FOA CFOS/S flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Fusion splice typical loss

A well-made single-mode fusion splice typically shows 0.02 to 0.10 dB loss, measured bidirectionally with an OTDR; values above the project threshold should be re-spliced.

Cleave angle tolerance

Single-mode cleaves should be within about 0.5 degrees of perpendicular; larger angles increase splice loss and may cause the splicer to reject the fiber before arcing.

Core alignment splicer

A splicer that images the fiber core and aligns it directly, typically achieving mean splice loss of 0.05 dB or better on single-mode fiber.

Cladding alignment splicer

A splicer that aligns fibers by their outside cladding diameter rather than the core, generally producing slightly higher loss than core alignment, roughly 0.05 to 0.15 dB.

Arc power setting

The electric current and duration used to fuse fibers; set per fiber type because single-mode, multimode, and bend-insensitive fibers need different arc energy to avoid high loss.

Splice protector heat shrink

A sleeve with a steel strength member placed over the bare splice and cured in the splicer heater; it protects the joint from bending and moisture after splicing.

Strip length for splicing

The coating removal length, commonly 25 to 40 mm depending on the splice protector, must match the protector and cleaver so the bare fiber and splice sit correctly.

Cleaning before cleaving

Bare fiber is wiped with lint-free wipes and 99 percent isopropyl alcohol to remove coating residue; contamination causes arc instability and elevated splice loss.

Bidirectional OTDR splice loss

True splice loss is the average of measurements from both directions, because backscatter differences between fibers create apparent gainers or losers on a one-way trace.

Gainer on OTDR trace

An apparent negative loss at a splice caused by the downstream fiber having higher backscatter; it does not mean the splice has gain and must be averaged bidirectionally.

Splice loss budget

Total link loss equals fiber attenuation plus connector losses plus splice losses plus margin; each splice count is multiplied by its allowed per-splice loss.

Mechanical splice loss

A mechanical splice uses an index-matching gel and alignment fixture instead of an arc; typical loss is 0.10 to 0.50 dB, higher than a good fusion splice.

Fiber shard disposal

Cleaved fiber scraps must go into a labeled sharps container, never a trash can or floor, because they can penetrate skin and are difficult to see.

Visual fault locator use

A VFL injects visible red light to locate breaks, bends, and bad splices; never view the fiber end directly while the VFL is active.

Splice acceptance threshold

A project-specified maximum loss per splice, commonly 0.10 dB single-mode outside plant or 0.30 dB multimode premises; exceeding it requires re-splicing.

Mode field diameter mismatch

Splicing fibers with different mode field diameters, such as standard and bend-insensitive single-mode, increases loss; the splicer arc and loss estimate should be adjusted.

Multimode splice arc settings

Multimode fibers generally require different arc current and time than single-mode; using single-mode settings can cause excessive melting and higher splice loss.

Splice loss estimation accuracy

The splicer's estimated loss is based on alignment images and is approximate; final acceptance should rely on OTDR or power meter measurements, not the splicer display alone.

Fiber coating strip tool

A stripping tool removes the protective coating without nicking the glass; nicks cause fiber breaks and must be avoided by using the correct blade size.

Cleaver blade maintenance

A dull or misaligned cleaver blade produces hackled or angled ends; blade rotation and replacement per manufacturer intervals keep cleave quality within tolerance.

Arc test before splicing

An arc calibration or test fire checks arc stability and position; unstable arcs cause bubbles, necking, or high-loss splices and should be corrected first.

Splice tray bend radius

Splices are stored in trays that maintain a minimum bend radius, typically 30 mm or more, to prevent macrobend loss and long-term fiber damage.

OTDR dead zone

The distance after a reflective event where the OTDR cannot measure; splices near connectors may be hidden in the dead zone and need testing from the other end.

Fusion splice bubble defect

A bubble or void in the fused joint from contamination or wrong arc energy raises loss and weakens the splice; it should be re-spliced.

Splice loss averaging formula

True splice loss in dB equals half the sum of the two directional OTDR readings, for example (0.15 + 0.05) / 2 = 0.10 dB.

Ribbon fiber splicing

Mass fusion splicers join multiple fibers at once, typically 12-fiber ribbons; alignment and cleave quality across the ribbon determine overall splice loss.

Splice documentation record

Each splice should be recorded with location, fiber identification, date, splicer settings, and measured loss, supporting acceptance and future troubleshooting.

Index matching gel

A gel used in mechanical splices to reduce Fresnel reflection and loss by matching the refractive index between fiber ends; it can degrade over time.

Fresnel reflection at splice

An air gap or poor contact at a splice causes back reflection; fusion splicing eliminates the gap and minimizes reflection, important for analog and high-speed systems.

Splice loss vs wavelength

Splice loss is generally measured at 1310 and 1550 nm for single-mode; loss can differ by wavelength, so acceptance testing should specify the test wavelength.

Bend-insensitive fiber splicing

Bend-insensitive single-mode fiber often needs reduced arc current and careful alignment because its mode field and cladding structure differ from standard fiber.

Splice rework decision

A splice is reworked when measured loss exceeds threshold, when the splicer reports a fault, or when visual inspection shows bubbles, misalignment, or incomplete fusion.