1, their own factors: the main cause of attenuation of the fiber itself: scattering, absorption, refractive index and other factors. These factors produce loss is the inherent loss of optical fiber.
2, human factors: in the construction of the project, due to the construction personnel construction standards are not high, the responsibility is not strong, resulting in fiber optic cable bending more than the limit, part of the optical fiber within the light will be caused by scattering and loss.
3, environmental factors: in the humidity of the environment for fiber optic splicing, too much water vapor in the air will affect the fusion splicer electrode discharge strength, which leads to uneven fusion of fiber optic joints, resulting in fiber optic joint loss.