a higher precision than one GHz and
vice versa).
With fibre gratings you might be able to pick
out a large number of different spectral ranges
which can then be modulated individually before
they are once again combined and put into the
fibre. With 1550 nm wavelength the required spectral range should be at least about +- 100 nm!
for a data bandwidth of 20 TBits/s
Nevertheless it is really amasing!
Varying the intensity of a light source creates "sidebands", the same as it does for RF. These "sidebands" are wavelengths slightly longer and shorter than the "carrier". What you see as an amplitude variation is really the interference of the carrier and the sidebands, as they slip in (high amplitude) and out (low amplitude) of phase over time. If you have a carrier frequency of F and a modulation frequency of M, you'll create sidebands at F+M and F-M. If you have really good filters you can suppress one of the sidebands and still carry all the information, and if you have really good frequency references as well you can ditch the carrier and only bother sending one sideband (you can use the frequency reference at the receiving end to supply the "carrier" for demodulation); this is how SSB radios work.
What does this mean for optical fiber? It limits how close together your "colors" can be based on how fast each one is modulated. The sidebands get farther and farther from the carrier as the modulation gets faster, and if the sidebands start clashing you get crosstalk and data errors.
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Time is Nature's way of keeping everything from happening at once... the bitch.
The speed of light through any medium is less than the speed of light in a vacuum. Sometimes light can be made to travel through a medium faster than it's natural rate. This results in a nifty "light shockwave" which I believe is called cherenkov radiation.
:-)
Yep. You can see some cool pics of this effect at http://www.nuc.umr.edu/Reactor/Reactor.ht ml, along with a pretty good explanation of how. It's pretty neat the way it actually happens..
Furthermore, the light in a fiber actually zig-zags down the fiber channel and does not travel straight down it. This also reduces the signal's speed from c.
Actually it increases the distance of travel which gives an appearent speed difference from c, which is just as good as slowing it down.
---
- Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
*sigh* People keep getting rate of propogation confused with rate of transfer. This is latency vs. bandwidth folks.
For instance, consider the ancient communication method consisting of two people atop hills signalling with lanterns and shades. The latency is really low because the light propogates at near 3e8 m/s in air. The bandwidth sucks. Now consider a freight-train loaded to the gills with DVD-ROMs. The bandwidth is enormous, but the latency sucks.
The speed of light governs how quickly a packet of data gets from point A to point B. Bandwidth measures the total number of packets of data that you can send from point A to point B at a given time. The two are different, unless you somehow treat each photon as its own packet of data, and we're not there yet.
--Joe--
Program Intellivision!
We'll run fiber to the homes shortly, if something isn't developed soon that's even better. (Take a look at the recent Scientific American articles on the current candidates.)
Individual fibers to the home are a lot of bux. But a multiwavelengh fiber to the neighborhood and a passive wavelength divider (think prisim) and a bunch of short fibers to the house look like a good cost-tradeoff.
But having the government pay for it means you get to pay for whichever solution they chose at least three times - once for the install, twice more for the administrators. And the government will chose the wrong one. And the government won't even chose the best price/performance combo for the data rate they do chose.
Sure the government built the Interstates (kinda). And then they installed a 55 MPH speed limit - city, prarie, or deserted desert. Let them wire your home (or your kid's school) and they'll do it badly, expensively, and use it as a wedge to control the content.
The fact that I can plug in a *crank* telephone (not pushbutton, not rotary,... a crank phone) from 189x and *still* use it to make and receive calls on POTS lines should say something about the state of telephone tech in supposed advanced nations like the US.
Actually, it says more about good standards lasting a long time. Just like the Roman's choice of wheel spacing affecting cars, trains, and spacecraft components (that are shipped on trains) to this day.
The POTS standard is about getting audio from the switch in the city to the houses in the city and to the farms around it. The last mile of the audio part of that job hasn't changed materially since Bell and Strowager. A cheap low-tech solution does it, so why pay a bunch of bux to replace it with something that doesn't interact? Especially when doing so creates an administrative nightmare for no advantage.
Data is now hitting the wall on the capacity of the infrastructure designed for voice, so you need to replace part or all of it to go beyond.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way