BICSI Installer 2 Fiber key terms

The decrease in optical power as light travels through fiber, connectors, or splices, expressed in decibels. It is caused mainly by absorption and scattering and limits how far a signal can travel.

The optical power lost when a component such as a connector, splice, or cable section is inserted into a link, measured in decibels as the difference between power in and power out.

Pulse spreading in multimode fiber caused by light rays traveling paths of different lengths at different speeds, so they arrive at the receiver at slightly different times and smear the signal.

Pulse spreading caused by different wavelengths from a source traveling at slightly different speeds through the glass. It dominates in single-mode systems and worsens with distance and with wider source spectra.

A number describing the range of angles over which a fiber accepts incoming light. Higher values mean a wider acceptance cone, typically more guided modes, and higher loss in multimode fiber.

Small amounts of light scattered backward along a fiber by microscopic density variations in the glass. An OTDR uses this returned light to measure loss and locate faults.

A wavelength band where fiber loss is relatively low and equipment is standardized, such as 850, 1300, 1310, and 1550 nanometers. Components and test sets must match the window in use.

A multimode fiber rating, given in megahertz-kilometers, showing the bandwidth available over one kilometer. Dividing the rating by the actual link length gives the usable bandwidth at that distance.

A cable design in which each fiber is coated with a protective plastic layer directly against the glass, making it flexible and easy to connectorize for indoor and short-run use.

A cable design in which fibers sit loosely inside a gel-filled plastic tube, isolating them from stress and moisture. It is common in outdoor and long-haul installations with high fiber counts.

Cable built with a metal or dielectric armor layer around the fiber core to resist rodent damage, crushing, and moisture. It is used outdoors, in industrial areas, or where physical protection is needed.

Cable tested and listed for installation in air-handling spaces. It has low flame spread and low smoke production and is usually the most costly jacket option available.

Cable listed for vertical runs between floors, such as in riser shafts. It resists flame travel upward but is not approved for installation in air-handling plenums.

A protective enclosure that houses and seals splices, shielding them from moisture, dust, and physical damage. It is used at aerial, buried, and underground splice points.

A rack- or wall-mounted enclosure holding adapter panels and splice trays, providing an organized place to terminate cables and cross-connect patch cords within a fiber system.

A breakout assembly that splits a multi-fiber cable or ribbon into individually jacketed fibers with standard connectors, giving each fiber mechanical protection and a usable interface.

The longitudinal force applied to a cable during installation. Exceeding the manufacturer's limit stretches or breaks fibers, so tension is monitored with a gauge and kept within specification.

The smallest curve a cable or fiber can tolerate without added loss or permanent damage. It is usually stated as a multiple of cable diameter and enforced during pulling, routing, and coiling.

A flexible or rigid subduct placed inside a conduit or trench to create separate pathways for cables. It eases future pulls and helps separate fiber from power conductors.

A hook-shaped support with a wide, smooth saddle used to hold cables overhead without kinking or over-bending them. Spacing must follow manufacturer and standard requirements.

A compatible compound applied to cable or duct to reduce friction during a pull. Lubricants must be approved for the jacket material and must not leave harmful residue on the fiber.

Extra cable coiled and stored at an enclosure or termination point. It supplies slack for future retermination, splicing, or equipment relocation without pulling new cable.

Joining two fibers by melting their ends together with an electric arc. It gives the lowest-loss, most reliable splice and requires properly cleaved ends, good alignment, and a splice protector.

A splice made by aligning and locking two cleaved fibers inside a small assembly, often using index-matching gel. It is fast and needs no power but usually has higher loss than fusion splicing.

Scoring and breaking a fiber to produce a flat, square endface perpendicular to the core. A good cleave is required for low-loss splicing and for successful connector termination.

A small precision cylindrical tube, usually ceramic, that holds and centers a fiber inside a connector so that it aligns accurately with the mating connector's fiber.

A field-installable connector where epoxy is injected and cured, then the endface is polished. It is durable and low loss but slower, and it requires polishing supplies and technique.

A short length of fiber with a factory-installed connector on one end and bare fiber on the other, spliced onto a cable to provide a finished termination point.

A matched light source and power meter used to measure end-to-end loss of a link at a chosen wavelength. It is the standard instrument for Tier 1 link certification.

An instrument that sends light pulses into a fiber and analyzes returning backscatter and reflections to measure loss, length, and the location of faults along the link.

A known-length reference fiber connected between the OTDR and the link under test, allowing the instrument to measure the first connector and stabilize its receiver before the link's events.

A defined way of connecting source and meter during loss testing, such as the one-jumper or two-jumper method, which determines whether end connectors are included in the measured loss.

The maximum loss a link can tolerate and still operate, calculated from transmitter output, receiver sensitivity, and allowances for repairs and aging. Test results must fall inside this budget.

The distance following a reflective event, such as a connector, during which an OTDR cannot resolve a second event. Shorter pulses shrink dead zones but reduce measurement range.

The portion of light reflected back from a connector, splice, or break, expressed in decibels. High reflectance can disturb transmitters and points to a poor endface or an air gap.

The section of the National Electrical Code covering installation of optical fiber cables and raceways, including which cable types are permitted in plenum, riser, and general-purpose locations.

The standard Steiner tunnel test that measures flame spread and smoke density of cables intended for air-handling spaces; passing it is what qualifies a cable as plenum rated.

A rating system, such as Class 1 or Class 1M, that describes the hazard level of an optical source and the precautions required. Intact fiber systems are typically Class 1.

A document supplied with chemicals such as solvents, adhesives, and lubricants that lists hazards, safe handling, first aid, and disposal requirements for the product.

Updated drawings and records showing the fiber plant as actually installed, including cable routes, splice locations, and test results, used for maintenance and future additions.