Difference between CWDM and DWDM
CWDM-Coarse Wavelength Division Multiplexing
The figure-1 depicts CWDM based fiber system. As shown it is used to transmit 4 different applications using single optical finer instead of pair of fiber cables. Different applications are using different light wavelengths which helps in multiplexing and de-multiplexing applications at transmit and receive end.
DWDM-Dense Wavelength Division Multiplexing
The figure-2 depicts DWDM system consisting of transmitter and receiver parts. Typically DWDM consists of MUX, DEMUX, isolators, circulators, EDFA (Erbium Doped Fiber Amplifier) etc.
DWDM system basics
Figure-3 depicts spectrum of CWDM and DWDM technologies. As shown DWDM spectrum will have tighter wavelength spacing between the channels compare to CWDM counterpart. Following table compares the two.
|Full form||Coarse Wavelength Division Multiplexing,WDM system having less than 8 active wavelengths per optical fiber||Dense Wavelength Division Multiplexing, WDM system having more than 8 active wavelengths per optical fiber|
|characteristic||Defined by wavelengths||Defined by frequencies|
|Distance||short range communication||long range communication|
|Frequencies||uses wide range frequencies||uses narrow range frequencies|
|Wavelength spacing||more||less, hence can pack 40+ channels compare to CWDM in the same frequency range|
|Amplification||light signal is not amplified here||light signal amplification can be used here|
|Drift||Wavelength drift is possible||Precision lasers are needed to keep channels on the target|
|Spectrum utilization||Breaks the spectrum into big chunks||dices the spectrum into small pieces|
|No. of active wavelengths per fiber||Fewer than 8||More than 8|