For sufficient and efficient use of enormous bandwidth resources brought by low-loss wave range of single mode fibers, an increasing number of telecommunication enterprises have turned their attention to the WDM technology. Basically, there are 2 alternatives for WDM: DWDM and CWDM. Lots of people feel confused about these two concepts. The differences between DWDM and CWDM are mainly reflected in the application scenes and costs.
In DWDM, the quantity of optical channel can reach up to 80 at line rates up to 10Gpbs, with the channel separation being as small as 0.8 or 0.4 nm, while CWDM, at the rates up to 10Gpbs and 40Gpbs, offers 15 optical channels that are spaced 20nm apart, which means the DWDM technology is preferable for high capacity environment(like Wide Area Network), whereas CWDM systems are much more fitted for Metropolitan Area Network. Furthermore, due to the narrower space among channels and higher capacity, DWDM system requires a more well-designed cooling system, more sophisticated and complicated laser resources and multiplexers, comparatively, CWDM system is much simpler, accounting for merely 40% of costs in DWDM.
