The three prism will divide the white light into a seven color. If you send a white light pulse into the fiber, will there be seven color pulses? Because quartz fiber is not working in a visible light, we have not seen it, but it will have a similar phenomenon in infrared light.
If the optical wavelength of the optical signal propagating in the fiber is not very pure, that is, the optical signal contains several different wavelengths of light, then equivalent to the optical signal having several different wavelengths in the optical fiber. Medium spread. These different wavelengths of optical signals have been relatively delayed due to their communication speeds, and the result will have relative delay (or delays in the group). Usually, the dispersion D of the fiber is used to represent the group of the fiber, and the dispersion D represents the delay increment of each unit conveying distance. Specifically, it is a group caused by 1 km from 1 km from the nano-optical signal. Extension. The unit of material dispersion is PS / NM · km.
When the light propagates in the medium in the refractive index N, the relationship between the speed of speed V and the air in the air is:
V = C / N
The wavelength of light is different, the refractive index n is different, and the speed of light transmission is different. Therefore, when the light pulse emitted by a light source having a certain spectral width is transmitted into the optical fiber, the transmission speed of the light will change with the light wavelength, and the time delatability is generated when the terminal is reached, thereby causing a pulse wave shape.