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 fibres together using an electrical arc. The arc is precisely applied to join the two fibres together in such a way that light passing through the fibres are not scattered or reflected back by the splice.
Splicing of fibre optic cable requires added protection of the splice. This is achieved by using a heat shrink which allows the splice and region surrounding it to be as strong as or stronger than the original fibre.
Fiber Splicing is usually a three-stage process; we will now have a look at each of these optical fibre splicing stages.
Stage 1 – Preparation
The first stage is the preparation stage.
The process of fusion splicing requires two pieces of bare fibre to be correctly cleaned and prepared.
With fibre optic splicing comes some cable preparation. Part of this procedure is to remove the many layers of jacketing protecting the fibres to expose each individual fibre strand. Once we have completed this we can strip the ends of both fibres being spliced.
The next step is to clean the fibres with a lint-free wipe and some isopropyl alcohol, until they are squeaky clean.
Only then can we cleave the fibre. This is the action of cutting the end of the fibre so that the end face is completely flat.
This requires a special tool called a cleaver. The fibre optic splicing machine normally includes a cleave tool for this purpose.
Stage 2 – Fusion Splicing
Both fibres are then placed into the alignment fusion splicer, facing towards each other, where they become visible and magnified on-screen. The splicing of fibre optic cable can then be automatically controlled by the fiber optic cable splicer. The fibres are precision aligned and moved together where they are gently melted by an electric arc and permanently joined to perfection.
The best quality Fusion Splicers provide core alignment of the fibre, cheaper ones only align to the external cladding.
Stage 3 – Sealing and protecting
The now connected fibres are then placed inside a re-enforced protection sleeve (Heat Shrink Splice Protector). This keeps the fibre protected from bending and seals it against the elements.
This Splice Protector is heat shrunk onto the fibre using the oven provided on the splicer. Most fusion splicers incorporate an oven in the design.
In summary, Fusion Splicers are a very convenient way to join two fibres together. Their relatively small size, speed and reliability have made them a popular splicing cable fiber optic tool.
Alternatives to fusion splicing include using optical fibre connectors or mechanical splices.
Both of which have higher insertion losses, lower reliability and higher return losses than fusion splicing.