Fiber Fusion Problems

1. Preparation before fiber splicing

Before optical fiber fusion splicing, you must first prepare the necessary operating equipment, tools and necessary materials such as fiber strippers, cutters, fusion splicers, heat shrinkable sleeves, alcohol cotton, etc., and check whether the power supply of the fusion splicer is sufficient and whether the various materials are complete, etc. , and then remove the outer sheath of the optical fiber to be fused, the length of the steel wire, etc., and find out the corresponding optical fiber that needs to be fused. The four steps of quality inspection are carried out one by one.

Second, the preparation of the end surface

A qualified fiber end face is a necessary condition for fusion splicing, and the quality of the end face will directly affect the quality of fusion splicing. The preparation of the fiber end face includes three steps of stripping, cleaning and cutting.

1. Stripping of optical fiber

Optical fiber stripping refers to stripping the coating layer of optical fiber. During operation, the principle of flat, stable and fast three-character fiber stripping method should be followed, and the skills should be mastered. "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. "Stable" requires that the fiber stripping pliers should be held firmly, and trembling and shaking are not allowed. "Fast" means that the fiber should be stripped quickly. The fiber stripping pliers should be perpendicular to the fiber and tilted inward at a certain angle. Then use the jaws to gently hold the right hand of the fiber, and then forcefully push it out along the fiber axis. The whole process should be completed in one go, try to peel and cover thoroughly at one time, without hesitation or stagnation.

2. Cleaning of bare fiber

To clean the bare fiber, first observe whether the coating layer of the stripped part of the fiber is completely stripped off, and 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. When cleaning, tear the cotton into flat fan-shaped pieces, dip a little alcohol, clamp the stripped optical fiber, and wipe along the optical fiber axis without reciprocating motion. A piece of cotton should be replaced in time after being used for 2 to 3 times, and different parts and layers of cotton should be used each time, so as to improve the utilization rate of cotton and prevent re-pollution of bare fibers.

3. Cutting of bare fiber

The cutting of bare fiber is the most critical link in the preparation of optical fiber end face. In this link, precise and excellent cutting knives are the foundation, and strict and scientific operating specifications are the guarantee. There are two kinds of cutters, manual and electric. The manual cutter 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. The cutting quality of the electric cutter is high, and it is suitable for working in the field under cold conditions, but the operation is more complicated, and the bare fiber is required to be longer. Therefore, when choosing a cutter, a skilled operator should use a manual cutter for quick cable connection or rescue at room temperature; for beginners or when working in colder conditions in the field, an electric cutter should be used. After the cutter is selected, the operator should operate according to the cutting operation specifications and master the essentials of the action. 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 steady, not in a hurry, so as to avoid the occurrence of bad end faces such as broken fibers, bevels, burrs and cracks, and ensure cutting the quality of. At the same time, beware of end-face contamination. The heat-shrinkable sleeve should be inserted before stripping, and it is strictly forbidden to insert after the end surface is prepared. During the connection, the "V" groove, pressure plate and blade of the cutter should be cleaned according to the environment. The time of cleaning, cutting and welding of bare fibers should be closely linked, and the interval should not be too long, especially the prepared end faces, and should not be placed in the air. Handle with care when moving to prevent rubbing against other objects.

3. Fiber splicing

Fusion optical fiber should be equipped with fusion splicing equipment with suitable battery capacity and precision according to the requirements of optical cable engineering, that is, fusion splicing machine. Since the fusion splicer is a high-tech, high-precision equipment, and the price is high, the selected fusion splicer must have excellent performance, stable operation, high welding quality, and is equipped with a dustproof windshield and a large-capacity battery. Optical cable engineering (some fusion splicers are small in size, easy to operate, equipped with a simple cutter, the battery and the host are combined into one, easy to carry, especially suitable for small and medium-sized optical cable projects). Operators should be familiar with the performance characteristics of the fusion splicer used, master the operating knowledge and essentials, and should not be half-knowledgeable. 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 optical fiber feeding on the fusion splicer. During the welding process, the "V" groove, electrode, objective lens, welding room, etc. of the welding machine should be cleaned in time, and there are no bubbles, too thin, too thick, virtual melting, separation and other bad phenomena in the welding at any time, and pay attention to the tracking and monitoring of the OTDR test instrument As a result, timely analyze the causes of the above undesirable phenomena and take corresponding improvement measures. If virtual fusion occurs many times, check whether the materials and models of the two optical fibers to be fused are matched, whether the cutter and the fusion splicer are polluted by dust, and check the oxidation status of the electrodes. If there is no problem, the fusion current should be increased appropriately. After ensuring that there is no problem with the quality of the optical fiber fusion splicing, loosen the sleeve by heat shrinkage to protect the optical cables at the fusion splicing point, and place them in order and store them properly. After cleaning the site a little, perform fiber reeling.

4. Disk fiber finishing

Optical fiber coiling is both a technology and an art. The scientific fiber coiling method can not only avoid fiber breakage caused by extrusion, but also make the fiber layout reasonable, with low additional loss, which can withstand the test of time and harsh environment, and is beneficial to future inspection and maintenance. When coiling fibers, it is generally carried out in units along the branching direction of the loose tube or optical cable. After each fusion splicing and heat shrinking of one or several optical fibers in the loose tube or optical fibers in a branch direction optical cable, the fiber is coiled once to avoid loosening of the optical fiber. The disorder of the optical fibers between the bushings or between different branch optical cables makes the layout proper, easy to reel, easy to dismantle, and easy to maintain. It is also possible to reserve the placement unit of the heat-shrinkable tube in the tray as a unit of fiber, according to the number of heat-shrinkable tubes that can be placed in a small placement area in the reserved tray in the splice box, so as to avoid the same situation caused by different placement positions. The bundle of optical fibers is uneven, it is difficult to coil and fix the fibers, and even sharp bends and small circles appear.

1. Coil the fibers first in the middle and then on both sides, that is, place the heat-shrinkable sleeves in the fixing groove one by one, and then deal with the remaining fibers on both sides, which is conducive to protecting the fiber joints and avoiding possible damage caused by the fiber coiling. This method is often used when the optical fiber reserved disk space is small and the optical fiber is not easy to coil and fix.

2. Coil the fiber from one end, fix the heat-shrinkable tube, and then process the remaining fiber on the other side. Advantages: According to the length of the remaining fiber on one side, the cable sheath tube can be flexibly selected to be placed in a fixed position, which is convenient and fast, and can avoid sharp bends and small circles.

3. According to the actual situation, a variety of graphic disk fibers are used. According to the length of the remaining fiber and the size of the reserved space, it will be coiled naturally according to the trend, and it must not be pulled hard. It should be flexibly used in various graphics such as circle, ellipse, "~" shape (note that R≥4cm), and maximize the use as much as possible. Reserve space and effectively reduce the additional loss caused by the fiber coil.

4.Handling of other special cases, such as individual optical fibers that are too long or too short, can be placed at the end and coiled separately; when there are special optical devices, they can be processed in another coil, if they are coiled together with ordinary optical fibers , it should be lightly placed on the ordinary optical fiber, and a buffer liner should be added between the two to prevent the fiber from being broken due to extrusion, and the tail fiber of the special optical device should not be too long.