PM Coupler

Fiber Optic Glossary

Fiber Optic Glossary

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.


Access Network

Part of the telecommunication network that connects to individual and corporate users.


Active Device

A device that requires a source of energy for its operation and has an output that is a function of present and past input signals. Examples include controlled power supplies, transistors, LEDs, amplifiers, and transmitters.



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.


Adapter Sleeve

A mechanical fixture within an adapter body that aligns and holds two terminated fiber connectors. Adapter sleeve material is typically phosphor bronze, ceramic or polymer


Add/Drop Multiplexing

A multiplexing function offered in connection with SONET that allows lower level signals to be added or dropped from a high-speed optical carrier in a wire center. The connection to the add/drop multiplexer is via a channel to a central office port at a specific digital speed (DS3, DS1, etc.)


Add-drop multiplexer

A device that drops and/or add one or more optical channels to a signal.



Abbreviation for add-drop multiplexer. A device which adds or drops signals from a communications network.



A device, inserted within a transmission path, that boosts the strength of an electronic or optical signal. Amplifiers may be placed just after the transmitter (power booster), at a distance between the transmitter and the receiver (in-line amplifier), or just before the receiver (preamplifier).


Angular Misalignment

Loss at a connector due to fiber end face angles being misaligned.


APC (Angled Physical Contact)

Abbreviation for angled physical contact. A style of fiber optic connector with a 5°-15° angle on the connector tip for the minimum possible backreflection.


Aramid Yarn

Yellow fibers that provide cable tensile strength, support, and additional protection for the optical fiber bundle. Kevlar® is a particular brand of aramid yarn.


ASE (Amplified Spontaneous Emission)

A background noise mechanism common to all types of erbium-doped fiber amplifiers (EDFAs). It contributes to the noise figure of the EDFA which causes loss of signal-to-noise ratio (SNR).



Reduction of signal magnitude, or loss, normally measured in decibels. Fiber attenuation is normally measured per unit length in decibels per kilometer. The decrease in signal strength along a fiber optic waveguide caused by absorption and scattering. Attenuation is usually expressed in dB/km.



In electrical systems, a usually passive network for reducing the amplitude of a signal without appreciably distorting the waveform. 2) In optical systems, a passive device for reducing the amplitude of a signal without appreciably distorting the waveform.


CATV Amplifier

A RF power amplifier is a type of electronic amplifier used to convert a low-power radio-frequency signal into a larger signal of significant power, typically for driving the antenna of a transmitter. It is usually optimized to have high efficiency, high P1dB compression, good return loss on the input and output, good gain, and good heat dissipation.



EDFA is the abbreviation of erbium-doped fiber amplifier. It is a kind of laser amplifier and it is the most deployed fiber amplifier as its amplification window coincides with the third transmission window of silica-based optical fiber. EDFAs have two commonly-used pumping bands - 980 nm and 1480 nm. The 980 nm band has a higher absorption cross-section and is generally used where low-noise performance is required. The absorption band is relatively narrow and so wavelength stabilized laser sources are typically needed. The 1480 nm band has a lower, but broader, absorption cross-section and is generally used for higher power amplifiers. A combination of 980 nm and 1480 nm pumping is generally utilized in amplifiers.


Ethernet Switch

A switch is a mechanical device used to connect and disconnect a circuit at will. Switches cover a wide range of types, from subminiature up to industrial plant switching megawatts of power on high voltage distribution lines.


Fiber Optic Adaptor

An adaptor is a device used to connect the same or different type connectors, so that a connection may be made between them.


Fiber Optic Cable

An fiber optic cable is a cable containing one or more optical fibers. The optical fiber elements are typically individually coated with plastic layers and contained in a protective tube suitable for the environment where the cable will be deployed.


Fiber Optic Patch Cord

A patch cord is an optical cable, used to connect optical device to another for signal routing. Each end of the cable is attached to a connector, so the cord may be plugged in.


Fiber Optic Pigtail

A pigtail is a cable with one connector. Types of connectors may vary widely, FC, SC, ST, and etc.



Fiber to the x (FTTX) including FTTH, FTTB, FTTC and FTTN, is a generic term for any network architecture that uses optical fiber to replace all or part of the usual copper local loop used for telecommunications. FTTx is delivered using active Ethernet and various passive optical network (PON) technologies. The passive FTTx approach utilizes equipment that does not require power, and splits or divides the bandwidth between users.



Gigabit Ethernet Passive Optical Network(GEPON) is a point-to-multipoint, fiber to the premises network architecture in which unpowered optical splitters are used to enable a single optical fiber to serve multiple premises, typically 32.


Insertion Loss

Insertion loss is the loss of signal power resulting from the insertion of a device in a transmission line or optical fiber and is usually expressed in dBs.

The total Optical Power Loss caused by the insertion of a component such as a Splice or Connector  in an optical Fiber system.

Insertion loss from Absorption Insertion loss from misalignment- either from mismatched Core diameters or from lateral misalignment Insertion loss from an air gap. This occurs from no physical contact. The degree of loss is not as severe,however, with loss typically less than 0.5dB. Insertion loss from contamination. Contamination is the most common cause of insertion loss, such as dirt, scratches, or chips. See Attenuation. See Optical Loss. See Intrinsic Loss. See Gap Loss.



Local Area Network (LAN) is a computer network covering a small geographic area, like a home, office, or group of buildings e.g. a school. The defining characteristics of LANs, in contrast to wide-area networks (WANs), include their much higher data-transfer rates, smaller geographic range, and lack of a need for leased telecommunication lines.



A fiber laser is a laser in which the active gain medium is an optical fiber doped with rare-earth elements such as erbium, ytterbium, neodymium, dysprosium, praseodymium, and thulium. They are related to doped fiber amplifiers, which provide light amplification without lasing. Fiber nonlinearities, such as stimulated Raman scattering or four-wave mixing can also provide gain and thus serve as gain media for a fiber laser.


Optical Attenuator

An optical attenuator is a device used to reduce the power level of an optical signal, either in free space or in an optical fiber. They are commonly used in fiber optic communications. The basic types of optical attenuators are fixed, step-wise variable, and continuously variable.


Optical Coupler

Optical coupler is passive optical device that connects three or more fiber ends, dividing one input between two or more outputs, or combining two or more inputs into one output. Optical coupler is generally deployed in passive optical network.


Optical Receiver

The main component of an optical receiver is a photodetector that converts light into electricity through the photoelectric effect. The photodetector is typically a semiconductor-based photodiode, such as a p-n photodiode, a p-i-n photodiode, or an avalanche photodiode. Metal-semiconductor-metal (MSM) photodetectors are also used due to their suitability for circuit integration in regenerators and wavelength-division multiplexers.


Optical Transmitter

The most commonly-used optical transmitters are semiconductor devices such as light-emitting diodes (LEDs) and laser diodes. The difference between LEDs and laser diodes is that LEDs produce incoherent light, while laser diodes produce coherent light. For use in optical communications, semiconductor optical transmitters must be designed to be compact, efficient, and reliable, while operating in an optimal wavelength range, and directly modulated at high frequencies.



Router, including broadband and wireless router, is a device whose software and hardware are usually tailored to the tasks of routing and forwarding information. It is used to connect two or more logical subnets, which do not necessarily map one-to-one to the physical interfaces of the router



Synchronous digital hierarchy (SDH) and synchronous optical network (SONET) based on circuit mode communication, meaning that each connection achieves a constant bit rate and delay refer to a group of fiber-optic transmission rates that can transport digital signals with different capacities.



Wavelength-division multiplexing (WDM) is a technology which multiplexes multiple optical carrier signals on a single optical fiber by using different wavelengths of laser light to carry different signals. This allows for a multiplication in capacity, in addition to enabling bidirectional communications over one fiber.



A wireless LAN( WLAN) is a wireless local area network, which is the linking of two or more computers without using wires. WLAN utilizes spread-spectrum or OFDM modulation technology based on radio waves to enable communication between devices in a limited area, also known as the basic service set. This gives users the mobility to move around within a broad coverage area and still be connected to the network.


DK Photonics

high power isolator