Netnod has installed two Wavelength-Division Multiplexing (WDM) systems at the Interxion colocation centre as well as two of the Telecity colocation centres in Stockholm.

The WDM installation in these three colocation centres, allows Netnod to expand the capacity of the network without the need for more fibre connections, which in turn reduce the costs of operators connecting to Netnod from those locations. 

WDM is a technology that multiplexes multiple optical carrier signals on a single optical fibre by using different wavelengths (colours) of laser light to carry different signals. This allows for a multiplication in capacity, and enables bi-directional communications over one strand of fibre. It is a form of frequency division multiplexing (FDM), but is commonly called wavelength-division multiplexing. A WDM system uses a multiplexer at the receiver to join the signals together and a de-multiplexer at the transmitter to split them apart. With the right type of fibre, it is possible to have a device that does both simultaneously, and can function as an optical add-drop multiplexer. Dense wavelength-division multiplexing, or DWDM for short, refers to optical signals multiplexed within the 1550 nm band so as to leverage the capabilities and cost of erbium doped fibre amplifiers (EDFAs), which are effective for wavelengths between approximately 1525-1565 nm (C band), or 1570-1610 nm (L band).