Cold splicing (mechanical splicing) of optical cables
Mechanical splices align two cleaved fibers in an index-matched channel — no arc, no power. Done correctly they hold 0.1–0.15 dB for years; done sloppily they fail within months. Here is the correct procedure.
- 1
Strip, clean and cleave to spec
Strip 2–3 cm of coating, wipe with IPA, cleave at the length marked on the splice body (usually 10–12 mm). A bad cleave angle (>1°) shows immediately as loss.
- 2
Insert the first fiber to full seat
Push until the fiber bottoms in the V-groove and the coating clamps. A fiber seated short will shift under temperature cycling.
- 3
Close and lock, then insert the second fiber
Same cleave length, push until you feel the fibers meet through the gel. Watch loss on the OTDR/power meter while pressing if available.
- 4
Verify before moving on
Measure with TC-150 power meter + light source or an OTDR. Above 0.3 dB: re-open, re-clean, re-cleave, re-splice — never "leave it, it passes sometimes".
- 5
Stress management
Route the pigtails with ≥30 mm bend radius and secure the splice body so the fibers carry zero tension.
Field tips from TEKCN engineers
- Index-matching gel has a shelf life — discard expired splices rather than trusting them on new projects.
- In cold climates, warm the splice body in an inside pocket before splicing; cold gel does not flow around the fibers.