CWDM and DWDM are both WDM technologies, which can couple different wavelengths of light into a single core fiber and transmit them together. DWDM (dense wavelength division multiplexing) technology is the most effective solution for line bandwidth expansion, but CWDM (coarse wavelength division multiplexing) technology has advantages over DWDM in terms of system cost and maintainability.
The latest ITU standard for CWDM is G.695, which specifies 18 wavelength channels spaced 20nm from 1271nm to 1611nm, taking into account the effect of water peaks in ordinary G.652 fiber, 16 channels are generally used. Because of the large channel spacing, the combined wave splitting devices and lasers are cheaper than DWDM devices.
DWDM channel spacing according to the need for 0.4nm, 0.8nm, 1.6nm and other different spacing, spacing smaller, need additional wavelength control devices, so the DWDM technology-based devices than the price of CWDM technology-based devices.
