By the time Optical Fiber reaches home, do you know why the signal is down?, the intensity of the light decreases.This means that as the light signal travels through the fiber, some of the energy of the light is lost.This means that something in the fiber, or for some reason, blocks the light signal from passing through.This is the transmission loss of the optical fiber.Only by reducing the fiber loss can the optical signal be unimpeded.
In order to measure the loss characteristics of an optical fiber, the concept of loss coefficient (or attenuation coefficient) is introduced here, that is, the number of decibels of optical power reduction caused by transmission unit length (1km) optical fiber. Loss coefficient is generally expressed as, and the unit is dB/km.
Optical fiber attenuation is an important factor that impedes the transmission of digital signals over long distances.The fiber loss directly affects the transmission distance or the distance between relay stations.
The main factors causing optical fiber attenuation are:
Intrinsic, bending, extrusion, impurity, uneven and butt etc.
Intrinsic: is the intrinsic loss of optical fiber, including Rayleigh scattering, intrinsic absorption, etc.
Bending: when the fiber is bent, the light in part of the fiber will be lost due to scattering, resulting in loss.
Extrusion: loss caused by slight bending of the fiber when it is squeezed.
Impurities: impurities in the optical fiber absorb and scatter light transmitted in the optical fiber, resulting in loss.
Inhomogeneity: loss due to inhomogeneity of refractive index of optical fiber materials.
Butt joint: loss caused by optical fiber butt joint, such as: non-coaxial (single-mode optical fiber coaxial degree requirements of less than 0.8 m), end face and axis is not vertical, end face is uneven, butt diameter mismatch and poor welding quality.
The additional losses are man-made during the laying of the optical fiber.In practical application, it is inevitable to connect the fiber one by one, and the fiber connection will produce loss.Tiny bending, squeezing and stretching forces also cause losses.These are losses caused by the service conditions of optical fiber.The main reason is that under these conditions, the transmission mode in the fiber core changes.Additional losses can be avoided.
In addition, there are ultraviolet absorption loss, infrared absorption loss, impurity absorption loss, atomic defect absorption loss and so on.