WDM (Wavelength Division Multiplexing ) is a transmission technology that uses one optical fiber to simultaneously transmit multiple optical carriers of different wavelengths. The transmission loss in optical fiber varies with the wavelength of light. In order to reduce loss as much as possible and ensure transmission effect, it is necessary to find the most suitable wavelength for transmission. After a long time of exploration and testing, light in the wavelength range of 1260nm~1625nm has the lowest signal distortion and loss caused by dispersion, and is most suitable for transmission in optical fiber.
The wavelength applications of optical fibers are divided into several bands, and each band is used as an independent channel to transmit an optical signal of a predetermined wavelength. ITU-T divides the frequency band of single-mode optical fiber more than 1260nm into several bands: O, E, S, C, L and U.
O Band
O band is the original band with wavelength range 1260-1360 nm. O band is the first wavelength band historically used for optical communication, with minimal signal distortion (due to dispersion).
E Band
E band is the extended band with wavelength range 1360-1460 nm. It is the least common of these wavebands. E band is mainly used as an extension of O band, but its use in optical communications is limited mainly because many existing optical cables show high attenuation in E band and the manufacturing process is very energy intensive. Read more on Wavebands in WDM.
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