Wavelength-division multiplexing equipment

Wavelength-division multiplexing (WDM) is a technology allowing simultaneous transmission of several informational channels through one optical fiber at different carrier frequencies.

WDM technology makes it possible to increase the channel carrying capacity using the already existing fiber-optic lines. Thanks to WDM it is possible to arrange a two-way multichannel transmission of traffic through one fiber (in common lines a pair of fibers is used to transmit in forward and backward directions).

The up-to-date WDM systems based on the standard frequency plan (ITU-T Rec. G.692) can be subdivided into three groups:

Coarse WDM (CWDM) – the systems with channels frequency separation of not less than 200 GHz, allowing multiplexing not more than 16 channels.
Dense WDM (DWDM) – the systems with channels separation of not less than 100 GHz, allowing multiplexing not more than 32 channels.
High Dense WDM (HDWDM) – the systems with channels separation of 50 GHz and less, allowing multiplexing not more than 64 channels.