Optical fibre Fusion Splicing: Factors that are

possible affecting the Signal Quality

Fibre optic cables are joined together using slicing mechanism. It is a permanent solution as the two ends of the fibre optic cables are joined using heat. Much like welding, the physical property of the two participating fibre optic cables should be more or less similar. Differences in the diameter, outer jacket quality and age of the fibre optic cables also play significant role in defining the extent to splicing required.

The methods of joining two Fibre optic cables:-

Fibre optic cables can be physically joined using two methods:o    Splicingo    Connector attachment

Splicing of fibre optic cables is done using two mechanisms:o    Mechanical splicingo    Fusion splicing

Optical fibre cables are usually joined for permanent purposes using fusion splicer machines. Optical connectors on the other hand are used at places where the fibre optic cables are engaged and disengaged for operational assessment and maintenance reasons. For industrial purposes, the optical fibre connectors are preferred as it allows the expansion of the layout.

Operations carried out in the Fusion splicing methods:-

Fusion splicer machines perform the connection of two optic fibre cables using:o    Core alignment o    V-Groove alignment, also called Cladding alignment o    Reinforced splicingo    Fibre cleaving

Factors that affect Splicing of Fibre Optic cables:-

The major factor that affects the quality of splicing is the alignment of the fibre optic cables. The opposing cores must be properly aligned together in order to have highest quality. This is achieved using a fusion splicer machine. In order to pick the best fusion splicer for joining, you must know the types of losses prevalent in the cables joined externally.

–    Poor Alignment

The best quality splicing using fusion splicer machines ensure that the optical fibre cables are impeccable aligned. The splice loss is reduced to less than 12 per cent in cases where the fusion splicer managed to attach the cables’ concentricity with minimum lip gap.

–    Choice of cables

Fusion splicer can’t be used to align different types of cores. For example, a single-mode optic fibre cable can be spliced with another single-mode cable. You should not use the fusion splicing in cases where misalignment is greater than one micrometer. A misalignment of one micrometre causes approximately 0.2 Decibels of signal loss.

–    Minimize end gap

Despite best quality fusion splicing, two fibre optic cables can still end up having small gaps. This is called ‘Tail gap’. The presence of tail gap leads to a single loss of 0.6 decibels and magnifies depending on the refractive index of the material used in the fibre optic cable. To ensure error-free signal transmission, ensure that the surface of the fibre optic cables is properly cleaned and the refractive index at the spot of fusion splicing is consistent as the rest of the cable.

Note:

Use of fibre optic connectors is preferred in cases where the tail gap can’t be reduced. Connectors minimize the tail gap and consequently the signal loss.

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