Every join between two fibers costs a little light. Connectors let you plug and unplug; splices fuse fiber for good. Here are the joints that hold a network together — and how to keep their loss low.
No join is perfect. A little light is lost crossing it (insertion loss, in dB) and a little bounces straight back toward the source (return loss / reflectance). Low insertion loss keeps the budget healthy; low reflection keeps lasers and high-speed links stable.
Connectors hold two ferrules face to face so the cores line up. LC and SC are the common singles; MPO/MTP packs many fibers in one. The polish matters too: a flat UPC endface reflects more, while an angled APC (8°) throws reflections into the cladding — essential for TV and long links.
To join fiber permanently you splice it. A fusion splice welds the glass with an electric arc for the lowest loss and reflection. A mechanical splice clamps the two ends in alignment with index-matching gel — faster in the field, but a little more loss.
Arc-welded · ~0.02–0.1 dB · permanent
Aligned + gel · ~0.1–0.5 dB · quick
The Fiber Optic Lab turns these concepts into hands-on instruments you can practise safely — no fragile fiber, no costly gear. Log in to the suite to try them.
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