dark fiber

Dark fiber is a laid but unused optical fiber that can be rented by users for their own needs. The name dark fiber comes from the fact that no light pulses are transmitted over the unused optical fiber.

Dark fibers have no infrastructure and are offered by providers for backbones, for local area networks( LAN), the access area and the wide area. To use dark fiber, customers must equip it with the appropriate infrastructure, i.e., optical components and optical network nodes such as optical switches, optical add/drop multiplexers and optical amplifiers.

Often, dark fiber is installed directly by utilities when laying power cables. A dark fiber is laid between two locations without any service and can be used as a point-to-point connection. The tenant must install his own infrastructure and set up and update his own services. He has the advantage that he can use the dark fiber exclusively and make full use of the available bandwidth with wavelength division multiplexing. No other user can access it. To ensure continued operation in the event of a fiber optic cable failure, dark fibers are installed with redundant fiber optic cables.

The costs for dark fiber do not depend on the bandwidth used, the volume of data transmitted or the data transfer rate. They are determined by competition and by the work required to lay the optical fibers. In addition, the costs are concerned with the contract term, the route length and the number of optical fibers in the dark fiber. From a cost perspective, the concept is an interesting alternative for connecting branch offices to corporate headquarters or for connecting a data center.