Fiber fusion splicing is mainly divided into four steps: stripping, cutting, melting, and protecting.
Stripping: refers to stripping the fiber core in the optical cable, which includes the outermost plastic layer, the middle steel wire, the inner plastic layer and the color paint layer on the surface of the optical fiber.
Cutting: refers to cutting the end face of the optical fiber that is stripped and ready to be spliced with a “cutter”.
Fusion: refers to the fusion of two optical fibers in a “fusion splicer”.
Protection: refers to the protection of the fusion-spliced optical fiber connector with a “heat shrinkable tubing”.
Fiber end face preparation
The preparation of the fiber end face includes stripping, cleaning and cutting. Qualified fiber end face is a necessary condition for fusion, and the quality of the end face directly affects the quality of fusion.
(1) Stripping of optical fiber coating
Good command of the flat, steady, and fast three-character stripping method. ” flat” means that the holding fiber level. Pinch the optical fiber with the thumb and forefinger of the left hand to make it horizontal, and the exposed length is 5cm. The remaining fiber is naturally bent between the ring finger and the little finger to increase strength and prevent slipping. “Stable” means that the stripping pliers should be held firmly. “Quick” means that the fiber must be stripped quickly. The stripping pliers should be perpendicular to the fiber ,tilt inward to a certain Angle in the upper direction. Then use the jaws to pinch the fiber, use your elbow to push it out, The whole process should be natural and smooth.
(2) Cleaning of bare fiber
Observe whether the coating of the stripped part of the optical fiber is completely stripped off. If there is any residue, it should be stripped again. If there is a very small amount of coating that is not easy to peel off, you can use a cotton ball dipped in a suitable amount of alcohol, while dipping it, and gradually wipe it off. A piece of cotton should be replaced in time after being used for 2 to 3 times, and different parts and layers of the cotton should be used each time, which can improve the utilization rate of cotton and prevent the two pollution of fiber probe.
(3) Cutting of bare fiber
Cutting is the most critical part in the preparation of optical fiber end faces. A precise and excellent cutter is the foundation, and strict and scientific operating specifications are the guarantee.
The choice of cutters has manual and electric two kinds. The former is simple to operate and reliable in performance. With the improvement of the operator’s level, the cutting efficiency and quality can be greatly improved, and the bare fiber is required to be shorter, but the cutter has higher requirements for the environmental temperature difference.
The latter has higher cutting quality and is suitable for operation under cold conditions in the field, but the operation is more complicated, the working speed is constant, and the bare fiber is required to be longer. Skilled operators should use manual cutters for fast fiber optic cable splicing or emergency rescue at room temperature; on the contrary, for beginners or when working in colder conditions in the field, use electric cutters.
Fiber Fusion splicing
Fiber fusion splicing is the central link of splicing work, so high-performance fusion splicers and scientific operations in the splicing process are very necessary.
(1) Selection of fusion splicer
The selection of the fusion splicer should be equipped with fusion splicing equipment with appropriate battery capacity and precision according to the requirements of the optical cable project.
(2) Parameter setting of fusion splicer
Before fusion splicing, according to the material and type of the optical fiber, set the key parameters such as the optimal pre-melting main melting current and time, and the amount of fiber input. During the fusion process, the V-shape groove, electrode, objective lens, welding chamber, etc. of the fusion machine should be cleaned in time, and the fusion should be observed at any time whether there are bubbles, too thin, too thick, false melting, separation, etc., and pay attention to the OTDR tracking monitoring results.
Analyze the causes of the above-mentioned undesirable phenomena in time, and take corresponding improvement measures. If false fusion occurs repeatedly, check whether the materials and models of the two optical fibers to be fused are matched, whether the cutter and the fusion splicer are contaminated by dust, and check the oxidation status of the electrodes. If there is no problem, the fusion current should be appropriately increased.
Ensuring the quality of fiber optic cable connection
It is of great significance to strengthen OTDR monitoring to ensure the quality of fiber fusion and reduce the additional loss caused by the coil fiber and the damage caused by box sealing to fiber.In the whole connection work, the four OTDR monitoring procedures must be strictly implemented:
(1) Real-time tracking and monitoring of each core fiber during the fusion splicing process to check the quality of each splicing point;
(2) After each coiling fibers, conduct routine inspection on the coiled fiber to determine the additional loss caused by the coil fiber;
(3) Before sealing the splice box, perform a unified test on all optical fibers to find out whether there is any missing test and whether the optical fibers and connectors are squeezed between the optical fiber reserve trays;
(4) After sealing the box, perform a final inspection on all the optical fibers to check whether the sealing box damages the optical fibers.
Optical cable continuous is a meticulous work, especially in the end-face preparation, fusion, coiling and other links, requiring careful observation, careful consideration, and operating specifications. In short, in the work, we must diligent in summing up and thinking, in order to improve practical operation skills, reduce splicing loss, and comprehensively improve the quality of optical cable splicing