Exabit Transmission Speeds May Be Possible

adeelarshad82 writes "Scientists at UC Berkeley were able to shrink a graphene optical modulator down to 25 square microns in size (small enough to include in silicon circuitry) and were able to modulate it at a speed of 1GHz. The researchers say that modulation speeds of up to 500GHz are theoretically possible. According to the research, due to the high modulation speeds, a graphene modulator can transmit a huge amount of data using spectral bandwidth that conventional modulators can only dream of. Professor Xiang Zhang, in an attempt to boil his group's new findings into consumer-speak, puts it this way: 'If graphene modulators can actually operate at 500GHz, we could soon see networks that are capable of petabit or exabit transmission speeds, rather than megabits and gigabits.'"

Not at all levels

[Sycraft-fu]

You have to remember that the more bandwidth you want to deliver to the end user, the more you've got to have in the backhaul. Like if at work you want to deliver true 1 gigabit to 1000 people's desktops, you can't very well then have a 1 gigabit connection out to your data center. They won't get a gigabit of performance.

So while speeds like this wouldn't be needed for servers or such, they could be for big links. You want to link big_router_a with big_router_b which have all sorts of very fast connections to smaller routers then maybe this interests you.

Re:Faster than silicon

[drolli]

1. there is a logic which is nearly fast enough. It's called RSFQ, but interfacing it to graphene may be difficult.

2. with RSFQ ADCs.

If its about analog mixing, you could use bolometer mixers, interfacing to RSFQ circuits.

Re:Faster than silicon

[mpoulton]

The modulation problem can probably be solved with clever use of current technology. Initially at least, the only application for links with this bandwidth would be in aggregated data transmission, accumulating dozens or hundreds of lower bandwidth connections. A clever modulation method would utilize multiple separate electrical modulation signals to control the optical modulation, possibly by using multiple separate modulator elements in the optical path, each operating at a lower modulation rate (but synchronized with the others and phase shifted). In the long run it will be interesting to see how data transmission technology evolves to accommodate high data rates like this. 500GHz is hardly even an electrical signal, it's almost light-like. Wires don't work at those frequencies; it's waveguide-only territory. It can really only be handled easily as a modulated optical signal. If we are to progress to a point where data rates like these are practical for individual computing devices we will have to switch to all-optical protocols for networking, and probably also for internal data transport within computing devices. Demodulation of an optical signal with this much modulation bandwidth is pretty much an unsolved problem for now, AFAIK. As with the modulation process, I'd probably try to split it into multiple channels each covering a narrower bandwidth. Unlike the modulation process, I can't think of an obvious way to do that off the top of my head. It's also worth noting that the professor seems to be contemplating the use of many optical modulators (each at 500GHz), each operating on a different fundamental wavelength to multiply the link bandwidth. Hence the prospect of petabit and exabit data rates from 500GHz modulation.