Splicing, Termination, and Connectorization
Fusion splicing
Fusion splicing fuses two cleaved end faces with an electric arc. Quality depends on a good cleave (typically under 0.5° end angle, correct cleave length for the holder) and clean fiber. Typical splice loss is about 0.1–0.2 dB for fusion; the estimator will reject a poor cleave outright. Always protect the splice with a splice protector sleeve and lay it in the tray at or above the tray's minimum bend radius. Mechanical splices use index-matching gel and typically run 0.2–0.5 dB; they are fine for restoration but are not preferred for permanent high-count installations.
Connectorization methods
Field-installable connectors fall into three families: epoxy-and-polish, pre-polished/pre-terminated (with index-matching gel and a mechanical interface), and splice-on connectors (a factory ferrule with a short fiber stub fusion-spliced in the field). Pigtails - factory-terminated fiber stubs - are spliced onto the incoming cable, giving factory-grade end faces with one splice per fiber.
End-face quality and cleaning
Inspect every end face with a scope; the acceptance criteria come from IEC 61300-3-35, which defines zones (core, cladding, adhesive, contact) and allowable scratches and defects per zone. The field rule is inspect, clean, inspect: dry clean, then a lint-free wipe with approved solvent if needed, then re-inspect. A single speck of dust can add several dB and destroy a connector's ferrule.
Polishing and mating
PC/UPC give a domed physical contact; APC is angled 8° for lower reflectance (about −60 dB vs about −50 dB for UPC) and is used with splitters and CATV/RFoG optics. Never mate an APC to a UPC - the air gap produces high loss and back-reflection.
Worked example
A 24-fiber trunk to pigtails: 24 fusion splices at 0.1 dB = 2.4 dB - a number no single splice shows but that a whole-link budget must accommodate.