What does DWDM use to combine multiple optical signals?
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DWDM (Dense Wavelength Division Multiplexing) is a technology used in optical fiber communication networks to transmit multiple signals over a single fiber. DWDM uses multiple wavelengths of light to carry multiple signals simultaneously, thereby increasing the capacity of the fiber optic cable.
To combine multiple optical signals, DWDM uses the principle of wavelength division multiplexing (WDM). In WDM, each signal is assigned a specific wavelength of light, which is then combined with other signals to form a composite signal. The composite signal contains multiple wavelengths, each carrying a separate signal.
DWDM uses a specific range of wavelengths called the C-band (conventional band) and L-band (long-wavelength band) to transmit signals. The C-band uses wavelengths between 1530 nm and 1565 nm, while the L-band uses wavelengths between 1565 nm and 1625 nm. Each wavelength is separated from the others by a specific frequency interval, which is referred to as the channel spacing.
To combine multiple optical signals, DWDM uses optical multiplexers and demultiplexers. An optical multiplexer combines multiple signals of different wavelengths into a single composite signal, while a demultiplexer separates the composite signal into its individual wavelengths, which can then be detected and decoded by the receiving equipment.
In summary, DWDM uses wavelengths of light to carry multiple signals over a single fiber optic cable. To combine multiple signals, DWDM uses optical multiplexers that combine signals of different wavelengths into a single composite signal.