Structure Cabling Solutions

Fiber Optic Cable 101

Fiber optics are a buzzword we hear quite frequently in the telecommunications world. You may even see signs in your neighborhood warning of buried fiber optic cable. Here we will go into what fiber optic cabling is and what its features are.

What is a fiber optic cable?fiber optic cable

Fiber optics, also called optical fibers, are long strands of drawn glass that are about as thick as a piece of human hair. These thin strands are grouped together into bundles called optical cables. Their job is to transmit light signals, which can travel at very long distances. At the point of origination, the light signals are encoded with data – any data, like what you are looking at on this screen right now. The light travels along the optical cables at a very high speed and is received at the other end.

These cables were originally created in the 1950s for endoscopes, which help doctors see the inside of a patient without doing major surgery. In the 1960’s telephone engineers figured out how to use this technology to transmit phone calls.

How do fiber optic cables work?

Fiber optic cables are composed of long, thin strands of glass which are reflective. Light travels down these strands by bouncing off the walls repeatedly. Each light particle (photon) is bouncing down a mirror-like pipe until it reaches the end of the cable.

Types of Fiber Optic CableClose-up of technician checking routers in server room

There are multiple types of fiber optic cables. These are generally combined in different ways, depending on the purpose for the cable.

Single and Multimode Fiber

Single mode fiber is the simplest type of fiber optic cable. The core of this type of cable is very thin so the signals travel straight down the middle without bouncing off of the edges. This type of cable is generally used for Internet, telephone applications and the single mode fibers are grouped into a bundle.

Multimode fiber is about 10x as large as a single mode cable. Light beams travel through the core following different paths or different modes. This type of cable is only designed to send data short distances, so it is used for interconnecting computer networks.


In some cases, there are flame and toxicity requirements for installation of cable. Plenum cables are compliant for installation in air plenums, which are the parts of the building facilitating heating and cooling. This type of cable uses specific materials in the “jacket,” which is the coating that protects the cabling from moisture, heat or flame.

Simplex and Duplex Optical Fiber

Simplex fiber optic cables contain a single strand of thing glass. This type of cable is used where a single transmission is required between devices or when a multiplex data signal is used (bi-directional communication over one fiber).

A duplex fiber optic cable has two strands of glass. This type of cable is used where a separate transmit and receive are required.


    • Siamese structures – two cables are placed side by side, each with their own jacket.
    • Hybrid cables – fiber optics combined with copper cables
    • Bundled and composite cable – fiber optic, copper, and even power pair cables are combined

Fiber Optics are used for computer networking, broadcasting, medical scanning, and military equipment. We have fiber optic connectivity in our homes, office buildings, restaurants, and pretty much every urban location with an internet connection. If you would like to learn more about fiber optic cabling, contact us at 763-475-5500 or email


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