The first category is the optical attenuation caused by the too small bending radius of the optical cable.Because the fiber is sensitive to stress, bending the fiber has the potential to cause light signals to escape through the fiber cladding, and as the bend becomes sharper, the light signal will leak more. Fiber bending will cause fiber attenuation. As the bend radius decreases, the amount of attenuation from fiber bending increases.The fiber bend radius is not the same for all cables or patch cords and may vary depending on the type of cable or how it is manufactured. At present, the commonly used single-mode optical fiber core model is G652. Generally, the minimum bending radius of the optical fiber cable made of this type of optical fiber depends on the diameter and type of the optical cable. In order to be relatively safe, take the maximum value. For the commonly used G652 optical fiber, the minimum bending radius is selected to be greater than or equal to 30mm. Due to problems such as the armored structure of the optical cable, the bending radius is too small to easily cause damage to the armored sheath. The bending radius of the optical cable should generally not be less than ten times the outer diameter (OD) of the optical cable. Under the tensile load, the bending radius of the optical cable is 15 times the outer diameter. Assuming that the outer shell diameter of a certain optical cable is 1cm, the bending radius should be between 10cm and 15cm. To be on the safe side, common optical cable reels are usually best with a diameter of 30cm.When the optical cable is laid, due to irregular construction, the semi-bending radius of the optical cable is less than 30mm, and it is very easy to cause optical attenuation. In this case, as long as the bending radius fault point is found and the bending radius of the optical cable is restored to greater than 30mm, this fault can basically be solved.The second type is the light decay caused by the water entering the connector box.There is a splice box every 2km-3km of the optical cable, and the optical fiber will be fused once in the splice box. If the optical cable is damaged due to some reasons, 1-2 splice boxes will be added at the damaged position. Optical cable splice boxes are generally made of hard engineering plastics. The optical cable splice box is divided into upper and lower halves. There is a sealing strip between the upper cover and the lower cover of the splice box to prevent moisture intrusion. Due to the material problem of the splice box and the poor sealing of the sealing strip of the splice box or material problems, groundwater invades the inside of the splice box, resulting in optical fiber fusion. Spot soaked in water.The composition of the optical fiber is mainly SiO4, and the composition form is that silicon-oxygen tetrahedrons are connected to each other, and oxygen atoms exist in the form of bridging oxygen. If water (H2O) is encountered, the surface of the optical fiber will gradually undergo a hydrolysis reaction after adsorption, so the silicon-oxygen bond will be broken, which will cause the optical fiber to break. This really explains why optical fiber is afraid of water from the source!In fact, the waterproof measures of the optical fiber cable are relatively perfect under normal circumstances, but once water enters the optical fiber fusion joint, the sealing area of the splice box, and the exposed area of the bare wire, the life of the optical fiber will be reduced sharply or even the fiber will be cut directly.The third type is the light decay caused by external force extrusion.Fiber optic cables are being laid. Straighten the optical cable from the optical cable shaft, and during the cable blowing process, if the bending radius of the cable is too small or hard objects such as stones cut the optical cable, the optical cable will be squeezed and deformed. It is easy to damage the fiber core and cause optical attenuation.The fourth is the light attenuation caused by the fiber material problem.Optical fiber production technology continues to improve, and early production of optical fiber cables, or low-quality optical cables often suffer from optical attenuation caused by the optical fiber material itself. In recent years, the quality of optical fiber materials and production processes has been continuously improved, and the light attenuation caused by the problems of optical fiber materials has been basically solved. In recent years, newly laid optical cables have fewer and fewer such faults due to optical attenuation caused by optical fiber materials, but on old optical cables, or optical cables with very poor quality, it is still occasionally found decline. When encountering such problems, under normal circumstances, the only solution is to replace the inferior optical cable.Fiber hope fiber optic cable and patch cord manufacturers can provide high-quality fiber optic cables, fiber pigtails, fiber patch cords, single-mode multi-mode fiber, welcome to inquiry!