Dispersion in optical fiber is the phenomenon that the signals of different frequencies or different mode components in the fiber are scattered due to different transmission speeds. Dispersion affects the bandwidth of the fiber and limits the transmission capacity and distance of the fiber.
Because of the different signal frequencies and wavelengths, the difference in refractive index reflects the difference in their transmission speeds. Therefore, long-distance transmission, while the signals emitted cannot arrive at the same time, so that the change in signal waveform forms dispersion.
The emission modes are different at the same time, and the characteristic equation of the waveguide shows that the same wavelength wave has multiple incidence angle emission modes in the multimode fiber. Due to the different incidence angles, the light travels through the fiber differently, which results in a mixed signal waveform and dispersion at the end. There are other reasons for dispersion caused by the fiber material itself, such as gradient-type fiber refractive index does not meet the self-focusing characteristics of the signal dispersion.
