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.

CWDM highlights:

• As many as 16 CWDM wavelengths over a single pair of fiber
• CWDM channel spacing is 20 nm
• Distances as high as 120 km
• Scalable by hybrid CWDM/DWDM
• A highly cost-effective WDM solution
  

CWDM applications:

• Fiber exhaust relief
• In LAN and SAN connections
• Cost-effective WDM deployments in metro networks
• Main office to client-premise interconnection