Fiber splicing is mainly divided into four steps: stripping, cutting, melting, and protecting:
Stripping: refers to the stripping of the optical fiber core in the optical cable, which includes the outer plastic layer, the middle steel wire, the inner plastic layer and the color paint layer on the surface of the optical fiber.
Cutting: It refers to cutting the end face of the optical fiber that has been stripped and ready to be fused with a "cutter".
Fusion: refers to the fusion of two optical fibers together in a "fusion splicer".
Protection: It refers to protecting the spliced optical fiber connector with a "heat shrinkable tube":
1. Preparation of the end face
The preparation of the fiber end face includes stripping, cleaning and cutting. A qualified fiber end face is a necessary condition for fusion splicing, and the quality of the end face directly affects the quality of fusion splicing.
(1) Stripping of optical fiber coating
Familiar with the flat, stable, fast three-character fiber stripping method. "Ping" means keeping the fiber flat. Pinch the optical fiber with the thumb and index finger of the left hand to make it horizontal. 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.
(2) Cleaning of bare fibers
Observe whether the coating layer 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 layer that is not easy to peel off, use a cotton ball dipped in an appropriate amount of alcohol, and wipe it off gradually while dipping. A piece of cotton should be replaced in time after being used 2-3 times, and different parts and layers of cotton should be used each time.
(3) Cutting of bare fiber
Choice of Cutter There are two kinds of cutters, manual and electric. The former is easy 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 on the ambient temperature difference. The latter has higher cutting quality and is suitable for working 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. It is advisable for skilled operators to use manual cutters for fast optical cable splicing or emergency rescue at room temperature; on the contrary, beginners or when working in colder conditions in the field, use electric cutters directly.
First of all, clean the cutter and adjust the position of the cutter. The cutter should be placed stably. When cutting, the movement should be natural and stable. Don’t be heavy or anxious to avoid broken fibers, bevels, burrs, cracks and other bad end faces. In addition, rationally allocate and use one's own right fingers to make them correspond to and coordinate with the specific parts of the cutter, so as to improve cutting speed and quality.
Beware of contamination on the end surface. The heat shrinkable sleeve should be inserted before stripping, and it is strictly forbidden to penetrate after the end surface is prepared. The time of cleaning, cutting and welding of bare fibers should be closely connected, and the interval should not be too long, especially the prepared end faces should not be placed in the air. Handle with care when moving to prevent rubbing against other objects. During the splicing, the "V" groove, pressure plate and blade of the cutter should be cleaned according to the environment to prevent contamination of the end surface.
2. Fiber splicing
(1) Selection of welding machine
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 welding machine
Splicing procedure According to the material and type of optical fiber before splicing, set the key parameters such as pre-melting main melting current and time, and the amount of fiber feeding.
During the welding process, the "V" groove, electrode, objective lens, welding chamber, etc. of the welding machine should be cleaned in time, and any bad phenomena such as bubbles, too thin, too thick, virtual melting, separation, etc. should be observed during the welding at any time, and attention should be paid to the tracking and monitoring results of OTDR. Analyze the causes of the above adverse phenomena in a timely manner and take corresponding improvement measures.
3, disc fiber
The scientific fiber coiling method can make the optical fiber layout reasonable, the additional loss is small, can withstand the test of time and harsh environment, and can avoid the phenomenon of fiber breakage caused by extrusion.
(1) Disk fiber rules
The fiber is coiled in units along the loose tube or the branching direction of the optical cable. The former is applicable to all splicing projects; the latter is only applicable to the end of the main optical cable, and has one input and multiple outputs. Most of the branches are small logarithmic optical cables. The rule is to reel the fiber once after splicing and heat-shrinking one or several fibers in loose tubes, or fibers in a split direction cable. Advantages: It avoids the confusion of optical fibers between loose tubes of optical fibers or between different branch optical cables, making it reasonable in layout, easy to reel and dismantle, and easier to maintain in the future.
(2) The method of disk fiber
First the middle and then both sides, that is, first place the heat-shrinkable sleeves in the fixing groove one by one, and then process the remaining fibers on both sides. Advantages: It is beneficial to protect the fiber joints and avoid possible damage caused by the fiber coil. This method is often used when the space reserved for the optical fiber is small and the optical fiber is not easy to coil and fix.