Wavelength-division multiplexing (WDM) is a technology used to increase the transmission capacity of an existing fibre optic network. It converts and transmits simultaneously many optical signals originating from different sources, of different power and different wavelength, within one optical fibre.

Passive solutions for the wave mutiplexing technique include: optical circulators, couplers, CWDM and DWDM multiplexers and demultiplexers and OADM filters. They are designed to be installed in telecommunication cabinets and are available in versions that enable installation e.g. in fibre optic chambers.  Their task is to increase the capacity of the network by enabling simultaneous transmission of up to several dozen signals without the need to expand the infrastructure.

The use of passive WDM solutions also improves the reliability and high security level of the network.  The configuration itself and the subsequent operation are simple and power-free. WDM saves costs and shortens the implementation time of the required systems.