Dense Wavelength-Division Multiplexing (DWDM) is a type of optical networking technology that enables the transmission of multiple signals over a single fiber optic cable. This technology is used to increase the capacity of a single fiber optic cable by multiplexing multiple signals into one fiber, allowing for more bandwidth and higher data rates than would be possible with a single wavelength. DWDM technology is used in long-haul fiber networks, such as those that connect cities, as well as in local access networks.
In DWDM, multiple signals are transmitted over a single fiber using different wavelengths of light. The spacing between the wavelengths is usually set at 200GHz or less, which corresponds to 1.6nm in wavelength units at 1550nm. This allows multiple signals to be transmitted simultaneously without interference. The three primary DWDM bands are the C-band, the S-band, and the L-band.
The C-band is a range of wavelengths between 1530 and 1565nm, while the S-band is a range of wavelengths between 1460 and 1530nm. Lastly, the L-band is a range of wavelengths between 1280 and 1360nm. Each of these bands is divided into multiple channels. In DWDM systems, each channel is assigned a specific frequency, which is used to separate the signals from each other.
DWDM technology is an essential part of any optical fiber network. It allows for more efficient use of the limited bandwidth available in a single fiber cable, increasing the capacity of the network by multiplexing multiple signals onto a single fiber. Additionally, DWDM technology allows for greater scalability, as it is easy to add more wavelengths to a network if more bandwidth is needed.