Multiplexer (MUX) and demultiplexer (DEMUX) are two important components in the WDM network system. A MUX module combines multiple signals into a single input and forwards them to an output, while a DEMUX module splits an input signal into multiple forwarded output signals. The question is, whether a MUX can be used as a DEMUX?
In the use of passive wavelength division multiplexers, MUX module or DEMUX modules is used for multiplexing or demultiplexing. Since the transmission process of optical signals through optical devices is reversible, a single MUX module or DEMUX module can be used as either a multiplexing module or a demultiplexing module.
So, what is the difference between MUX module and DEMUX module?
The concept of link loss needs to be introduced here. WDM systems in commercial and industrial applications are more inclined to TFF technology due to its excellent reliability and stability. Different with free space technology, the WDM module using TFF technology needs to consider the link loss, that is, the pairing loss between a MUX and a DEMUX. In order to meet the requirements of lower channel loss and lower link loss, in actual production, we should pair the sequence of the same wavelength devices in the Mux module and Demux module, so as to meet the premise of lower single channel loss and achieve lower link loss.
Therefore, a MUX can be used alone as a DEMUX, but in point-to-point transmission applications, MUX needs to be paired with DEMUX to reduce the link loss of the entire link.
