Dense Wavelength Division Multiplexing (DWDM) is a wavelength division multiplexing (WDM) technology that expands the transmission capacity of existing optical fiber networks. It can multiplex multiple optical carrier signals onto a single optical fiber for transmission. Save a lot of fiber resources in distance transmission applications. There are two main types of current DWDM systems: passive DWDM systems and active DWDM systems.
Passive DWDM system
The passive DWDM system does not use active devices such as fiber amplifiers and dispersion compensators. The transmission distance of this system will be limited by the transmit power of the optical module, but it has the advantage of high channel capacity and is mainly used in metropolitan area networks and high Channel capacity in high-speed transmission lines.
Active DWDM system
Active DWDM is a system that includes a transponder. The role of the transponder is to perform optical-electrical-optical (OEO) conversion. In addition, the system is also equipped with multiple erbium-doped fiber amplifiers (EDFA) to ensure that the receiving end can receive high-quality optical signals, but the number of erbium-doped fiber amplifiers (EDFA) will be affected by fiber type, number of wavelength channels, Transmission rate, signal-to-noise ratio (OSNR) and other factors are limited.
The link length of the active DWDM system is not only related to the number of fiber amplifiers and the signal-to-noise ratio (OSNR), but also affected by the dispersion of the optical signal. Therefore, when designing an active DWDM system, the dispersion of the optical signal should be taken into consideration. If necessary, a dispersion compensator (DCM) can be added to the active DWDM system. It should be noted that the dispersion compensator (DCM) It will increase the insertion loss of the optical fiber link and affect the transmission distance of the active DWDM system.
