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What Is Fusion Splicing?

Fusion splicing is the process of permanently joining two optical fibers by precisely aligning the glass cores and melting them together with a controlled electric arc. The result is a single continuous strand of glass — the light travels straight through with almost no loss.

Open core-alignment fusion splicer with two bare optical fibers seated in the V-grooves and the alignment view shown on the splicer screen. — Fusion splicer joining two fibersFuture media: high-res splicer screen showing fiber alignment.

Fiber is spliced anywhere a continuous run isn't possible — at handholes, vaults, aerial enclosures, splitter cabinets, network huts, and customer-side terminations. Splicing is what stitches a network together.

[ Mechanical Splice ]

Quick · Temporary

Two fibers are clamped together inside a small alignment sleeve with index-matching gel. Fast for emergency repairs, but typically introduces 0.1–0.5 dB of loss and degrades over time.

[ Fusion Splice ]

Permanent · Industry Standard

Cores are fused with an electric arc into a single strand. Typical loss is 0.01–0.05 dB and the splice lasts the lifetime of the cable. This is what nearly every modern build uses.

[ Knowledge Check ]

Why is fusion splicing the industry standard over mechanical splicing?

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