WDM & DWDM
Wavelength-division multiplexing (WDM)
is a method of network transmission along the fiber optic line to carry different wavelengths by a laser light. WDM can transmit data as 2.5 - 10 Gbps at 32 - 64 channels in the same time. Basically, WDM system uses "Multiplexer (mux)" to join the signals together before transmit out and a "De-multiplexer (demux)" at the receiver to split signals apart.
See the following picture for explanations.
Figure 1: mux and
demux flow
