DWDM overview

Dense Wavelength-Division Multiplexing (DWDM) packs many channels onto one fibre with narrow spacing, mainly in the C-band (~1530–1565 nm). It is the technology behind long-haul and high-capacity metro links.

Dense and amplifiable

• Channels sit close together on the ITU grid (ITU-T G.694.1), typically 100 GHz or

50 GHz apart — see DWDM and the ITU grid.

• Because C-band channels fall inside the EDFA amplification window, dozens of

channels can be boosted together over long distances.

Cooled and often tunable

Narrow spacing demands wavelength precision, so DWDM lasers are temperature- stabilised (cooled). Many DWDM transceivers are tunable — one module can be set to any channel on the grid rather than being fixed to one colour.

Modules and CodingBox

DWDM optics come as DWDM SFP+, SFP28 and QSFP modules. For a tunable module, the channel (and thus wavelength) is set through the management interface — a capability CodingBox supports for tunable DWDM transceivers, alongside reading the current wavelength on the Check transceiver screen.