4-core optical fiber manufacturing: now fiber manufacturing methods are: inner tube CVD (chemical vapor deposition) method, the inner rod CVD method, PCVD (plasma chemical vapor deposition) method and the VAD (vapor axial deposition) method. 2. Fiber Attenuation: The main factors contributing to the fiber attenuation are: intrinsic, bending, compression, impurities, uneven and docking. Eigen: intrinsic loss of the fiber, including: Rayleigh scattering, intrinsic absorption. Bending: optical fiber bent portion of the fiber within the light is lost due to scattering loss caused. Extrusion: generating a slight bending caused by the squeezing of the fiber loss. Impurities: impurity absorption and light scattering within the optical fiber propagation in the fiber, losses. Uneven: the refractive index of the fiber material loss caused by uneven. Butt: fiber loss generated when docking, such as: different axes (single-mode fiber coaxial requirement is less than 0.8μm), face and the axis is not perpendicular, end injustice, heart butt diameter mismatch and poor weld quality. 4 core cable How to buy: Fiber optic cable indoor shopping tips restricted building environment, laying conditions, resulting in a structural design tends to complicate indoor cables, optical fiber and cable materials used to diversify, the mechanical properties and optical properties of the cable have focused on and so on. 1, by the use of the environment and locations can be divided into indoor trunk cable, indoor wiring cable and indoor trunk cable three. Interior trunk cable is provided within the main building, between the outer channel; and indoor wiring cable and indoor trunk cable is used to pass information to each specific location.