CWDM (Coarse Wavelength Division Multiplexing) is used in situations where fiber cable capacity is limited or to increase bandwidth over a single fiber. It enables data transmission using different colors (wavelengths) over a single fiber strand; for instance, if a 1G link utilizes 10 wavelengths, it can transmit 1G data to 10 different destinations. CWDM systems are implemented using passive or active MUX/DEMUX devices and wavelength-specific SFPs. CWDM employs 18 wavelengths ranging from 1270 nm to 1610 nm, spaced at 20 nm intervals.
