Fusion Splicing – What is it, how is it done and why is it used?

Fibre Optic Fusion splicing is the art of welding the ends of two optical fibers together using an electrical arc. The arc is precisely applied to join the two fibers together in such a way that light passing through the fibers are not scattered or reflected back by the splice. This allows the splice and region surrounding it to be as strong or stronger than the original fiber. This is usually a three stage process.

Preparation

preparation
The process of fusion splicing requires both pieces of fiber to be correctly cleaned and prepared. The first step is to strip all protective coatings from the ends of both fibers, then the fibers must be cleaned with a lint-free wipe and isopropyl alcohol, until they are squeaky clean. After that, the next step is to cleave the fiber, this is the action of cutting the end of the fiber so that the endface is completely flat, this requires a special tool called a cleaver. The fusion splicer should come with both strippers and a cleave tool.

Fiber Optic Fusion Splicing

Fiber Optic Fusion Splicing

Splicing

Both fibers are then placed into the fusion splicer, facing towards each other, where they become visible and magnified on-screen.
The fibers are then automatically precision aligned and then bought together through an electrical arc, where they are gently melted and permanently perfectly joined. The best quality Fusion Splicers align the inner core of the fiber, cheaper ones only align the external cladding.

Sealing

sealing
The now connected fibers are then placed inside a re-enforced protective sleeve (Heat Shrink Splice Protector), this keeps the fiber protected from bending and seals it against the elements. This Splice Protector is heat sealed onto the fiber using the oven on the splicer. Most fusion splicers incorporate an oven in the design.
The speed and relatively small size of fusion splicers have made them the most popular method of joining two fiber optic cables. Alternatives to fusion splicing include using optical fiber connectors or mechanical splices both of which have higher insertion losses, lower reliability and higher return losses than fusion splicing.