...be three metres long compared to five metres for USB 2. But technology for transferring data over copper wires, like technology for shrinking computer chips, has defied predictions that it will run out of gas.
The short answer is there is a need. Video screens are getting larger, expanding beyond HD TV's 1,920 x 1,080 pixels, and 3D video requires a doubled data-transfer rate. Richard Doherty of the Envisioneering Group expects even the newer DisplayPort video standard has only about 24 to 30 months before new technology needs more capacity than it can supply.
"Optical may be the only way to do it," he said, saying the need for 60Gbps transfer rates is on the horizon.
USB group to standardise Light Peak?
Ravencraft would not comment on whether the USB group is working with Intel on adopting Light Peak for the coming transition to optical communications, but there are indications that could happen.
For one thing, the USB 3.0 specification explicitly accommodates optical lines in the cable's connector, a move to try to 'future-proof' the standard. For another, when Intel demonstrated Light Peak, it used USB connectors on its prototypes. Ziller said in an interview that nothing should be read into that choice, but it was conspicuous nonetheless.
Light Peak discussions are underway at the USB group, said Steve Roux, senior director of business development at NEC and a member of the USB Implementers Forum board.
"Through the USB-IF we're looking at it. It's clearly something we'll have to pay attention to," Roux said. "We don't see it as a USB 3.0 killer."
The politics of standardisation are another reason the USB-IF makes sense for Light Peak. Along with leading developers such as Intel, HP, NEC, Texas Instruments, ST-Ericsson and Microsoft, there are more than 200 companies involved in USB development.
The USB-IF devotes two whole pages crammed with corporate logos in its presentation to illustrate how widespread USB buy-in is. And to meet Intel's ambition, Light Peak will need to win over the video community as well as those who presently use USB.
There are other groups where standards are set — the Institute of Electrical and Electronics Engineers, or IEEE, for example, which oversees the USB competitor FireWire as well as 802.11 for wireless networks and 802.16 for Ethernet networks.
Doherty believes both are possible. The USB group could get a connector defined rapidly for consumer use, and the IEEE could work on a variation for higher-end systems such as servers, with optical lines linking processors together and linking computers to storage systems.
"If this starts out as a 100Gb USB 3F [F for fibre] connector, there's nothing precluding it from going to IEEE and becoming a 10-terabit link with the same connector," Doherty said.
The money question
There is another obstacle, besides politics, that Intel and any allies must reckon with: cost.
Optical networking, in which lasers send information as photons down transparent fibres, does not come cheap.
Doherty believes high-volume production could lower its costs, though. And USB is nothing if not high-volume: about three billion USB devices ship a year right now, according to In-Stat.
"There's every indication that if they get down to USB economics, they can get the cost of the connector down to tens of cents instead of the tens of dollars of most high-performance fibre-optic connectors now," Doherty said.
One way to cut costs would be to use plastic fibres rather than higher-quality glass, Doherty said. That limits data-transfer capacity compared to glass, but plastic is cheaper and also is more flexible, Doherty said. There are signs Intel agrees: Ziller said of Light Peak, "You can tie a knot in it and it'll still work."
Intel has conducted plenty of research into silicon photonics, in which lasers are built into processors themselves, but Light Peak uses more conventional technology for the optical modules that convert ones and zeros into light and vice versa. Ziller said Intel is using optical modules from mainstream manufacturers such as Avago Technologies, SAE Magnetics and Foxconn.
Linking two wires is well understood, but how exactly does that work with two fibre optic lines? Rattner's demonstration featured a hot-plugged Light Peak cable, so evidently Intel has an idea how to make it work economically.
High-end fibre connections are made by fusing the optical lines, but Doherty believes a gel-like adhesive, perhaps protected by a sheath that snaps back when the connector is plugged in, could be used. "It may not be for things you take on and off a hundred times a day," he said, but such a connector could be used dozens or hundreds of times.
Plenty of Intel ideas have flopped, but the company does have more experience than most introducing complicated technology. And it is not putting on the hard sell for Light Peak.
"We're talking hundreds of millions of ports over next the few years, which really will help drive the costs down and make it an attractive technology," Rattner said. "Fundamentally, we believe the time has come for the optical technologies to go high volume."
