Corning Thunderbolt Optical Cable 3.5m (12ft) for Self-Powered Peripherals AOC-MMS4CVP3-5M20

This is hands down the best cable available. I can't believe we lived with a computer for so long without demanding optical cables. Finally, Corning makes it affordable to have optical cables in everyday use.

These aren't cheap but work flawlessly. The only option when you need more than 2M to do thunderbolt 2 connections properly. Using this between a sonnet zmax server and a Thunderbolt Raid. End connectors are built well too.