Even though Intel Corp. and its partners decided to omit optical cables for Thunderbolt interconnection technology this year, next year the world's largest maker of chips hopes that active optic-fiber cables will emerge. While those cable will not improve performance, they will extend the length and introduce new usage models.

At the Intel Developer Forum the backers of Thunderbolt interconnection technologies - lead by Intel itself - revealed that the next-generation active optical cables coming out next year will support length of up to tens of meters (or even up to 100 meters as defined by the initial spec), a major improvement over current three meters that are supported by active electrical cables. Performance of Thunderbolt interconnection will remain on the level of 10Gb/s since the speed is limited by existing controllers.

Currently available devices with the new interconnection - notebooks, desktops, external hard drives and other - are projected to be compatible with the next-generation active optical Thunderbolt cables.

The cost of active optical cables will likely be very high, hence, they will barely be bundled with actual devices. As a result, actual adoption rate of active optical-fiber Thunderbolt cables will be very slow despite of their compatibility with existing and future devices. It also remains to be seen whether the new cables will also support higher bitrates that are likely to be a feature of next-gen Thunderbolt controllers.

Previously known as Light Peak, Thunderbolt technology supports two low-latency communications protocols - PCI Express for data transfer and DisplayPort for displays. Thunderbolt technology works on data streams in both directions, at the same time, so users get the benefit of full bandwidth in both directions, over a single cable. With the two independent channels, a full 10Gb/s of bandwidth can be provided for the first device in the chain of the devices. All Thunderbolt technology devices share a common Mini DisplayPort connector. Intel's Thunderbolt controllers interconnect a PC and other devices, transmitting and receiving packetized traffic for both PCIe and DisplayPort protocols and thus makers need to develop or use additional controllers to make their products compatible with the TB I/O interface.

Not a lot of devices these days can take advantage of Thunderbolt. Only external graphics cards, external solid-state drives as well as RAID-based storage solutions, professional equipment and some other applications need 10Gb/s demand. As a result, USB 3.0, which can theoretically provide up to 5Gb/s bandwidth, will continue to serve the majority of devices that exist today.

Tags: Thunderbolt, Intel, Apple, WD, Seagate