Problems that should be paid attention to in the process of optical fiber fusion

With the popularization and application of optical fiber in the transmission of radio and television signals, the scale of the national cable radio and television optical cable transmission network has become larger and larger, providing a very superior transmission path and platform for analog TV, digital TV, information communication, etc., enabling the service audience. also expanding. It is particularly important to do a good job in maintaining the optical fiber network to ensure the uninterrupted and safe transmission of information.

However, due to weather, erection, migration and other reasons, cable breakage and fiber breakage accidents occur from time to time, and fiber splicing maintenance must be carried out in time. Therefore, it is very necessary to have a good set of optical fiber fusion splicing equipment and a group of professional technicians who are proficient in optical fiber fusion splicing technology to do a good job in network operation.

Optical fiber splicing is highly technical and requires high requirements. It has both certain technical skills and certain technical rules. During operation, careful observation, careful consideration, step-by-step implementation, and standardized implementation are required, especially in the aspects of end face preparation, fusion splicing, and fiber coils. It is careful and meticulous, and it is done in one go, so that the optical fiber fusion is beautiful and reliable, and meets the requirements of technical standards.

Fiber splicing

1. Preparation before fiber splicing

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

2. Preparation of the end face

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: stripping, cleaning and cutting.

1. Stripping of optical fibers

Optical fiber stripping means stripping the optical fiber coating. When operating, it is necessary to follow the principles of the smooth, stable and fast fiber stripping method to master its skills. "Flat" requires that you be flat. The thumb and index finger of the left hand pinch the optical fiber to make it horizontal, and the exposed length is subject to 5cm. The remaining fiber is naturally bent between the ring finger and the little finger to increase the strength and prevent slipping. "Stable" requires that the fiber stripping forceps be held firmly, and shaking and shaking are not allowed. "Fast", it is required to strip the fiber quickly. The fiber stripper should be perpendicular to the fiber, and the upper direction should be inclined inward at a certain angle, and then lightly clamp the right hand of the fiber with the jaws, and then forcefully push it out along the axis of the fiber. The whole process should be done in one go, and the peeling should be as complete as possible at one time, without hesitation and stagnation.

2. Cleaning of bare fibers

To clean the bare fiber, first observe whether the coating layer of the stripped part of the fiber is completely stripped. 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 to dip an appropriate amount of alcohol, dipping it, and gradually wipe it off. When cleaning, tear the cotton into small fan-shaped pieces with a flat surface, dip a little alcohol, clamp the fiber to be stripped, and wipe the fiber along the axis of the fiber, without reciprocating motion. A piece of cotton should be replaced in time after 2 to 3 times of use, and different parts and layers of cotton should be used each time, which can improve the utilization rate of cotton and prevent the re-contamination of bare fibers.

3. Cutting of bare fiber

The cutting of bare fiber is the most critical link in the preparation of fiber end face. In this link, precise and excellent cutters are the foundation, and strict and scientific operating specifications are the guarantee. There are two types of cutters, manual and electric. The manual cutter is easy to operate and has reliable performance. With the improvement of the operator's level, the cutting efficiency and quality can be greatly improved. The electric cutter has high cutting quality and is suitable for operation in cold conditions in the wild, but the operation is more complicated and requires longer bare fibers. Therefore, when choosing a cutter, a skilled operator should use a manual cutter for rapid optical cable connection or emergency rescue at room temperature; an electric cutter should be used for beginners or when working in colder conditions in the wild.

After the cutter is selected, the operator should operate according to the cutting operation specification and master the essentials of action. First of all, clean the cutter and adjust the position of the cutter. The placement of the cutter should be stable. When cutting, the action should be natural and smooth, not hurried or slow, 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 penetrated before peeling, and it is strictly forbidden to penetrate after the end face is prepared.

During the connection, the "V"-shaped groove, pressure plate and blade edge of the cutter should be cleaned according to the environment. The cleaning, cutting and splicing 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. When moving, handle it with care to prevent it from rubbing against other objects.

Third, the fusion of optical fibers

The fusion splicing fiber should be equipped with fusion splicing equipment with suitable battery capacity and precision according to the requirements of the optical cable engineering, namely the fusion splicer. Since the fusion splicer is a high-tech and high-precision equipment with high price, the selected fusion splicer should have excellent performance, stable operation, high welding quality, and be equipped with dust-proof windproof cover, large-capacity battery, etc., suitable for various Optical cable engineering (some fusion splicers are small in size, easy to operate, equipped with a simple cutter, and the battery and the host are combined into one, which is easy to carry, especially suitable for small and medium-sized optical cable projects).

The operator should be familiar with the performance characteristics of the fusion splicer used, and be proficient in the operation knowledge and essentials. Before fusion splicing, according to the material and type of optical fiber, set key parameters such as the optimal pre-melting main fusion current and time and the amount of optical fiber feeding on the fusion splicer. During the welding process, the "V"-shaped groove, electrodes, objective lens, welding chamber, etc. of the welding machine should also be cleaned in time. Observe whether there are air bubbles, too thin, too thick, virtual melting, separation and other undesirable phenomena in the welding at any time. Pay attention to the tracking and monitoring of the OTDR test instrument. As a result, the reasons for the above-mentioned undesirable phenomena were analyzed in a timely manner, and corresponding improvement measures were taken.

If virtual fusion occurs many times, check whether the materials and models of the two optical fibers to be spliced ​​match, 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 appropriately increased. After ensuring that there is no problem with the quality of optical fiber fusion, heat shrink the loose tube to protect the optical cable at the fusion point, and store it properly in order.

Fourth, fiber finishing

Fiber optic coiling is both a technology and an art. The scientific method of fiber coiling can not only avoid fiber breakage caused by extrusion, but also make the fiber layout reasonable and the additional loss small, which can withstand the test of time and harsh environment, and is conducive to future inspection and maintenance.

When the fiber is coiled, it is generally carried out in units along the loose tube or the branching direction of the optical cable. After each fusion splicing and heat shrinking of one or several optical fibers in the loose tube, or the optical fibers in a branch direction optical fiber, the fiber is coiled once to avoid the loose fiber. The confusion of optical fibers between casings or between different branch cables makes them suitable for layout, easy to install, easy to dismantle, and easy to maintain. It is also possible to reserve the heat-shrinkable tube placement unit in the tray as a unit of coil 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, thereby avoiding the same problem caused by different placement positions. The bundles of fibers are uneven, difficult to coil and fix, and even sharp bends and small circles occur.

1. Coil the fiber in the order of the middle first and then the two sides, that is, place the heat-shrinked sleeves in the fixing groove one by one, and then deal with the remaining fibers on both sides, which is beneficial to protect the optical fiber joints and avoid the possible damage caused by the coiled fibers. This method is commonly used when the optical fiber reserved disk space is small and the optical fiber is not easy to be coiled and fixed.

2. Start coiling the fiber from one end, fix the heat shrinkable tube, and then deal with the remaining fiber on the other side. Advantages: The fixed position of the optical cable sheath can be flexibly selected according to the length of the remaining fiber on one side, which is convenient and fast, and can avoid the phenomenon of sharp bends and small circles.

3. According to the actual situation, a variety of graphic fiber coils are used. According to the length of the residual fiber and the size of the reserved space, it should be coiled naturally according to the situation. It must not be pulled hard. Various shapes such as circle, ellipse, and "~" shape should be used flexibly. Reserve space and effectively reduce additional losses caused by fiber coils.

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

Five, optical cable connection quality inspection

In the whole process of fusion splicing, the OTDR test instrument should be used to strengthen monitoring to ensure the quality of optical fiber fusion, reduce the additional loss caused by the coiled fiber and the possible damage to the optical fiber caused by the sealing box. It must not be judged by the naked eye. Bad:

(1) Real-time tracking and monitoring of each core fiber during the fusion process to check the quality of each fusion point;

(2) After each coiled fiber, conduct routine inspection on the coiled fiber to determine the additional loss caused by the coiled fiber;

(3) Before sealing the splicing box, uniformly measure all the optical fibers to find out whether there is any leakage and whether the reserved space of the optical fiber has squeezed the optical fiber and the connector;

(4) After the box is sealed, a final monitoring of all optical fibers is performed to check whether the box is damaged to the optical fiber.

In short, optical fiber splicing is a job with strong skills and high quality requirements. The operator must have a rigorous and meticulous work style, diligently summarize and think about the work spirit, and continuously improve operating skills in practice, accumulate technical experience, Only in this way can we comprehensively improve the quality of optical cable connection, complete the optical cable connection task with quality and quantity, do a good job in the maintenance and service of the information transmission platform, and achieve high-quality and uninterrupted transmission of information.