A CWDM multiplexer combines a set of widely spaced wavelengths onto one fiber pair and separates them at the far end. The wide spacing is the whole economic trick: lasers do not need tight temperature control, optics stay inexpensive, and the system adds channels to existing fiber at a fraction of the cost of new construction. GRT manufactures CWDM equipment as part of its WDM range for exactly this duty — campus backbones, metro access rings and building interconnects that have outgrown a single pair.
Design with CWDM starts from the channel plan and the loss budget. Each mux/demux stage adds insertion loss; the channel optics at each end must be wavelength-matched to the plan; and the fiber’s water-peak characteristics matter on older plant at certain wavelengths. None of this is exotic, but it is why WDM is bought as a designed system — mux, channel optics and patch cords together — rather than as shelf parts. GRT quotes it that way.
Typical CWDM duties
- Campus backbone growth without new duct work
- Metro access: aggregating building links onto leased pairs
- Protocol mixing: Ethernet and storage on separate wavelengths
- Staged growth: light channels as demand arrives
CWDM or DWDM for a campus?
Usually CWDM: distances are short, channel counts moderate, and the economics favour uncooled optics. DWDM enters when channel counts or distances grow up.
Can CWDM channels carry 10G each?
Yes — channel rate is a property of the optics you plug in, and 10G per wavelength is a standard CWDM design point.