What is Dark Fibre?
In its most basic form, fibre optic cabling is a glass conductor between a transmitter (laser beam) and a receiver. The electronic signals are changed to pulses of light for the laser to transmit, the receiver then collects these pulses of light and converts them back into electronic signals.
The unused cores, which have no electronic devices attached at either end, have been given the name dark fibre in reference to its ‘unlit’ state.
So why are they there? It could be one of two reasons: depending on the installation method used, the cost of installation of fibre optic cable can be four times or more the cost of the cable and terminations. For this reason some people prefer to install more cores or cabling than they require, with the expectation that there demand will increase in the future. It could also be for the event of failure of active cores.