CWDM is a technology that multiplexes optical fiber bandwidth by simultaneously transmitting multiple optical signals of different wavelengths through a single optical fiber. Compared to dense wavelength division multiplexing (DWDM), its wavelength spacing is coarser (typically 20nm), hence the. The focus of this paper is on the basics of designing and deploying Coarse Wavelength Division Multiplexing (CWDM) systems based on modular Wave-Division-Multiplexing (WDM) technologies and pre-connectorized (“plug-and-play”) solutions. Our CWDM products separate wavelength into bands of 20 nanometers to cover the complete fiber optical communication.