General Notes on Fusion Splicing of Optical Fibers

Optical fibers are joined by arc fusion splicing. Fusion splicing procedures include fitting a splice protection sleeve, removal of coating layers to expose glass fiber, fiber cleaning, arc fusion splicing, and reinforcing the splice by heating the splice protection sleeves.

General Notes on Fusion Splicing of Optical Fibers 1

Fitting of fiber protection sleeve: Splice protection sleeves are used to protect the glass portion of the optical fibers exposed at the location of the splice. These generally heat shrinkable sleeves. Splice protection sleeves shall be inserted through one of the optical fibers prior to coating removal at the fiber end in order to splice it with other fibers. Technical persons should not forget to ensure that the sleeve is passed through the fiber.

Removal of Fiber Coating layers: Using a fiber stripper, fiber coating layers shall be removed to expose the glass fibers. After the removal of coating material, the fiber stripper shall be cleaned in order to make it free from dust of coating material. There are special coating removal tools available for ribbon coating removal. These heated ribbon coating removal tools are heated for 5 seconds before the removal process.

Fiber Cleaning: After removing the coatings from the fibers, clean the fiberglass with alcohol. Debris of coating layers present on the fiberglass will lead to poor concentricity in fusion splicing or they will result in increased splice loss. Clean the fiberglass thoroughly after coating removal helps to reduce the splice loss and improved healthy splicing of optical fibers. In the case of Ribbon fiber splicing, the fiber ends may stick together while cleaning with alcohol.  This will cause misalignment of fibers and result in high splice loss. To avoid this, the ribbon fiber ends are spread using a small brush.

Fiber Cleaving: The loss characteristics of a fusion splice depends on the cleaving. To reduce cleaving defects, fiber holders and the blade of the cleaver shall be cleaned thoroughly and on a regular basis. Fiber cleavers are available for single fiber cleaving and multi fiber cleaving. Cleaved fiber ends shall be kept away from other objects including our own fingers to avoid damage to the cleaved fiber ends.

Fusion Splicing: Fusion splicing shall be done as per the instruction manual provided by the fusion splicing machine manufacturer. Dirt in the V-grooves or clamp of a fusion splicing machine will result in high splice loss due to poor concentricity. Cleanliness of splicing machine is important. It is possible to detect faulty conditions of cleaved ends if pre-splicing inspection with a dual-axis observation facility is available with the splicing machine. If the fiber has more curl, slightly squeeze the fiber with fingers to remove the curl. The placed fiber should be bent downward.

Spliced fiber Reinforcement: Spliced optical fibers shall be covered with the protection sleeve. Position the protection sleeve so that its midpoint is close to the center of the splice. Place the spliced portion along with the protection sleeve over it in the heater unit. The heater will allow the protection sleeve to shrink over the fiber at the splice location. Generally, a steel rod is present inside the splice protection sleeve as a reinforcement element to give strength to the splice point. Avoid bending or twisting the fiber while moving.

Fusion splicing requires a good level of skill and is considered an important task in the deployment of fiber optic cable. The cost of a splice varies from region to region. The general trend in Europe is around US$ 25 for one splice, whereas in MEA the rate is supposed to be around US$ 20.

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