Demystifying Fiber Terminology

It’s common when a community is getting fiber to have the engineers tossing around technical terms that a layperson is not going to understand. Today’s blog will try to demystify the more common fiber terminology that you’ll likely hear.

Absorption: This is the phenomenon where the natural impurities in glass absorb some of the light signal inside of a fiber path.

ADSS (all-dielectric self-supporting). This is a hardened fiber cable that can be hung directly without a supporting messenger wire. This is primarily used for hanging fiber near electric wires (avoids have a metal wire near to the power lines).

Attenuation: This is a term that defines the amount of light that is lost during a fiber transmission due to absorption and scattering. Attenuation is usually measured in decibels (dB) per kilometer.

Attenuator: This is a device that is used to purposefully reduce signal power in a fiber optic link.

 Back Reflection (BR) refers to any situation that causes the light signal inside fiber to change direction. The most common form of back reflection happens when there is an interface between a lit fiber and air.

Buffer: This is the protective outer layer of material that is in direct contact with the fiber. Manufacturers offer a wide range of different buffering materials.

Insertion Loss: This describes the phenomenon where the light signal gets interrupted and diminished when the light signal encounters a fiber splice point or some electronic component in the network.

Messenger. This refers to a galvanized steel cable that is strung between poles and which is used to support fiber cable.

Multimode: This is a fiber that is capable of transmitting multiple wavelengths of light. Multimode fibers are larger than other fiber and come in two typical sizes – 50µm (microns) or 62.5 µm, compared to 2µm to 9µm for single-mode fiber. Multimode fiber is most commonly used for short transmission distances.

Return Loss: This measures the amount of light that completes the path through a fiber, expressed in decibels. The higher the return loss, the better.

Scattering: This is the other primary reason for signal loss in a fiber (along with absorption). Scattering occurs when light collides with small particles in the fiber path.

Single Mode: This is a fiber with a small fiber core size of 8-10 µm (microns). This fiber is used to transmit a single wavelength for long distances at high speeds.

Wavelength: This is a measure of the frequency (color) of light, expressed in microns or nanometers. The most typical wavelengths used in fiber cables are 850nm, 1300nm, and 1350nm.

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