Fiber splicing is also called fiber optic cable splicing, that is using a special equipment optical fiber fusion splicer to fuse two bare fibers that are not connected into a whole. Fiber splicing is not as simple as fusing two bare fibers together, it’s a process: stripping fiber cable jacket and tubes, securing the fiber, cleaving the fiber, stripping the coating, fusion splicing the fiber, placing splice into splice tray and so on, and is a series of meticulous work. Especially in the end face preparation, fusion splicing, placing splice and other aspects, the operator is required to observe carefully, think over, and standardize the operation.
Tool: Fusion splicer, 95% industrial alcohol, fiber optic stripper, fiber cleaver, absorbent cotton or dust-free paper, needle-nose pliers, wire stripper, connectors, light source, optical power meter, cutter, vice and so on.
Environment: Dust-free environment is the best, or where dust is not visible.
Advantages of fiber splicing:
1)Small loss (0.01~0.02)
2)Basically not affected by the environment, low maintenance cost
Disadvantages of fiber splicing:
1)Expensive splicing cost (fusion splicer is expensive)
2)Fusion splicer is inconvenient to operate due to the limitation of its own battery and environment (strong wind, cold weather, etc.)
Following is the steps of fiber splicing, taking Optical Fiber Splice Closure as example (Optical Fiber Terminal Box, ODF Distribution Frame or other equipments are similar)
1.Strip the outer armor protection layer of the optical cable and secure
Cut the fiber optic cable (Cutter) at a distance of 0.6 to 0.8 meters from one end, use the cutter to remove fillers (the layer attached to the outer sheath of the optical cable), cut the wire with a vise and leave a few centimeters of wire to secure the cable. Wipe off the grease outside the loose tube. Open the splice closure, loosen the screws, wrap the optical cable with tape, and secure the optical cable in a suitable position.
2. Peel off the loose tube and clean it with paper
At a suitable position, use a cutter lightly cut loose tube or use a wire stripper to make a small opening, gently fold, the loose tube breaks, remove the loose tube by hand. Use papers to wipe off the oil on the surface of the optical fiber after the loose tube is removed and clean it up.
3. Use wire stripper to peel off the fiber coating
Put the optical fiber into the heat shrinkable tube, use wire stripper to peel off the coating at the 3CM of the optical fiber, and wipe off the coating residue with alcohol absorbent cotton.
4. Use fiber cleaver to make the end face
Place the cleaned bare fiber at the marked position on the fiber cleaver, and after securing it, cut it to make the fiber end face. The cut bare fiber has a flat end surface, and the end surface is perpendicular to the central axis of the bare fiber, without defects and burrs. The length of the bare fiber made on the end surface should be 1~2 CM.
5. Fusion splice
Open the dust cover of the optical fiber fusion splicer, put the fiber into the V-row groove (be careful not to let the end face touch anything, so as not to contaminate it), close the dust cover, and observe the end face condition on the monitor (if the end face is not ideal, replace it, or reset), press the SET button on the fusion splicer. Note: Fiber splicing should be carried out in a clean environment, the cleaver should be kept clean, and the fiber end face should not be exposed to the air for too long after cutting, it’s to avoid contamination.
6. Evaluation of fiber fusion quality
Observe the connection part on the monitor. The following situations should be reconnected: connection marks, spherical connections, joints thicken, axial offset, air bubbles, thinning of the joints and other situations. Connection loss estimation: check the monitor of the fusion splicer to see whether the loss value is qualified, generally less than or equal to 0.02dB, tension test: 240g, if there is no tension test, bend lightly by hand if necessary.
7. Reinforce bare fiber
After the fiber is fused, there will be a bare fiber with a length of 2~4cm. There is no coating layer, the strength is greatly reduced, and the fusion part becomes more brittle after being burned by the arc, so it needs to be reinforced at the bare wire. Open the dust cover, lift up the large pressure plate, and gently take out the spliced optical fiber from the splicer. Gently pull the heat shrinkable tube to the joint, open the heater cover, and put the optical fiber connector covered with the heat shrinkable tube into the fusion splicer heater, close the cover and the fusion splicer will automatically heat up. After heating, it can be taken out after cooling.
8. Placing splice into splice tray
Placing splice needs to be careful and it’s also an art. There are generally two ways: 1. Start from middle then the two sides, that is, the heat shrinkable tube is placed in the fixing groove first, and then placing the remaining fibers on both sides. 2. Start from one end, secure the heat shrinkable tube, and then place the remaining fiber on the other side. Note: If several fibers are too long or too short, they can be placed separately at the end, naturally placed according to the length of the remaining fiber and the reserved length; don’t pull it hard, you should use round, elliptical, C-shape, S and other fiber placing methods flexibly; If the fiber radius is more than or equal to 4cm, it is necessary to use the space of the splice tray as much as possible to effectively reduce the additional attenuation caused by placing.
After the splice closure (or terminal box) is placed with fiber, make a seal to prevent water or other small animals from entering and damaging the fiber.
After the fiber fusion splicing is completed, it needs to be tested, usually it’s using a VFL to test the light core-by-core, and observe the light intensity of the other end to judge the quality of fiber splicing; sometimes it is tested with an optical power meter or plugged into the optical communication equipment (As long as there is a signal, the splicing is completed); some projects with strict requirements need to provide test reports with OTDR.
While testing, it is necessary to mark the corresponding point of each core fiber, and file the fiber link situation in order to install and debug fiber optic equipment and later maintenance.