CWDM modules-Coarse Wavelength Division Multiplexer
![](https://v4-upload.goalsites.com/57/editor_1513649539_CWDM.gif)
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 modules -Dense Wavelength Division Multiplexer
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
![](http://www.rfwireless-world.com/images/CWDM-vs-DWDM-spectrum.jpg)
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.
Specifications/Features | CWDM | DWDM |
---|---|---|
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 |
capacity | lower | higher |
cost | low | high |
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 |