What is Dark Fiber?

Dark Fiber (also known as “dark fibre”) refers to fiber-optic cables that are currently installed but are not being used by companies or individuals.

Dark Fiber is also called “unlit fiber,” referring to the fact that these optical cables are not yet activated for use on any network.

The term originally referred to the bandwidth capacity of a given network, but the term itself has come to encompass fiber-optic cables that belong to a network service provider.

“Dark fiber” also refers to someone who has been leased a set of cables but do not own them (called a “lessee”).

Dark fiber is used to help telephone companies or carriers expand their data network, but also exists because it requires a lot of civil engineering and other costs to activate unused fiber-optic cables. One company that has actively sought dark fiber is Google.

Google Hunts for Dark Fiber

Google started its hunt for dark fiber in 2005, when, according to CNET, the Mountain View, California company placed a job ad on the Google’s job site requesting a dark fiber expert: “Google is looking for Strategic Negotiator candidates with experience in…identification, selection, and negotiation of dark fiber contracts both in metropolitan areas and over long distances as part of development of a global backbone network” (Evan Hansen, “Google Wants ‘Dark Fiber'”).

Could Google have been on the hunt for dark fiber as early as January 2005? Yes. Although most companies look for “lit fiber” (cables that are activated already) from telephone companies or those who already own cables in operation, Google sought out unactivated cables.

What could be the purpose? CNET admitted that Google’s decision at the time was not the most budget-friendly:

“The move also raises some tantalizing thoughts, including the long-shot chance that the company is laying the groundwork to jump into the telecommunications business…If Google were to build its own global or national fiber network, the project would likely cost billions of dollars and take years to implement, an investment that would be hard to justify based on the networking needs of most companies. Renting ‘lit’ fiber from carriers is generally a cheaper, and therefore preferred, way to go” (Hansen, “Google”).

Google could only seek dark fiber because of the state of the telecommunications industry. With rising costs to activate dark fiber networks, however, companies like Google could purchase dark fiber in abundance. Dark fiber, once costing $1,200 per mile, has now declined in costs.

Google is not alone in its dark fiber purchases: other companies such as Ford Motor Company, USA Today, Bausch’ Lomb and Gannett Co., as well as Bank of America have purchased their own dark fiber. Since dark fiber was purchased in abundance in the 1990s, dark fiber purchases will likely exist through the first few decades of the twenty-first century.

What is a Dark Fiber Made Of?

Dark Fiber (or dark fibre) is an optical fiber, a thin and light glass or plastic cable that is a little heavier than a human hair. Glass or plastic cables are better sources than metal because metal is a material that can produce electric shock, as opposed to plastic or glass (silica) material, which is less likely to produce electric shock.

The reason why dark fiber is referred to as “fiber-optic” cables is because fiber optics is a scientific field consumed with applying fiber optic cables to telecommunications as we know it. Fiber-optic communication involves the transmission of information over high data speeds — speeds that are higher than most forms of telecommunication. Dark fiber, when activated, will transmit huge amounts of data at high data speeds over longer networks.

Dark Fiber in the News

Ciena, a telecom company located in Linthicum, MD, has created a new optical service delivery platform that enables broadcasting companies to replace their satellite links with dark fiber. To achieve this end, Ciena provided its CN 4200 HD Video Card, which lets broadcaster send HD video over long distances without the need to compress them or lose the HD quality in the process.

One of the benefits of Ciena’s new HD Video Card is that one can perform multiple applications over the same wavelength:

“The CN 4200 enables a variety of applications in a single platform. For example, a production services company can use the CN 4200 to transport HD and SD video plus Gigabit Ethernet (GbE) and Fibre Channel connectivity — all over the same wavelength. It can be deployed in conjunction with other Ciena platforms such as the CoreDirector FS MultiService Optical Switch. This brings advanced switching and protection features and carrier-class service availability to privately managed networks” (Michael Grotticelli, “Replacing satellite links with dark fiber”).

Multitasking is time-saving, and Ciena’s HD video card helps in this endeavor.