Intel announced optical cables for Thunderbolt will start shipping later this year. The fiber optic cables will enable faster data transfers over a larger distance than presently available copper Thunderbolt cables, but the downside is that they will be more expensive and that devices that need power will also require their own power supply. Existing Thunderbolt ports are compatible with both kind of cables.
Intel has said copper cables are adequate for data transfers over short distances of up to six meters. Optical cables will be good for data transfers over longer distances of tens of meters.
The upside to optical is that it allows for longer cable runs, and as the technology develops, more bandwidth, Salvator said in email. But when connected via optical cables, devices that need power also require their own power supply. Running power over longer optical cable runs may not be practical due to impedance-induced power drop.
Copper has the advantage of providing up to 10 watts of power, which saves a device from requiring a power outlet, Salvator said.