Thunderbolt ports on the latest Macs already support optical cabling, according to Intel. New fiber optic cables, which will allow connections as long as "tens of meters" instead of the current three meter limit for copper cable, should be available in 2012.
Thunderbolt started life as an optical interconnect codenamed LightPeak. Developed by Intel with input from Apple, it was designed to ramp from 10Gbps to as high as 100Gbps using silicon photonics. Several factors—in particular, costs associated with fiber optic cabling—resulted in the initial version using electrical-only copper cabling.
When Intel introduced Thunderbolt as part of the launch of Thunderbolt-equipped MacBook Pros from Apple, the company indicated that the standard could use either electrical or optical cabling. Intel spokesperson Dave Salvatore confirmed to IDG News this week the compatibility between existing Thunderbolt ports and the upcoming optical cabling.
What makes it possible to use the same connector for both electrical and optical versions of Thunderbolt is a design that puts the controller in Thunderbolt devices and the transceiver in the cables. Current Thunderbolt cables use a Gennum transceiver at each end and copper cable in between. Replace the Gennum transceiver with an electrical-to-optical transceiver, copper wires with fiber, and bam!—optical Thunderbolt.
When the new optical cables will be available, and for what price, has yet to be determined. However, potential buyers should be prepared to spend more than the $50 it costs for a 3 meter copper cable from Apple. Dadi Perlmutter, Executive Vice President and General Manager of the Intel Architecture Group, told IDG News that adoption of optical cables will largely depend on "how much [users] would be willing to pay." In other words, if you don't need long cable runs, you could just stick with electrical cables.
Still, optical cabling is necessary to move Thunderbolt beyond its current 10Gbps bandwidth. Intel is currently targeting 2015 for a 50Gbps version, for instance, and believes it can reach 100Gbps within a decade. Faster versions of Thunderbolt will presumably retain the Mini DisplayPort-style connector. Controllers will then be able to negotiate connection speeds by communicating with the transceiver in the cable. If the cable is optical, transmission could operate as high as 50Gbps in each direction. If the cable is electrical, data will be limited to 10Gbps in each direction. According to Perlmutter, that will allow users to pay more for faster throughput only when it's needed.
Device makers are slowly but surely getting Thunderbolt-compatible products to market—including drives, RAIDs, hubs, video editing boxes, at least one Thunderbolt display—and a variety of storage makers have told Ars that more products are in the works. Sony and HP have backtracked on their initial support for the standard, but both Acer and ASUS have committed to building Windows machines with standard Thunderbolt ports using updated controllers that should be available in the second quarter of next year.
