FOA CFOS/L key terms

A thin strand of glass or plastic that carries information as pulses of light. It consists of a core surrounded by cladding and a protective coating.

The central light-guiding region of a fiber. Its diameter and refractive index profile determine how many modes the fiber supports and how tightly light is confined.

The glass layer surrounding the core with a slightly lower refractive index. This index difference keeps light inside the core through total internal reflection.

The mechanism that guides light along a fiber. Light striking the core-cladding boundary above the critical angle reflects back into the core instead of refracting out.

A dimensionless number describing the range of angles over which a fiber accepts light. Higher values capture more light but are associated with greater modal dispersion in multimode fiber.

The maximum half-angle, measured from the fiber axis, at which incoming light is guided by the core. It is directly related to the fiber's numerical aperture.

Fiber with a small core, typically around 8 to 10 micrometers, that supports only one propagation path. It offers the lowest loss and highest bandwidth over long distances.

Fiber with a larger core, commonly 50 or 62.5 micrometers, that carries many light paths simultaneously. It suits shorter links such as within buildings and data centers.

The diameter of the light intensity distribution in a single-mode fiber, slightly larger than the physical core. Mismatches between linked fibers cause splice and connector loss.

Pulse spreading caused by different modes traveling at different speeds through a multimode fiber. It limits bandwidth and distance, and is reduced by graded-index core profiles.

Pulse spreading because different wavelengths travel at slightly different speeds through glass. It matters most on long single-mode links and is managed by fiber choice and transceiver design.

The loss of optical power as light travels along a fiber, expressed in decibels per kilometer. It comes from absorption, scattering, and bending, and varies with wavelength.

A band of wavelengths where fiber loss is relatively low and equipment commonly operates, such as 850, 1300, 1310, and 1550 nanometers. Choice depends on fiber type and reach.

A logarithmic unit used to express ratios of optical power, such as loss or gain. In fiber work, a 3 dB change corresponds to roughly doubling or halving power.

The portion of a premises cabling system that connects entrance facilities, equipment rooms, and telecommunications rooms across a building or campus. It usually uses high-fiber-count cables.

Cabling that runs from a telecommunications room to individual work areas, typically through ceiling or floor pathways. It is limited in length and usually terminated in outlets.

A dedicated space housing cross-connects, patch panels, and active equipment serving a floor or area. It is the distribution point between backbone and horizontal cabling.

The space where external carrier cables enter a building and connect to premises cabling. It includes protection, grounding, and the demarcation point.

A location in horizontal cabling where a multi-user cable is split into individual work area connections, such as in open-plan offices. It must remain accessible and documented.

The fixed connector, often a duplex fiber adapter in a wall plate or floor box, where horizontal cabling ends and the user's patch cord begins.

A rack-mounted assembly of adapters where incoming cables are terminated and cross-connections are made. It organizes the cable plant and simplifies moves, adds, and changes.

A junction where cabling is interconnected using patch cords or jumpers, allowing circuits to be rearranged without recabling. It may be in a room or at the main distribution area.

A short, flexible cable with connectors on both ends used to link equipment, panels, or outlets. Its length, connector type, and polarity must match the installed plant.

A cable construction where each fiber has a protective plastic layer applied directly over it. It is flexible and suited to indoor patch cords and short runs.

A cable design where fibers sit loosely inside gel-filled or dry tubes within a jacket. It protects fibers from moisture and strain and is common in outdoor and backbone installations.

A cable rated for vertical runs between floors in a building. Its jacket limits flame spread but does not provide the full plenum rating required for air-handling spaces.

A cable with a jacket and materials rated for installation in air-handling ducts and plenums. It produces limited smoke and low toxicity when burned and is often more expensive.

Cable wrapped in a metal tape or interlocking sheath to resist rodents, crushing, and abrasion. It is used in harsh pathways and may need grounding depending on construction.

A field-installable or factory-terminated device at a cable end that mates with an adapter to join fibers. Common styles include LC, SC, and ST, each with distinct ferrule sizes.

The small, precisely bored cylinder, usually ceramic, that holds and aligns a fiber end inside a connector. Its endface geometry and polish quality strongly affect loss and reflection.

An endface finish where fiber cores are pressed together under spring force to eliminate the air gap. Variants include PC, UPC, and APC, with APC using an angled finish.

A receptacle that aligns and holds two connectors together, such as a duplex LC or SC adapter. It may include a split sleeve and is mounted in panels or outlets.

The consistent arrangement of transmit and receive paths through a link so that a signal reaches the correct detector. Methods A, B, and C define how duplex or array connections are wired.

A multi-fiber push-on connector holding 8, 12, or more fibers in one ferrule. It enables high-density array connections and requires careful keying and polarity management.

The minimum curve a cable or fiber may be subjected to without added loss or damage. It is specified for installation and long-term use, and bend-insensitive fiber allows tighter bends.

The longitudinal force applied while installing cable. Exceeding the manufacturer's limit can stretch fibers, causing permanent loss or breakage, so pull tension must be monitored.

A flexible or rigid subduct placed inside a larger conduit or pathway to separate and protect cables. It allows later cable additions and helps control bend radius.

Examination of a connector's polished tip with a microscope or automated analyzer to find scratches, pits, and contamination. It is done before mating and after cleaning.

Removing dust, oil, and residue from connector endfaces and adapters using approved tools and lint-free materials. Clean endfaces prevent loss, reflection, and permanent damage from mating.

The reduction in optical power caused by inserting a component such as a connector, splice, or cable into a link. It is measured in decibels and compared against a budget.

A measure of how much light is reflected back toward the source at a connector or splice, expressed in decibels. Higher values mean weaker reflection and better performance.

The maximum allowable total loss for a link, calculated from fiber attenuation, connector and splice losses, and margins. Measured loss must not exceed this value for the system to work.

A test instrument that sends light pulses and analyzes reflections to locate faults, measure loss, and report distance along a fiber. It is used for troubleshooting and acceptance testing.

A measurement of total end-to-end loss using a light source and power meter or an optical loss test set. Results are compared with the calculated loss budget for acceptance.

A standardized setup for loss testing that defines how launch and receive cords and connections are arranged. Using one method consistently keeps results comparable and fair.

A standardized, hierarchical approach to premises wiring that separates backbone, horizontal, and work area elements. It supports multiple services and simplifies changes and documentation.

The records and labeling that document a cabling system, including identifiers, pathways, and connectivity. Good administration speeds troubleshooting and supports moves, adds, and changes.

A drawing updated to show the cabling and pathways as actually installed, including deviations from the design. It is a key handover document for the owner.

A table listing each cable's identifier, endpoints, type, length, and test status. It ties physical installation to documentation and helps verify completeness at handover.