• Wavelength Division Multiplexing allows two or more optical systems to operate over the same fibre



  • It uses light of different wavelengths or coloured laser light, thus effectively increasing the capacity of the fibre



  • The technique can be likened to Frequency Division Multiplexing in that separating optical wavelengths (colours) is little different from separating the frequencies of electrical signals



  • In order to work filters are used to pass the required wavelength, while blocking others



  • y using WDM it is possible to increased the capacity of a pair of fibres (one for transmit, one for receive) from 140Mbits/s to Gigabits or even Terabits/s