Definition - What does Coarse Wavelength Division Multiplexing (CWDM) mean?
Coarse wavelength division multiplexing (CWDM), a variant of wavelength division multiplexing (WDM), is an optical transmission technique used for shorter distances as compared to dense WDM (DWDM).
CWDM transmits few channels and makes use of wider spacing in between the channels for distances of up to 60 km. CWDM's wider spacing of up to 20 nm, when compared with DWDM's 1.6 nm, can tolerate much higher temperature fluctuations.
In 2004, IEEE standardized CWDM for 10-Gb Ethernet.
Coarse wavelength division multiplexing (CWDM) is highly economical when compared to DWDM, as there is no need to stabilize the laser nor is there a need for an external modulator. By adjusting the drive current, the laser can be directly modulated. CWDM functions between 1265 and 1625 nm compared with DWDM's tighter range of 1530 to 1620 nm.
Although DWDM rules the long-haul network sector, CWDM is all set to help carriers take full advantage of their network capacity in the regional, metro and access network sectors. When compared to DWDM, CWDM supports fewer wavelengths; however, it is offered at a fraction of the cost of DWDM. This makes CWDM perfect for those areas having average traffic growth projections.
As many as 16 CWDM wavelengths over a single pair of fiber