Views: 5 Author: Ada Ru Publish Time: 2022-08-29 Origin: Site
When light is transmitted in the optical fiber, loss will occur, and the optical fiber loss is mainly composed of the transmission loss of the optical fiber itself and the fusion loss at the optical fiber fusion splice.
Let us first understand the main factors that affect the loss of optical fiber fusion There are many factors that affect the loss of optical fiber fusion, which can be mainly divided into two categories: intrinsic factors and extrinsic factors of optical fibers. There are mainly four points: The fiber Poor concentricity between core and cladding According to ITU-T "Non-dispersion-shifted single-mode fiber", the structure and size parameters of G.652A fiber are: mode field diameter: 8.6±0.7~9.5±0.7μm cladding diameter: 125± 1μm concentricity error ≤ 0.8 μm, cladding out-of-roundness ≤ 2% Among the above parameters, the inconsistency of the fiber mode field diameter has the greatest impact. Within the standard range, after a fiber with a mode field diameter of 10μm and another fiber with a mode field diameter of 8μm are spliced under very good splice conditions, the theoretical calculation value of the splice loss at the splice can reach 0.18dB. Continuation is higher. During the construction of the optical cable laying, the construction shall be carried out in strict accordance with the construction requirements and process specifications proposed by the design unit and the optical cable manufacturer. When manually paying off the cable, the number of people pulling the optical cable shall not exceed 5; when mechanically paying off. a tension pay-off machine must be used. superior. Only in strict accordance with the construction requirements of the optical cable to prevent the optical fiber from being damaged during the construction of the optical cable, can the damage of the fiber core lead to the increase of the splice loss. In order to avoid the force and distortion of the optical fiber during the pulling process, the pulling end of the optical cable should be made when necessary. The bending radius of the optical cable during construction should be greater than 20 times the diameter of the optical cable, and the optical cable should be released from the cable shaft. The splicing work of the optical fiber should be completed by the well-trained splicing construction personnel. The splicing loss of the optical fiber joint should be measured in strict accordance with the splicing process, and the splicing loss does not meet the requirements. must be re-welded. Both ends of the optical cable entering the splice box must be firmly fixed, so as to prevent the position of the optical fiber connector from being shifted due to the twisting of the optical cable when the splice box is fixed, resulting in a large loss measurement value at the connector. During the splicing construction, it is often found that the splicing loss value measured under the 1550nm window meets the requirements, but the loss value at the re-measured joint after the splicing box is sealed is too large, which is usually caused by the positional displacement of the optical fiber joint. It can be re-measured at the 1310nm window. If the measured value is too small, the position of the fiber optic connector is misaligned, and the excess length of the fiber needs to be re-coiled; if it is too large, it is a fusion splicing problem and should be re-fused.
To avoid this phenomenon, use self-adhesive tape to fix the fiber connector and fiber excess length on the excess fiber tray. The coiling diameter of the excess length of the optical cable on both sides of the splice box should be more than 50cm, and should not be too small to avoid damage to the optical fiber due to excessive twisting. 4. The correct use of the fusion splicer has a great influence on the optical fiber fusion splicing loss, and the correct use of the fusion splicer is also a measure to reduce the optical fiber splice loss. The splicing of optical fibers should be carried out in a clean environment, such as in an engineering vehicle or a small tent, and it is not suitable for splicing in a dusty and humid environment.The prepared optical fiber section must be clean, and should not be exposed to the air for a long time, and should not be exposed to moisture. When splicing, it is necessary to correctly and reasonably choose and set the parameters of the fusion splicer according to the fiber type, such as pre-melting current, pre-melting time, main fusion current, main fusion time, etc. A discharge test should also be carried out before the optical cable is formally spliced. After the fusion splicer is used, the dust on the machine casing should be removed, and if it is used in a humid environment, it should also be treated with moisture-proof treatment. The service life of the electrode of the fusion splicer is generally 1000 times. It is required to run the cleaning program to clean the electrode after every 20 times of arc welding. However, when the fiber is clean and the splicing conditions are good, it can be spliced for about 60 times and then 1 discharge cleaning.
The working conditions When it is poor, it can be welded 30 to 40 times and then cleaned by discharge once, which not only prolongs the service life of the electrode but also does not increase the welding loss. The electrode of the welding machine that has been used for a long time will have a layer of dirt on the electrode, which will cause the discharge current to be too large and the welding loss value to increase. At this time, the electrode can be removed, wiped lightly with alcohol cotton, and then installed on the welding machine and discharged for cleaning. , if the discharge current is still too large after multiple cleanings, the electrode should be replaced.