CWDM (Coarse Wavelength Division Multiplexing) and DWDM (Dense Wavelength Division Multiplexing) are two wavelength division multiplexing technologies commonly used in fiber optic communication systems. They both allow the simultaneous transmission of multiple independent optical signals on a single fiber, thereby increasing fiber utilization and transmission capacity. However, there are some differences in wavelength range, channel spacing and application areas.
Coarse Wavelength Division Multiplexing:
Wavelength Range: CWDM uses a narrower range of wavelengths, usually between 1270nm and 1610nm. A typical CWDM system usually uses 8 wavelengths with 20nm spacing between each wavelength.
Channel spacing: CWDM systems have a relatively large channel spacing, usually 20 nm, which means that optical signals between different wavelengths are relatively easy to separate and identify when they are transmitted in an optical fiber.
Application areas: mainly used for shorter distance fiber optic communications, such as fiber optic transmission in data centers, enterprise networks or metropolitan area networks (MAN).
Dense Wavelength Division Multiplexing:
Wavelength Range: DWDM uses a wide range of wavelengths, typically between C-band (1525nm to 1565nm) or C+L-band (1525nm to 1610nm). A typical DWDM system can support tens or hundreds of wavelengths.
Channel Spacing: DWDM systems have relatively small channel spacing, typically 0.8nm or less. This means that optical signals between different wavelengths are transmitted more densely in the fiber, allowing for higher transmission capacity.
Application Areas: Mainly used for long distance fiber optic communications, such as fiber optic backbones, Wide Area Networks (WANs) or intercontinental fiber optic networks.
