FOA CFOS/H key terms

A hair-thin strand of glass or plastic that carries information as pulses of light, consisting of a light-guiding core surrounded by cladding that reflects light back into the core.

The central light-carrying region of an optical fiber, made of doped glass with a higher refractive index than the surrounding cladding; its diameter determines how many modes the fiber supports.

The glass layer surrounding the fiber core with a slightly lower refractive index, which confines light to the core through total internal reflection and provides mechanical protection for the light-guiding surface.

The optical effect in which light striking the core-cladding boundary at a shallow enough angle is reflected entirely back into the core instead of refracting out, keeping the signal traveling along the fiber.

A measure of the range of angles from which light can enter a fiber and still be guided, derived from the refractive indices of core and cladding; larger values accept light more readily but allow more modal spread.

Fiber with a very small core, typically around 8 to 10 micrometers, that carries only one propagation path; used for long distances and high bandwidth, and standard for most residential drop and in-home backbone runs.

Fiber with a larger core, commonly 50 or 62.5 micrometers, that supports many light paths at once; cheaper to connectorize but limited in reach and bandwidth by modal dispersion.

Pulse spreading caused by different light paths in a multimode fiber arriving at slightly different times, which smears bits together and limits usable distance and data rate.

The loss of optical power as light travels through fiber, connectors, and splices, expressed in decibels; it grows with distance and is the main budget item when planning a link.

The color of light used to carry a signal, measured in nanometers; home and access networks commonly use 1310, 1490, and 1550 nanometers, and different wavelengths can share one fiber.

A technique that sends several independent signals on one fiber at different wavelengths, letting a single strand serve multiple homes or separate upstream and downstream traffic.

Fiber designed with a trench or modified cladding so that tight bends cause far less loss, allowing it to be routed around corners and behind walls in home installations.

A finished assembly in which one or more coated fibers are protected by strength members, a buffer, and an outer jacket so the fiber survives pulling, bending, and the home environment.

Cable in which each fiber is directly surrounded by a snug plastic layer, giving good handling and crush resistance; common for indoor and in-home runs, including drop cable and patch cords.

Cable in which fibers sit loosely inside gel-filled tubes, isolating them from strain and moisture; typical of outdoor plant and often used where a drop transitions from outside to inside.

The outermost protective sheath of a cable, which resists abrasion, moisture, and sunlight and carries flame ratings; indoor jackets are often riser or plenum rated, while outdoor jackets resist ultraviolet light.

A component such as aramid yarn or a rigid rod inside a cable that takes up pulling and bending loads so the glass fibers are not stretched or broken during installation.

A flame-spread classification for cable permitted in vertical shafts between floors of a building, tested so fire does not readily travel up the cable in a riser.

A stricter flame and smoke classification for cable installed in air-handling spaces such as above a suspended ceiling; plenum cable limits smoke and burning material in the air stream.

The cable that runs from the network access point or terminal to the subscriber's premises, usually a small, flexible, often bend-insensitive single-mode cable suitable for aerial, buried, or facade routing.

A field-terminable or factory-finished plug that aligns two fibers so light crosses with minimal loss; common styles in home networks are SC, LC, and ST, each with polish variants.

The precisely drilled cylindrical sleeve inside a connector that holds and centers the bare fiber, typically ceramic; its concentricity and end-face quality dominate connector loss and reflectance.

A connector end-face geometry in which the fiber is domed so two mated ferrules touch directly, eliminating the air gap; variants such as angled physical contact reduce back reflection further.

A field-installed device that aligns and holds two cleaved fibers, often with index-matching gel; fast and tool-light, useful for repairs and for joining pigtails in a home enclosure.

A permanent joint made by melting two cleaved fiber ends together with an electric arc; it gives the lowest loss and highest reliability and is the usual choice at a home's fiber termination point.

A short length of fiber permanently terminated with a factory connector on one end and bare fiber on the other, spliced to the installed cable to provide a high-quality connectorized end.

A short, flexible, factory-terminated cable used to connect equipment, outlets, and patch panels; its connector types and polish must match the ports it joins.

A rack- or wall-mounted housing that terminates incoming cables and presents connectors for flexible patching, keeping permanent cabling organized and protected from repeated handling.

A compartment inside an enclosure that holds and protects spliced fibers, maintaining minimum bend radius and organizing splices so they are not disturbed by later work.

A sealed housing, often used outdoors, that protects splices and slack fiber from water, dust, and mechanical damage, and is usually re-enterable for future changes.

The demarcation box on or near the home where the provider's drop cable ends and the customer's inside wiring begins, often housing the optical termination and sometimes the optical network terminal.

The customer-premises device that converts optical signals from the provider into electrical Ethernet, telephone, and video services for the home; it is the fiber equivalent of a modem.

A provider architecture in which one fiber from the central office is shared among many homes through unpowered optical splitters, with each home's terminal recognized by assigned time slots or wavelengths.

A no-power glass component that divides one incoming fiber's light among several outputs, such as 1 by 8 or 1 by 32; each output receives a fraction of the original power, adding loss to the link budget.

The minimum curve a cable or fiber may be bent without added loss or damage; violating it can crack glass or push light out of the core, so installers keep generous loops and use bend guides.

The maximum force allowed while pulling cable, set by the manufacturer, usually expressed in newtons or pounds; exceeding it stretches or breaks fibers even when the jacket looks intact.

The practice of routing, supporting, labeling, and dressing cables neatly with trays, hooks, and ties so fibers stay within bend limits and future technicians can trace and service them.

Marking both ends and intermediate points of each cable and port with durable, unique identifiers so circuits can be identified during testing, moves, and troubleshooting without guesswork.

A test instrument that sends light pulses down a fiber and plots reflections versus distance, revealing loss, breaks, splices, and connector events along the run so faults can be located.

A calibrated light source and power meter pair used to measure end-to-end loss of a link at a chosen wavelength; the result is compared with the calculated link loss budget to pass or fail it.

The total attenuation a link is allowed to have, computed from fiber loss per kilometer, connector and splice losses, splitter loss, and margins, then compared with measured loss.

The drop in optical power caused by inserting a component such as a connector, splice, or splitter into the path, measured in decibels as the difference between input and output power.

The portion of light reflected back toward the source at a connector or break, expressed in decibels as a negative value; excessive reflection degrades some systems and signals a poor end face.

Examining a connector's polished tip with a microscope or automatic analyzer to find scratches, pits, cracks, and contamination, then cleaning or replacing it before mating.

Removing dust, oil, and residue from ferrules and ports with lint-free wipes and approved solvent or dry cleaners; contamination is a leading cause of high loss and link failure.

A known-good, properly terminated patch cord used to set the zero or reference point on a power meter and to verify that test equipment and adapters are not adding error.

The short distance after a reflective event on a reflectometer trace where the instrument cannot resolve another event; it determines whether closely spaced connectors or splices can be measured separately.

A visible red laser tool coupled to a fiber that makes breaks, tight bends, and bad connectors glow, giving a quick, low-cost way to confirm continuity and find damage near the source.

A calibrated detector that reads received optical power at a chosen wavelength, used to confirm signal levels at the optical network terminal and to check that a link is within operating range.

A systematic process of isolating a fault by checking power levels, cleaning and inspecting connectors, verifying polarity and documentation, and testing sections in turn rather than replacing parts at random.

The boundary between provider-owned and customer-owned cabling and equipment, defining who is responsible for maintenance and where testing responsibilities change hands.

A standards-based layout that organizes cabling into backbone, horizontal, and equipment subsystems with consistent media, connectors, and administration so the network can be maintained and expanded.

A broadband architecture in which optical fiber runs all the way to each living unit, delivering high capacity without the distance limits of copper, typically through a passive optical network.

The final record of what was actually installed, including cable routes, lengths, port assignments, splice details, and test results, used for future moves, adds, and fault finding.

The planned maximum loss for a fiber path, summing fiber attenuation, connector and splice losses, splitter loss, and safety margin, which the design must satisfy and testing must verify.