It is related to λ 4 is inversely proportional. When the wavelength is less than 0.8 micrometers, the Rayleigh scattering loss rapidly increases, limiting the use of optical fibers. The intrinsic absorption loss of SiO2 and doped oxide molecules in the fiber matrix material causes the attenuation of the fiber, which rapidly increases when the wavelength is greater than 1.7 micrometers. Therefore, the wavelength of this type of fiber is limited to the range of 0.8 to 1.7 micrometers.

In this range, the attenuation is mainly caused by impurities such as Fe++, Cu++and transition metal ions and OH - contained in quartz glass. Caused by absorption loss. With the improvement of purification process, the absorption loss of impurities has been basically eliminated, thus reaching the limit of Rayleigh scattering loss. The irregular small bending of optical fibers causes mode coupling, resulting in micro bending loss. Therefore, it is necessary to avoid micro bending of optical fibers in processing and use as much as possible.