How Does a Digital Optical Audio Cable Work?

A digital optical cable, also called a TOSLINK (Toshiba Link) cable, is a fiber optic cable that can be used to connect digital components, such as DVD and CD players, to receivers in a home theater system. The cable can be made of cheap plastic or higher grade optical strands. The connectors do not lock to the components, like an AES/EBU cable, nor are they as secure as a S/PDIF digital cable.

A digital optical cable transmits digital signals as on/off pulses of red light that go between the components. The light itself is a basic LED light, not a laser light. Optical cables are immune to the effects of Radio Frequency Interference (RFI) and Electromagnetic interference (EMI). However, to ensure good performance, the cable must have a bandwidth of 9MHz, and it is better to have 11MHz. The cables are limited to runs of no more than five meters, though in theory the cables can go to 10 meters. Longer runs need signal boosters to work.

Digital optical cables are best constructed of multiple, small diameter (less than 200 micrometers) fibers, rather than a single strand. The connectors themselves should be well polished, and the cable should be round. Finally, the cable will not work if it is bent; it can be curved, but it can't have a sharp kink in it and still work.