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ITU grid

In Recommendations G.692 and G.694, the International Telecommunication Union( ITU-T) has specified wavelength ranges with the ITU-Grid that are particularly suitable for optical transmission. They are characterized by low attenuation and low dispersion.

The wavelengths and channel spacings specified by the ITU are defined for wavelength division multiplexing(WDM), coarse wavelength division multiplexing ( CWDM) and dense wavelength division multiplexing( DWDM). Depending on the wavelength division multiplexing, the wavelength spacing and the safety distances between the wavelengths differ.

The ITU-T standard G.694 deals with DWDM and CWDM. In G.694.1, the ITU grid, also known as the telecommunications window, is specified for DWDM. According to this, there is a safety margin of 0.8 nm between two wavelengths in DWDM. However, there are developments that work with half or even a quarter of the wavelength spacing, i.e. with 0.4 nm or even with 0.2 nm. The 0.8 nm spacing corresponds to a spacing of 100 GHz.

Optical transmission windows according to ITU, ITU-Grid

Optical transmission windows according to ITU, ITU-Grid

In ITU-T G.694.2 from 2002, CWDM is standardized with a wavelength spacing of 20 nm. The wavelength ranges are divided into a total of six wavelength bands, in which a total of 18 wavelengths are available for optical transmission. These are the O-band (Original) with five wavelengths between 1,260 nm and 1,360 nm, the E-band (Extended) with wavelengths between 1,360 nm and 1,460 nm, the S-band (Short Wavelength) with three wavelengths between 1,460 nm and 1.530 nm, the C-band (Conventional) with two wavelengths between 1,530 nm and 1,565 nm, theL-band (Long Wavelength) with three wavelengths between 1,565 nm and 1,625 nm, and the U-band (Ultralong Wavelength) between 1,625 nm and 1,675 nm.

Englisch: ITU grid
Updated at: 05.01.2018
#Words: 253
Links: indium (In), ITU telecommunications (ITU-T), transmission, attenuation (ATT), dispersion
Translations: DE

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