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Intramodal dispersion

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In fiber-optic communication, an intramodal dispersion, is a category of dispersion that occurs within a single mode optical fiber.[1] This dispersion mechanism is a result of material properties of optical fiber and applies to both single-mode and multi-mode fibers. Two distinct types of intramodal dispersion are: chromatic dispersion and polarization mode dispersion.

Chromatic dispersion

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In silica, the index of refraction is dependent upon wavelength. Therefore different wavelengths will travel down an optical fiber at different velocities. This implies that a pulse with a wider FWHM will spread more than a pulse with a narrower FWHM. This dispersion limits both the bandwidth and the distance over which the information can be transmitted. This is why for long communications links, it is desirable to use a laser with a very narrow linewidth. Distributed Feedback Lasers (DFB) are popular for communications because they have a single longitudinal mode with a very narrow line width.

See also

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References

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  1. ^ Senior, John M. (1992). Optical Fiber Communication Principles And Practice. Prentice Hall.