The portion of optical attenuation in which light signal is absorbed into the glass during transmission. This occurs during the conversion of optical power to heat and is caused by impurities in the fiber such as hydroxyl ions

A/B Switch

A device that accepts inputs (optical or electrical) from a primary path and a secondary path to provide automatic or manual switching in the event that the primary path signal is broken or otherwise disrupted. In optical A/B switches, optical signal power thresholds dictate whether the primary path is functioning and signals a switch to the secondary path until optical power is restored to the primary path


An Adapter is a mechanical device designed to align fiber-optic connectors. It contains the split sleeve, also known as the interconnect sleeve, that holds the two ferrules together. Adapters can help mate or connect a variety of Fiber optic cables together. Fiber optic adapters are also known as mating sleeves, couplers, and mating adapters. A Fiber Optic Adapter Panel is a good example of this.


Loss of transmission power in both RF and light over distance traveled. Attenuation is measured in dB loss per length of cable. It is usually caused by absorption and scattering. In the example of light, attenuation can be mitigated or boosted by using an EDFA (short for erbium-doped fiber amplifier).


A passive device for reducing the amplitude of a signal without appreciably distorting the waveform. Multicom’s Fiber Optic Attenuators fit in all standard panel interfaces including Adapter Panels.

Back Reflection

A term applied to any process in a cable plant that causes light to change directions in a fiber and return to the source. This most commonly occurs at a connector’s interface where a glass-air interface causes a reflection. A good introduction to intricacies of fiber optic cable, cable designs and cable types is in the Multicom Fiber Optic Technical Resource Guide.


The information carrying capacity of the system. In Analog systems, this is also the highest Frequency that can be carried. The range of signal frequencies that a fiber optic cable or equipment will transmit. As an example, a Multicom 1550 Transmitter takes 45-1000MHz RF input bandwidth and transmits that signal at 6 or 10dBm output power over the 1550nm bandwidth.

Buffer Coating

Plastic coating that protects the fiber from damage and moisture

Cable Plant

All the optical elements between a transmitter and a receiver


Glass covering surrounding the core that acts as a mirror to reflect light back into the core


Thin glass or plastic center of the fiber in which light is transmitted through. The larger the core, the more light that can pass through


Short for Erbium-Doped Fiber Amplifier. EDFA is an optical repeater device that is used to boost the intensity of optical signals being carried through a fiber optic communications system. An optical fiber is doped with the rare earth element erbium so that the glass fiber can absorb light at one frequency and emit light at another frequency.

FTTx (Fiber To The X)

Most commonly covers FTTh (Fiber To The Home), FTTc (Fiber To The curb), FTTp (Fiber To The Premises), and FTTd (Fiber To The Desk) applications running from the central office or head-end to business, residential, or multi-unit dwellings.

  • FTTh – Indicates fiber network connections running from the central office to a residence, or very small multi-unit dwelling.
  • FTTc  – Indicates fiber network connections to a network enclosure located at, or near, a property street/curb location, from which copper based networks generally connect to the end user
  • FTTp – Is used for business, commercial, and institutional applications where fiber network connection(s) are distributed to a campus, set of structures, or high density building with a centrally located network operations center.
  • FTTd – Indicates applications where a fiber optic connections are distributed from the central office to individual work stations or computers inside a structure, dwelling, or building.

FTTx applications require a wide range of products from multi-fiber trunk cables to standard simplex cable assemblies, and most everything in between. Multicom makes a number of products supporting FTTx requirements from central office all the way to the subscriber location.


A component (usually a rigid tube) used to align and protect the stripped end of a fiber

Fusion Splicer

An instrument that splices (joins) fibers by fusing or welding them together typically by electrical arc


Gigabit Passive Optical Network

Jumper Cable

a short single fiber cable with connectors on both ends used for interconnecting other cables or testing


The entire span between two optical devices. Includes all cable, connections and splices

Loss Budget

The maximum amount of power that is allowed to be lost per optical link


Type of fiber optic cable in which the diametral core is considerably larger than the wavelength of light traveling through it allowing for multiple modes of light to propagate. Two types used are 50/125µm and 62.5/125µm


A short optical fiber permanently attached to a source, detector, or other fiber optic device at one end and an optical connector at the other


Converts optical signal into electrical signal

Return Loss

The ratio of the power launched into a cable and the power of light returned down the fiber. This measurement is expressed in positive decibel units (dB). A higher number is better. Return Loss = 10 log (incident power/returned power)


A second cause of attenuation. Scattering occurs when light collides with individual atoms in the glass.


Type of fiber in which the diametral core allows for only one mode of light to propagate. One type used is 9/125µm


Combines light signals and splits them out over single or multiple outputs

Tensile Strength

Stress at which a material breaks or permanently deforms

Total Internal Reflection

The reflection that occurs when light strikes an interface at an angle of incidence greater than the critical angle.


Converts electrical signals into optical and transmits the optical signals into the optical fiber


A means of measuring light color. Expressed in nanometers (nm).