WDM is a technology that combines two or more optical carrier signals of different wavelengths (carrying various information) at the sending end through the Multiplexer, and couples them to the same optical fiber of the optical line for transmission; at the receiving end, through the Demultiplexer The optical carriers of various wavelengths are separated, and then further processed by the optical receiver to restore the original signal. This technology of simultaneously transmitting two or many optical signals of different wavelengths in the same optical fiber is called wavelength division multiplexing.

Introduction to DWDM

Before understanding DWDM, we start by understanding what WDM is. WDM (Wavelength-Division Multiple-plexing) is a wave splitter that can divide one (group) wavelength into many wavelengths. group of wavelengths) into seven-color light (seven wavelengths). In the earliest optical communication, an optical fiber was only designed to transmit light of a specific wavelength. Due to the development of WDM technology, an optical fiber can be changed from transmitting one signal to transmitting multiple A signal, under the same laying cost, increases the utilization rate of the optical fiber several times, so the concept of WDM was put forward shortly after the optical fiber was used for communication. But after WDM splitting, the energy allocated to each band is It is too small to be used for optical fiber signal transmission. It was not until 1994, after the Erbium-Doped Fiber Amplifier applicable to WDM was successfully commercialized, that the use of WDM was noticed by the industry. Due to the technical improvement of WDM, a WDM can A light source divides more and more channels, so for the sake of distinction, the one that can separate out fewer wavelengths is called Coarse WDM, and the one with higher wavelength density is called Dense WDM.