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'Slow' Light To Speed Up the Net
JPawlak writes "Researchers believe that it may be possible to increase the speed of the Internet by slowing down certain parts of it by using metamaterials. Metamaterials could be used to replace the bulky and slow electronics that route Internet information, allowing for faster Internet speeds. As data nears its destination, the frequencies must be separated. The light must then be converted into electrical signals, which are stored, routed, and converted back into optical signals. The conversion not only adds significant cost and complexity to the process, but slows down the transmission as well. However, if the light signals could be slowed during the switching process, they would not need to be converted into an electrical signal. 'The ability to slow the light could be a tremendous force for telecoms that is sure to enhance speed and efficiency,' says University of California professor Xiang Zhang."
"The metamaterials work of Professor Xiang Zhang and his team at the University of California at Berkeley is being highlighted in a paper Wednesday in the online version of the journal Nature and in another appearing Friday in the journal Science."
http://www.newsfactor.com/story.xhtml?story_id=61321
Yup! It's similar to traffic congestion problem that someone figures out how to solve every couple months. If everyone's driving fast and there's a slow point, all the cars back up. If everyone, hell - if one person, slows down and leaves room inbetween their cars, that gives the tight spot enough room to accommodate the traffic and the congestion dies.
It's a rather simplistic model compared to internet switches, but it sort of works. If you don't overload the switches, you'll have less network congestion. Less Network Congestion=Faster Communication
Give a man a fire and he'll be warm for a day. But light a man on fire and he'll be warm for the rest of his life.
I thought one had to use repeaters every once and a while (every few km?) anyway in fiber optics, which AFIAK work by doing just what this is talking about avoiding, translate light into electrical signals back into light. Why is it so bad to have this conversion happen at the switch if it's already having to happen periodically anyway, and won't using this technique probably just result in more repeaters in the network? Or is it just that the process of multiplexing and de-multiplexing (if I have the term correct) is particularly slow? Can anyone with more detailed knowledge of these systems comment?
"You call it a new way of thinking; I call it regression to ignorance!" -- Operation Ivy
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature07247.html
C'mon, if we ever want to overcome the limits of general relativity and make interstellar travel commonplace, we should be trying to invent ways to make light go faster, not slower!
You know, like on Futurama... right?
I know that person that slows down to give place in heavy 3-lanes traffic at rush hour ... he's an asshole!
Sort of. At the moment, all routing is done electronically. The electronics doesn't have as much bandwidth as the fibres feeding it due to slow response times of electronics. So whenever three or more fibres join, you have an information bottleneck. It would be wonderful if this routing could be done optically, allowing much higher bandwidth routers, removing the bottleneck.
But a router is a bit like a set of traffic lights - if two packets of information travelling to the same destination arrive the router at the same time, then one of them needs to be delayed while the other one is sent through. This requires some way of slowing pulses of light.
Today, these people are claiming that metamaterials will be useful for slowing light, and would thus be useful in such an optical router. I'm a tad skeptical about this at the moment (not sure what the losses would be), and there are several other challenges that need to be met in order to create an optical router.
I think the point is that the light pulses are slowed down enough that they can be manipulated by optical switches. By eliminating two conversion processes, the time between when the pulse arrives at the switch/router/booster and when it leaves is still shorter than with the electronic system. As far as I understand, it isn't related to reducing congestion by "slowing down" packets.
It should be referred to as velocity challenged.
Browsing at +1 - no ACs, I ignore their posts. So refreshing!
Latency vs. bandwidth: ping times vs. download speeds.
The big advantage of an optical switch would not be a decrease in ping times, the advantage is that the switch has far higher bandwidth. Optical components have much faster response times than electronics, so in theory can support many more bits/sec.
Or we could remove the unconstitutional packet sniffing equipment on the backbone.
Modding me -1 troll doesn't make me wrong.
And I should point out that the pulses need to be delayed/buffered as part of the switching process (to avoid packet collisions) - an optical buffer using slow light will be one component in an optical switch.
Demultiplexing multiple channels from an optical fibre isn't routing. This technology could speed the mux/demux stuff up tremendously (saving a lot of cable) but you'll still have a bottleneck at the actual routers that need to read and direct individual packets.
One of these days I'm moving to Theory - everything works there
Yeah, and I know who you are...you're the nut who drives so close behind me that you might as well be in my back seat.
What this is all about is finding some way to do short-term optical packet storage in switches. As yet, there's no optical equivalent of RAM. All-optical gates can be built, and simple logic is possible, but there are no good storage elements. So at present there are optical switches (no queueing), but not optical routers. In order to combine packets from multiple input paths to a single output path, some of the packets need to be delayed until there's free time on the output path. Routers have output queues in RAM to do this. The idea here is to find some way to do this without RAM.
Optical delay lines are simple enough; they're just sections of fibre optic. There are designs for pure optical routers which have little delay loops to which packets can be diverted while waiting for free time on an outgoing line. The delay is fixed, so this sort of thing tends to work better if all the packets are the same size, as in ATM. This new material, where propagation speed varies with light frequency, might be useful as a variable-delay storage medium. Maybe.
This is an area of much active work. Several clever ways have been developed to work around the no-RAM problem. Sort of. None of them are really satisfactory, in the sense of being able to build an optical router that does what an electronic router does now. The network backbone has to be designed around the limitations of the optical technology.
(Note that some optical switches are referred to by their vendors as "routers". They're not. Some of them, the ones with MEMS mirrors, for example, are circuit switches, like a classical phone switch.)
When a packet gets to a network device the body is stored in attached ram and the header is pushed into the routing engine which determines the egress port and queues the packet for TX. When the packets turn for TX comes up the body is retrieved from the ram and pushed down the line.
That memory interface is one of the biggest pain in the rear parts of building a high capacity router.
Now if instead of storing the body in ram you could spin it out around a fiber loopback that'd be mighty handy. You'd save yourself the time and effort of converting, storing, retrieving and reconverting 90% of the data.
Unfortunately life is not that simple, at 10gigabit you get 33bits per meter. That means that a 1500byte frame occupies about 360m, even if you could knock the speed down 90% you would still need 36m of whatever. And that's just so that you can get it all out before it starts coming back in again.
Unfortunately life is not that simple, at 10gigabit you get 33bits per meter. That means that a 1500byte frame occupies about 360m, even if you could knock the speed down 90% you would still need 36m of whatever. And that's just so that you can get it all out before it starts coming back in again.
Your math is off. If we move a wave from one medium to another, the frequency will be preserved, not the wavelength. The "width" of a singal in a slow medium will be far lower as well.
Good point, so since speed = wavelength x frequency, my example of a 90% speed drop will also produce a 90% drop in wavelength so the 360m packet will now occupy 3.6m.
However my implied point that you are going to need a lot of this stuff in your router still holds.
I had a vision of a Japanese commuter waiting for a Bullet train, but the train destination was written on the front of the train and the train didn't stop. Not much of an analogy, but a funny image nevertheless.
I think it was George Carlin who said
Did you ever notice that everybody who drives slower than you is an idiot. And that everybody who drives faster than you is a maniac?
Anthropic principle: We see the universe the way it is because if it were different we would not be here to see it.
The problem is not the math, but the percentage. According to http://en.wikipedia.org/wiki/Slow_light
the speed of light has been slowed down millionfold, allowing for a greatly increased data-density
What?