In summary, fibre optic cables do not use electricity to transmit data; they use light signals. Whether you're linking buildings, running broadband in rural areas, or building 5G infrastructure, the right cable matters. It affects performance, maintenance, cost, and reliability. This. Do I need an armored or dielectric cable? Armor can be applied to a loose tube or ribbon cable for increased mechanical robustness and protection against rodents. A dielectric (metal-free) cable should be. There is no power in the fiber signal just light Most likely, the modem isn't designed to work with fiber, it probably sends out signals on coax or some other more traditional medium. Electronic devices used to generate the light signals being carried by fibre optic cables.