Optical cable is composed of cable core, reinforced steel wire, filler and sheath. In addition, there are waterproof layer, buffer layer, insulated metal wire and other components as needed. 1. Filler grease: It is a substance present in loose tubes, mainly containing fiber paste and cable paste. To prevent water and moisture from penetrating the fiber optic cable. Because optical fibers are extremely sensitive to HO- generated by water and moisture; water and moisture will expand cracks on the surface of the optical fiber, causing a significant decrease in the strength of the optical fiber. The hydrogen produced by the chemical reaction between moisture and metal materials will cause the optical fiber to absorb hydrogen. loss, resulting in an increase in the transmission loss of the optical fiber, seriously affecting the quality and service life of the optical cable. National standards require water-blocking performance: three meters of optical cable, one meter of water column pressure, and no water seepage for 24 hours. Under normal circumstances, the fiber paste should fill the entire loose tube, and the cable paste should fill every gap in the optical cable core under pressure. 2. Outer sheath: Indoor optical cables generally use polyvinyl chloride or flame-retardant polyvinyl chloride. The appearance should be smooth, bright, flexible, and easy to peel off. The outer sheath of poor-quality optical cables has poor smoothness and is prone to sticking to the tight sleeves and aramid fibers inside. The main function of the outer sheath of optical cables is to cope with different complex climatic environments and ensure the stable use of optical cables for at least 25 years. The optical cable sheath must not only have a certain strength, low thermal deformation, abrasion, water permeability, thermal shrinkage and friction coefficient, but also have strong resistance to environmental stress and good material processing performance. 3. Protective materials steel strip and aluminum strip. The steel strips and aluminum strips in optical cables are mainly used to protect optical fibers from mechanical side pressure and moisture resistance. Chrome-plated steel strips are generally used in better optical cables. Optical cables with unqualified quality will suffer from internal corrosion over time, resulting in poor moisture resistance; the tin-plated layer has poor heat resistance, with a melting point of only 232 degrees Celsius. In application, due to the high temperature during sheath extrusion, the peeling strength is insufficient. Deterministic, affecting the moisture resistance of optical cables. The melting point of chromium reaches 1900 degrees Celsius, and its chemical properties are very stable. It will not rust when placed in the air or immersed in water at room temperature. It has very good corrosion resistance. Because the surface is easily oxidized to form a passivation layer, it has good environmental resistance. For aluminum strips, unqualified heat-coated aluminum strips are generally used instead of qualified cast-coated aluminum strips, which will also affect the performance of optical cables. 4. Compression-resistant material steel wire: The steel wire of outdoor optical cables from regular manufacturers has been phosphated and has a gray surface. Such steel wires will not increase hydrogen loss after being cabled, will not rust, and have high strength. Inferior optical cables are generally replaced with thin iron wires or aluminum wires. The identification method is easy - they appear white and can be bent at will when held in the hand. Optical cables produced with such steel wires have large hydrogen losses. Over time, the two ends where the fiber optic boxes are hung will rust and break. 5. Loose tube: The loose tube used to install the optical fiber in the optical cable should be made of PBT material. Such a tube has high strength, does not deform, and is resistant to aging. Inferior optical cables generally use PVC as casings. The outer diameter of such casings is very thin and will flatten when pinched by hand. It is a bit like the straws we use to drink drinks. With the development of science and technology in our country, optical fiber and cable technology has become more and more mature, promoting the construction of triple network integration, Internet of Things, mobile Internet, broadband communications, and wireless WLAN. For optical fiber, it is the key to network transmission.A medium, compared with other media, has a large transmission capacity, is not subject to electromagnetic interference, has very good confidentiality, and has a long relay distance, which saves a lot of copper material usage and reduces processing costs. Therefore, it can be widely promoted and used.